The labrisomids, or scaled blennies, are mostly small and inconspicuous fishes commonly found on and around Caribbean reefs. They comprise one of the largest families of New World reef fishes, with more than 50 regional species and many more cryptic species (distinct genetic lineages with subtle morphological differences) waiting to be described. Labrisomid genera tend to be speciose and species-level identifications are generally difficult. Fortunately, almost all the Atlantic labrisomids belong to just four genera. The larger and more conspicuous members belong to Labrisomus, presently with eleven Caribbean species (including two recently described species from Brazil but found widely in the Caribbean), and Malacoctenus, presently with eight Caribbean species. The two other genera, Starksia and Paraclinus, contain numerous species and are tiny and elusive, typically well-hidden and rarely encountered or photographed by divers. The remaining regional labrisomids are two obscure deep-water genera with a single species each: Nemaclinus atelestos, found on deep reef walls, and Haptoclinus apectolophus, an enigmatic species found only on the Arrowsmith Banks off the Yucatan at 1,000 feet deep.

Labrisomid larvae are very common in collections around Caribbean reefs and are present in more than 90% of my daily larval collections from Panama. They can be recognized by their long narrow body, large round eyes, and short pointed snout, with a long continuous dorsal fin with numerous slender spines, a long anal fin with just two slender spines, a very short and narrow caudal peduncle, pelvic fins thoracic (in front of the pectoral fins) with only 2 or 3 long strand-like rays (not markedly curled-up over the body), no obvious head spines, no silvery peritoneal lining, and light markings. The markings vary little within the family and typically comprise a row of melanophores along the anal-fin base (sometimes also the dorsal-fin base) and a pattern of spots on top of the head.

These larval characters are shared with the larvae of the closely-related hole-dwelling blennies of the family Chaenopsidae, which are similar in appearance to larval labrisomids but much less frequent in larval collections. The chaenopsid blennies are distinguished mainly by having more dorsal-fin elements (although there is a small overlap): most chaenopsids have more than 31 dorsal-fin elements, often with 13 or more soft rays, while regional labrisomids have 12 or fewer dorsal-fin soft rays (with a rare 13) and rarely have more than 32 total dorsal-fin elements. The Caribbean chaenopsids that can overlap the low dorsal-fin counts of labrisomids are Coralliozetus cardonae and the Emblemariopsis species, along with the rare Emblemaria vitta. The larvae of these chaenopsids can be distinguished from similar labrisomid larvae by their smaller size at stage, fewer markings, and their mostly differing modes and combinations of fin-ray counts, as well as fewer procurrent caudal-fin rays. The taxonomic features generally separating the two families, i.e. scales on labrisomids and scales absent on chaenopsids and a set of osteological characters, are useless for larval stages.

The unusual genus Stathmonotus is still considered chaenopsid even though their dorsal fin is made up of all spines and they can have scales. Some labrisomids of Paraclinus also have a dorsal fin made up of all spines; fortunately the larvae of the two genera are easily distinguished by morphology.

Labrisomid larvae generally resemble those of the other blennioid families of reef fishes- they can be distinguished easily from larvae of the combtooth blennies (family Blenniidae), which have fewer dorsal-fin spines than soft rays and blunt snouts at all stages (labrisomids have twice as many dorsal-fin spines as rays (or more) and pointed snouts as larvae). Larvae of the blennioid triplefins (family Tripterygiidae) have three separate dorsal fins and distinctive markings and the stargazers (family Dactyloscopidae) have relatively foreshortened anterior bodies and curled-up pelvic fins.

Larval labrisomids are superficially similar to the larvae of gobies and scarids, which also often have a similar anal-fin row of melanophores and are very common in collections and are about the same size as labrisomid larvae. However, those larvae notably have many fewer dorsal-fin spines, short and/or fused pelvic fins, and narrowed or oddly-shaped eyes, while later-stage labrisomids have long thread-like pelvic fins and large round eyes. Larval gerreids (mojarras) are also common and can be mistaken for labrisomid larvae, however they have silvery abdominal linings. Larval grunts (Haemulidae) often have an anal-fin row of melanophores and can resemble earlier-stage labrisomids, but they develop a notably short anal fin and characteristic tail spots.

Labrisomid larvae share, to varying degrees, a basic set of melanophores that develop progressively after hatching and are very useful for identifying larvae at least to genus and often to species. The timing of the development of each marking can be somewhat variable within a species, resulting in a variety of patterns on earlier-stage larvae that preclude a simple key to species identification. Late and pre-transitional larvae typically have their full complement of larval melanophores, making identifications at these larger sizes somewhat easier. During transition, however, larval melanophores begin to disappear and metamorphic melanophore patterns develop. Metamorphic melanophores consist primarily of intricate patterns of small surface melanophores, usually starting on the head and spreading over the body to form the juvenile markings. This transitional sequence is also variably timed, promoting a proliferation of intermediate melanophore complements that can easily lead to the impression of a greater number of species than are actually present.

The basic melanophore complement on most labrisomid larvae comprise the following list, from head to tail:

note: a number of other melanophores are present at specific, and often diagnostic, locations on the larvae of particular species (or groups of species) and are discussed under the genus or species descriptions in the next sections.

Anal-fin Base Row: A row of melanophores along the posterior ventral midline is present on all labrisomid larvae, typically one at the base of each anal-fin soft ray and sometimes at the base of the spines as well. On earlier-stage larvae, only some of the anal-fin rays have an associated melanophore and the sequence of development of the row can be a useful character. Some melanophores in the anal row can be irregular, either larger or deeper (often both), and then are an important diagnostic character. .(anal row melanophores). (left; Starksia occidentalis with larger deeper last one)

The total posterior ventral-midline melanophore count is a useful screening tool for larvae, counting both anal row and ventral caudal peduncle melanophores. pvm

Labrisomids have demersal brooded eggs and hatch several days after fertilization as well-developed larvae around 3 mm in length. The early-stage post-flexion larvae can be recognized by a long, narrow, tapering body with a small pointed head, medium terminal mouth, relatively large, mostly rounded eye, a few small preopercular spines (or none), snout-to-vent length slightly less than half of body length, a short caudal peduncle with long dorsal and anal-fin bases with early-forming posterior elements on the dorsal fin and inconspicuous slender spines and rays. Pigmentation follows the genus-level identification patterns, primarily various head and ventral midline melanophores. Before larvae develop their full complement of fin rays and melanophore patterns, species-level identifications would often require DNA sequencing. The pigment pattern on the common Malacoctenus macropus larvae comprises a deep nuchal melanophore, usually one or two midbrain cranial melanophores, a cheek melanophore, and the anal row extending onto the ventral midline of the caudal peduncle. There are internal otic and retroperitoneal melanophores.

In addition to the basic set of labrisomid melanophores discussed above, some species, or sets of species, have distinctive patterns of larval melanophores that are indispensable for identifications. A very few melanophore locations are unique to larvae of one species, but combinations are often diagnostic for species. An interesting observation is that melanophores that are characteristic of one species may occasionally (or rarely) be found on other related species to a lesser degree or at a later point in transition. Because of these overlaps, not every larva can be easily assigned to species on the basis of a diagnostic larval melanophore pattern; several characters sometimes need to be weighed in the decision (note that metamorphic melanophore patterns are very specific and diagnostic). No single marking identifies all Malacoctenus or Labrisomus, but some are found only in one genus (but not in all of the species), such as the pair of melanophores behind the tip of the upper jaw on some Labrisomus.

The mouth is typically small in both juvenile and adult Malacoctenus (and L. nigricinctus) and the maxilla extends back only to the level of the anterior orbit vs. large and extending back past the level of the pupil in most Labrisomus. This mouth-size character is the best character for distinguishing juveniles but does not generally apply in larvae, and, when it does, can be quite subtle, although sometimes useful. For example, in the photograph below, the maxilla is distinctly longer in the 15 mm Labrisomus guppyi larva on the left vs. the same-sized Malacoctenus triangulatus on the right (note eye diameters are identical).

The dorsal-fin profile typically differs between genera (and often species). A loose but useful rule for juveniles and adults is that most Malacoctenus have very short penultimate and third-to-last dorsal-fin spines, less than a third the length the longest dorsal-fin soft ray, while many Labrisomus have the shortest dorsal-fin spine about half or more the length of the longest dorsal-fin soft ray. There are certainly exceptions: L. nigricinctus, L. albigenys, and, to a degree, the 19-spined Labrisomus species have short posterior dorsal-fin spines, and M. macropus and M. boehlkei have relatively long posterior spines. The dorsal-fin profiles of larvae do not always match those of juveniles or adults, but they can be helpful, especially for late larvae approaching transition. In general, most Labrisomus larvae have relatively low soft dorsal fins while many Malacoctenus larvae have high soft dorsal fins and short posterior dorsal-fin spines (see transitional larvae below: Labrisomus haitiensis top vs. Malacoctenus versicolor bottom).

Counts are mostly from Springer's classic monograph:

Springer, V. G.: Systematics and zoogeography of the clinid fishes of the subtribe Labrisomini Hubbs. Pubs. Inst. Mar. Sci. Univ. Texas 5:417–492 (1959), often cited as (1958).

note: Some Starksia species can barely overlap the lower range of fin-ray counts for those few Malacoctenus species that can have 8 or 9 dorsal-fin soft rays and 14 or fewer pectoral-fin rays.

Diagnosis: The modal fin-ray count of D-XVIII,12 A-II,18 and P-14 indicates Malacoctenus versicolor and several Labrisomus species, including L. nuchipinnis, L. conditus, and L. cricota. M. versicolor can be distinguished from the latter species by the dorsal-fin profile, with the first spine always the longest (vs. shorter than the others in L. nuchipinnis and L. conditus) and the third-to-last dorsal-fin spine short (three times into the longest soft ray) vs. half or more in the three Labrisomus, as well as a smaller mouth (maxilla not past the midpoint of the eye). The 19-spined Labrisomus species can sometimes overlap the fin-ray count, but they also have distinctly larger mouths (maxilla past the midpoint of the eye). The fin-ray count also (barely) overlaps with the chaenopsid blenny Coralliozetus cardonae, which are much smaller at all stages and have only 3-4 procurrent caudal fin rays (vs. 6-8). (DNA)

Ecology:
The barfin blenny is a small blenny found in shallow coral and rocky areas and mixed habitats with complex structure and uncommonly observed or photographed by divers. Indeed, photographs on the web and in guidebooks are often the barred phase of M. macropus, including those in Humann's book and on the Smithsonian larval-fish website. Genuine barfin blenny photographs include those from St. Vincent by Keri Wilk (ReefNet) and from Eleuthera, Bahamas by Louis Johnson. The species is found mainly in Florida, the Bahamas, and the northern Caribbean islands; it is not recorded from the Gulf of Mexico or Bermuda and appears to be replaced by M. delalandii to the south of Belize and the lower Antilles, i.e. in Panama to Venezuela and mainland Brazil. Barfin blennies are infrequent in collections and are found in numbers only in rare localities, especially in the Bahamas. Their larvae are rare in collections.

Description:
Pre-transitional larvae: Body long, moderately narrow, and thin with a medium round eye, pointed snout, and small terminal mouth. Long continuous dorsal and anal fins with a very short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. On the head there are several large melanophores along with several smaller melanophores, overlying all quadrants of the fore- and midbrain, usually more than 5 per side. There is a cheek melanophore on each side. There are no melanophores along the base of the dorsal fin, but there are several melanophores at the base of the upper and lower caudal-fin segmented rays. Along the ventral midline there is a melanophore at the isthmus and deep at the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, closely followed by two or three along the ventral midline of the caudal peduncle. Internal melanophores comprise only the basic complement: the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: M. versicolor larvae in transition develop lines and well-outlined patches of small surface melanophores over the head, notably with two thin lines extending down and slanted forward from the orbital rim at 6 o'clock. The metamorphic melanophores on the body form complex shapes and rings, some of which connect into narrow bars that extend uninterrupted over the dorsal fin to the edges of the membranes. Multiple long cirri form on the nape, over the eye, and over the nasal tube.

Juveniles: M. versicolor juveniles have relatively narrow dark bars on the body that extend across the dorsal-fin membranes, notably not widening as they reach the edge of the fin. The bar under the last dorsal-fin spine is characteristically narrow and unbranched. The first three dorsal-fin spines are distinctly longer than all subsequent spines.

Analogues:
Several other Malacoctenus species can have larvae with the head speckled with 10 or more spots. M. triangulatus larvae usually have many more. The two species are similar in size and morphology, but can be separated by fin-ray counts: 18 dorsal-fin spines and 18-19 anal-fin soft rays in M. versicolor vs. 20 dorsal-fin spines and 20-21 anal-fin soft rays in M. triangulatus. In addition, M. versicolor larvae have an obvious third pelvic-fin ray about two-thirds the length of the second vs. less than half the second and often inconspicuous in M. triangulatus and a row of melanophores along the caudal-fin base vs. none or a single melanophore (at the base of the largest dorsal procurrent ray) in typical M. triangulatus larvae. M. gilli larvae can occasionally have similar numbers of head spots, but most have 20 dorsal-fin spines and they are smaller and lightly marked, with no melanophores along the caudal-fin base. M. boehlkei larvae also have numerous head spots, but have 33 dorsal-fin elements.

Since the markings and size of M. versicolor larvae can be intermediate between typical Malacoctenus and Labrisomus, separation from Labrisomus larvae can be problematic. Several of the Labrisomus species that share fin-ray counts with M. versicolor are slimmer forms with smaller mouths that can share morphology with Malacoctenus: i.e. L. nuchipinnis, L. conditus, L. cricota, as well as the two small species, L. nigricinctus and L. albigenys; the latter two with fewer head melanophores and much shorter first dorsal-fin spines than M. versicolor. Larvae of L. nuchipinnis, L. conditus, and L. cricota differ primarily in having melanophores along the bases of the spinous and soft dorsal fins and a prominent U, V, or O-shape arrangement of large melanophores over the head. The 19-spined Labrisomus species can sometimes overlap the 18 dorsal-fin spine count, but they typically have melanophores along the dorsal-fin base and behind the tip of the upper jaw, as well as a different dorsal-fin profile as larvae, with shorter first spines and relatively longer posterior spines. L. haitiensis larvae share all of these differences (except the shorter first dorsal-fin spine) and also have higher fin-ray counts.

Transitional M. versicolor larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, especially the narrow bars on the body vs. wide inverted triangles in transitional M. triangulatus and generally wider bars or triangles, covering four or more dorsal-fin-spine bases, in the other barred Malacoctenus species. Some transitional M. macropus have a pattern of of ovals, but not organizing into long bars. Most transitional Labrisomus larvae have uniform metamorphic melanophore patterns without the sharply-outlined shapes of M. versicolor. The exception is L. haitiensis, whose larvae develop a similar pattern of well-delineated shapes, however their shapes do not connect and form long narrow bars (and they have higher fin-ray counts, a short third pelvic-fin ray, and a larger mouth).

Juvenile M. versicolor are distinguished by their prominent narrow dark bars on the body which extend onto the dorsal fin membranes, but several other related species can share this character. An uncommon barred variant of juvenile M. macropus has the bars, but are distinguished by having long single cirri over the nape, eye, and nasal tube (vs. multiple in all congeners) and the bars under the last spines and first rays merge to form a Y or V-shape and the bars are often limited to the dorsal aspect. M. delalandii can appear very similar, sharing the bar pattern extending onto the dorsal fin, but their dark bars distinctly widen, meeting (or almost meeting) at the edges of the fin. They also have relatively shorter first dorsal-fin spines (the mid-fin spines are longer than the first) and one or two more dorsal-fin spines. Among the Labrisomus, L. cricota is the most similar to M. versicolor, with similar markings and also with a long first dorsal-fin spine, but the mouth is larger (maxilla past the midpoint of the eye), the second bar on the dorsal fin slants down and forward to the operculum, and the last bar on the spinous segment of the dorsal fin covers only spines (vs. the base of rays as well). L. conditus and L. nuchipinnis have short first dorsal-fin spines and the aforementioned bar differences. L. nigricinctus juveniles have prominent bars, but have an obvious large opercular ocellus. Other Labrisomus species can have similar narrow bars on the body extending onto the fins, but are separated by their blunt snouts and large mouths.

Diagnosis: The modal fin-ray count of D-XX,10 A-II,19 and P-14 indicates Malacoctenus delalandii or M. gilli. Many M. aurolineatus share this fin-ray count, but their mode is 11 soft dorsal-fin rays. Some M. erdmani share the median-fin ray count but have a mode of 16 pectoral-fin rays. L. kalisherae, L. bucciferus, and L. haitiensis can also overlap the fin-ray count. The species is often spelled as Malacoctenus delalandei. (DNA)

Ecology:
The Brazilian blenny is found mostly in the southern Caribbean, where it seems to replace M. versicolor. The species has been collected from the inshore reefs of Belize south along the Central American coastline and across to NE Venezuela, where it is the most abundant species of the genus. Their range extends south to mainland Brazil, but not to the offshore islands of Noronha and Rocas. They are small blennies found on inshore shallow reef areas with complex structure; within most of their Caribbean range they are not commonly observed by divers. Their larvae are unknown or unrecognized in collections.

Description: (larvae unknown)

Juveniles: M. delalandii juveniles have dark bars on the body that extend uninterrupted over the full-width of the dorsal fin. The dark bars on the fin membranes distinctively expand outwards, often meeting at the fin edge. There is a dark spot on the lower operculum, often outlined and elongated, but not an obvious round ocellus.

Analogues:
Juveniles of M. versicolor can appear quite similar, but their first dorsal-fin spine is notably longer than the rest (vs. M. delalandii with the first spine about equal or shorter than the mid-fin spines), the bars that extend onto the fins do not expand to meet at the edges, the bar under the last dorsal-fin spines is narrow and separate from the next dark patch forward (vs. widening anteriorly as it spreads onto the fin in M. delalandii), and the dorsal-fin spine count is lower. An uncommon barred variant of juvenile M. macropus can also have bars on the body extending uninterrupted over the dorsal fin, but they also do not expand to meet at the edges, their fin-ray counts are different, and they have long single cirri (vs. multiple in M. delalandii and M. versicolor). Labrisomus nigricinctus can share the barred pattern, but they have an obvious round opercular ocellus.

Diagnosis: The modal fin-ray count of D-XX,10 A-II,19 and P-14 indicates Malacoctenus gilli and M. delalandii. Some M. aurolineatus can share this fin-ray count, but most have 11 soft dorsal-fin rays. Some M. erdmani share the median-fin ray count but have a mode of 16 pectoral-fin rays. L. kalisherae, L. bucciferus, and L. haitiensis can also overlap the fin-ray count. (DNA)

Ecology:
The dusky blenny is a somewhat common small blenny found primarily in shallow mixed habitats in bays. They have a curious, mostly island, distribution, found in the east from Bahamas and the Antilles down to offshore Venezuela and then in the west in Yucatan, Belize, and some offshore islands, but apparently not in Florida, Panama and the SW Caribbean or NE Venezuela. Their larvae are occasional in collections.

Description:
Pre-transitional larvae: Body long, narrow, and thin with a large round eye, pointed snout, and relatively small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. The complement of melanophores on the top of the head is quite variable, with one to several larger melanophores overlying the midbrain lobes and sometimes additional smaller melanophores over the forebrain lobes (may be pseudo-larval: developing during transition, but look like larval melanophores). There is a cheek melanophore on each side. There are no melanophores along the base of the dorsal or caudal fins. Along the ventral midline there is notably no isthmus melanophore, but there is a deep melanophore behind the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray (often not the last), followed by one or two melanophores along the ventral midline of the caudal peduncle. Internal melanophores comprise only the basic complement: the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: M. gilli larvae in transition first develop patches of small surface melanophores over the head, including a long bar down from the orbital rim at 5 o'clock and a broad eye-stripe from the orbital rim to the mid-maxilla. There are often several small pseudo-larval melanophores over the cranium in addition to the fine surface array. The fine melanophores on the pectoral-fin-base develop first as two small patches along the lower margin of the fleshy pectoral-fin base. Fine metamorphic melanophores later extend onto the body, forming complex patches and often arrays of small dark spots and a large dark spot forms on the first two dorsal-fin spine membranes. Multiple long cirri form on the nape, over the eye, and over the nasal tube.

Juveniles: M. gilli juveniles have very distinctive markings, including a large black spot over the first two dorsal-fin spine membranes and an ocellated spot with a blue center over the rear spinous dorsal fin which extends well onto the body.

Analogues:
The variable occurrence of one to several large spots over the rear cranium and/or additional smaller spots forward overlaps the head pattern found on most other congeners. Reduced-complement M. gilli are the only Malacoctenus larvae that share the bare-forebrain-lobes pattern characteristic of M. macropus and M. erdmani. Fortunately, the anterior ventral midline series differs: M. gilli larvae have a deep pelvic-fin base melanophore but no isthmus melanophore while the remaining Malacoctenus have both (most species) or neither (M. macropus and M. erdmani). M. versicolor and M. triangulatus usually have more numerous head melanophores, often 10+ per side. M. versicolor and M. aurolineatus larvae also differ by having melanophores along the caudal-fin base. The D-XX,10 combination occurs in about two-thirds of M. gilli individuals, but is uncommon among congeners other than M. delalandii. M. boehlkei larvae have multiple head spots in alll quadrants, but have 33 dorsal-fin elements.

Early transitional M. gilli larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. the combination of the 5 o'clock bar of melanophores, an eye stripe to the mid-maxilla, and two patches of melanophores along the lower edge of the pectoral-fin base. M. triangulatus have a quite similar marking pattern at transition, but have a single central patch along the lower rim of the pectoral-fin base; M. macropus are also similar but have a stripe across the lower pectoral-fin base (and single cirri).

Once recruits develop the large dark spot at the front of the dorsal fin and the characteristic ocellus on and below the rear spinous dorsal fin, they are easily distinguished from all other labrisomids.

Diagnosis: The modal fin-ray count of D-XX,11 A-II,19-20 and P-14 indicates Malacoctenus aurolineatus and Labrisomus haitiensis. This fin-ray count falls within the range for many other species in the group: M. versicolor, M. delalandii, M. gilli, and M. triangulatus, as well as L. kalisherae and L. bucciferus. (DNA)

Ecology:
The goldline blenny is a common small blenny found primarily in exposed shallow eroded limestone habitats and mixed coral substrates. They can be found in Florida, the Bahamas, at the mouth of the Gulf of Mexico and all of the Caribbean Sea, except NE Venezuela. Their larvae are occasional in collections.

Description:
Pre-transitional larvae: Body long, moderately narrow, and thin with a large round eye, pointed snout, and small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. On the head there is a large midline melanophore overlying the midbrain lobes and usually another single large midline melanophore over the forebrain lobes; less often, the anterior melanophores can be smaller, off-center, or paired. Occasionally there are one or a few additional small associated melanophores, although the total number of larval melanophores on top of the head rarely exceeds 5. There is a cheek melanophore on each side. Along the dorsal fin there is a melanophore at the base of some or all of the soft rays (occasionally also at the base of one or two of the last dorsal-fin spines). There are small melanophores in a thin line along the base of the caudal-fin rays, often both procurrent and segmented. Along the ventral midline there are melanophores at the anterior isthmus as well as at the mid-isthmus at the cleithral symphysis, in addition to deep just behind the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray (often not the last), closely followed by a series (up to 4) along the ventral midline of the caudal peduncle up to the procurrent caudal-fin rays. A row of internal melanophores overlies the vertebral column, spaced every 2-4 vertebrae, extending to the caudal peduncle, where the melanophores can overlie each vertebral body (often inconspicuous in stout-bodied larvae). Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: M. aurolineatus larvae in transition develop patches of small surface melanophores over the head, including a short bar slanting forward and down from the orbital rim at 6 o'clock (and no obvious eye-stripe from the orbital rim to the mid-maxilla). In addition, a distinctive long, thin, and straight vertical bar forms on the pectoral-fin base. Fine metamorphic melanophores later extend onto the body, forming complex patches resembling inverted triangles. Multiple long cirri form on the nape, over the eye, and over the nasal tube.

Juveniles: M. aurolineatus juveniles have an H-pattern of two broad connecting dark bars on the anterior body and a lighter rear body. They notably have no large dark spot at the front of the dorsal fin, on the operculum, or on other fins. Two prominent long dark vertical lines on the pectoral-fin base are diagnostic in well-marked individuals.

Analogues:
M. aurolineatus larvae can be distinguished from other labrisomid larvae by having fewer than 5 melanophores on the top of the head combined with melanophores along the soft dorsal-fin base and caudal-fin base. The other Malacoctenus species with fewer than five melanophores on top of the head, M. macropus, M. erdmani, and sometimes M. gilli, have no melanophores along the dorsal or caudal-fin bases. The most common configuration of two large midline melanophores spaced well apart on top of the head and two midline melanophores along the isthmus is not shared by other labrisomid larvae. Some Labrisomus larvae also have melanophores along the soft dorsal-fin base, but they always have more speckled heads than M. aurolineatus. L. albigenys and L. nigricinctus larvae also have few head melanophores as well as isthmus and pelvic-fin base melanophores and are similar in size and shape, but the former have a distinctive enlarged anal-fin base melanophore, a side-by-side pair of melanophores over the rear cranium, and no caudal peduncle ventral midline spots, and both have no caudal-fin base or soft dorsal-fin base melanophores (and usually lower fin-ray counts).

Early transitional M. aurolineatus larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. the combination of the 6 o'clock bar slanting forward, the absence of an eye stripe to the mid-maxilla, and, most distinctive, a long, narrow, and straight vertical line on the pectoral-fin base that is not shared by other transitional labrisomid larvae.

Juveniles later develop a second and separate long vertical line on the pectoral-fin base (similar lines in M. gilli are linked with a crossbar in an H-pattern or form a Y in M. triangulatus), broad inverted-triangle bars connected in an H-shape on the anterior body, and, notably, the absence of large spots or ocelli on the fins.

Diagnosis: The modal fin-ray count of D-XX,12 A-II,20-21 and P-14-15 indicates Malacoctenus triangulatus and falls within the range for M. aurolineatus, L. bucciferus, and L. haitiensis. (DNA)

Ecology:
The saddled blenny is the most commonly observed labrisomid on coral reefs in the region (M. macropus are generally more common but they are less conspicuous and less associated with coral habitats). Saddled blennies have one of the widest of distributions for regional reef fishes; they are found in Bermuda, Florida, the Gulf of Mexico, the Bahamas, all of the Caribbean Sea including NE Venezuela, as well as in Brazil and on many of its offshore islands. Their larvae are common in collections.

Description:
Pre-transitional larvae: Body long, moderately narrow, and thin with a large round eye, pointed snout, and small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. The full complement of melanophores on the top of the head comprises a scattering of large spots grading down to small, even tiny, spots (typically 10 or more per side, often many more), sometimes with the large spots arranged in two inward-facing crescents in a U- or O-shape. Occasional larvae have incomplete complements, sometimes just one or two large melanophores with one or a few smallerl spots. There is a cheek melanophore on each side. Typical lightly-marked larvae have no melanophores along the dorsal-fin base. Many lightly-marked larvae do have a characteristic single melanophore near the base of the largest dorsal procurrent caudal-fin ray, but no additional caudal-fin base melanophores. (A "dorsal-row" variant with melanophores at the base of some or all of the soft dorsal-fin rays and even along the base of some dorsal-fin spines occurs among some early transitional larvae. These larvae can also have melanophores along the base of the caudal-fin rays. It is unclear whether these larvae represent a regional variant in the Antilles or are only a variation during early transition and appear the same as lightly-marked larvae at earlier stages.) Along the ventral midline there is a melanophore at the mid-isthmus (rarely an additional one on the anterior isthmus) and one deep behind the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray (sometimes not the last), followed in some larvae by one to three spots along the ventral midline of the caudal peduncle (many lightly marked larvae have none). A row of internal melanophores overlies the vertebral column, one per vertebra, along the mid- and rear body, not continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: M. triangulatus larvae in transition develop patches of small surface melanophores over the head, including a short bar down from the orbital rim at 5:30 o'clock and a broad eye-stripe from the orbital rim to the mid-maxilla. In addition, the melanophores along the lower edge of the fleshy pectoral-fin base form a single patch midway from the body to the fin-ray insertion, which later develops into a Y-shaped bar. Fine metamorphic melanophores extend onto the body forming complex patches, mostly on the upper body, roughly in the shape of wide inverted triangles. Multiple long cirri form on the nape, over the eye, and over the nasal tube.

Juveniles: M. triangulatus juveniles develop a large dark spot at the base of the second and third dorsal-fin spines that extends onto the body, followed by a row of five wide inverted triangles extending to the tail.

Analogues:
In general, M. triangulatus larvae can be distinguished from most other Malacoctenus larvae by having more than 10 melanophores per side on the top of the head, a pattern shared only by some larvae of M. versicolor. The two species are also very similar in size and morphology, but fortunately can be reliably separated by fin-ray counts: 18 dorsal-fin spines and 18-19 anal-fin soft rays in M. versicolor vs. 20 dorsal-fin spines and 20-21 anal-fin soft rays in M. triangulatus. In addition, M. versicolor larvae have an obvious third pelvic-fin ray about two-thirds the length of the second vs. less than half the second and often inconspicuous in M. triangulatus and a row of melanophores along the caudal-fin base vs. at most a single melanophore (at the base of the largest dorsal procurrent ray) in M. triangulatus larvae (with rare exceptions). Larval M. boehlkei also have a short third pelvic-fin ray, a feature shared only by M. triangulatus and L. haitiensis, and can have multiple spots over each quadrant of the cranium; they are best distinguished from M. triangulatus by having relatively long posterior dorsal-fin spines and usually more fin rays (a rare specimen of M. triangulatus could have the same count).

Since the markings, morphology, and size of M. triangulatus larvae can be intermediate between typical Malacoctenus and Labrisomus, separation from Labrisomus larvae can be problematic. This is especially true for those variants with melanophores along the dorsal and caudal-fin bases and/or a reduced complement of head melanophores, thus resembling the pattern for many Labrisomus larvae. The fin-ray count is helpful, with most M. triangulatus having a high fin-ray count of D-XX,12 and A-II,21, fortunately non-overlapping with several of the slimmer Labrisomus that can share morphology with Malacoctenus (L. nuchipinnis, L. conditus, L. cricota, as well as the two small species, L. nigricinctus and L. albigenys; the latter two with many fewer head melanophores than M. triangulatus). The most similar Labrisomus larva is L. haitiensis, which can share both the high fin-ray counts and the inconspicuous short third pelvic-fin ray and its head melanophore pattern of a U-shape of six large spots can overlap with reduced-complement M. triangulatus larvae (and the occasional L. haitiensis larva have a few additional small spots). L. haitiensis larvae, however, always have the row of melanophores along the dorsal-fin base and a pair of prominent melanophores near the tip of the upper jaw (the former rare in M. triangulatus) and have a different dorsal-fin outline, with longer posterior spines. Some of the remaining 19 and 20-spined Labrisomus species can overlap in fin-ray counts with M. triangulatus, but those larvae have an obvious third pelvic-fin ray which is inconspicuous in M. triangulatus and often uniformly sized head melanophores (vs. graded tiny to large).

Transitional M. triangulatus larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. the combination of the 5:30 o'clock bar, an eye stripe to the mid-maxilla, and a single patch of melanophores (later developing into a Y-shape) along the lower edge of the pectoral-fin base. They can be separated from transitional Labrisomus by the metamorphic melanophore pattern as well as the dorsal-fin outline (third-to-last spine less than a third the length of the longest soft rays vs. often half or more) and long cirri (about a pupil width or more vs. short, esp. orbital).

Once they develop a large dark spot at the front of the spinous dorsal fin, juveniles can be separated by that feature from most other Malacoctenus species except M. gilli, which share the spot but also have a distinctive ocellus at the rear spinous dorsal fin, and M. boehlkei, which have the dorsal-fin spot ocellated (with yellow) and elevated some distance above the base of the fin. The inverted-triangle pattern for which the species is named is not diagnostic in juveniles- the basic pattern is shared by several congeners. Juvenile L. nuchipinnis, L. conditus, and L. cricota have a similar dorsal-fin spot and some may be missing their opercular ocellus or dark spot; in that case the dorsal-fin outline (with medium-length posterior spines), a longer third pelvic-fin ray, and reticulated markings on the body should distinguish them from M. triangulatus. Later they diverge markedly in morphology becoming bulkier with a large mouth and smaller eyes.

Diagnosis: The modal fin-ray count of D-XXI,9 A-II,18-19 and P-16 indicates M. erdmani and fall within the range for M. macropus and barely within the range for M. gilli (M. delalandii can match the median-fin ray count but have fewer than 16 pectoral-fin rays). (DNA)

Ecology:
The imitator blenny is a tiny labrisomid rarely noticed by divers. They are not common and prefer shallow rockier habitats than most of their congeners. The species is apparently restricted to the Caribbean Sea and the Bahamas, with no records from Florida, the Gulf of Mexico, or NE Venezuela down to Brazil and its offshore islands. Their larvae are uncommon in collections and, unlike many other reef fishes, most were collected in the dry season in Panama.

Description:
Pre-transitional larvae: Body long, narrow, and thin with a large round eye, pointed snout, and relatively small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. On the head there are a pair of large side-by-side melanophores overlying the midbrain lobes, typically widely spaced (more than a pupil-width apart), sometimes with one or two additional small adjacent spots, but all limited to the the midbrain lobes (nearing transition, one or a few additional small pseudolarval spots can develop on the side of the head and anteriorly). There is a cheek melanophore on each side. There are no melanophores along the base of the dorsal or caudal fins. Along the ventral midline there are notably no melanophores at the isthmus or at the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray (and sometimes the second spine), usually sparing the last ray, followed by a single melanophore placed just after the last ray (sometimes a second) along the ventral midline of the caudal peduncle; it is often slightly more prominent than the preceding row. Internal melanophores comprise only the basic complement: the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: M. erdmani larvae in transition develop patches of small surface melanophores over the head, including a short bar down from the orbital rim at 6:00 o'clock and an eye-stripe from the orbital rim to the mid-maxilla. In addition, the melanophores on the lower rim of the pectoral-fin base form two patches, the anteriormost often a vertical line from under the operculum. Transitional larvae also sometimes develop a few additional small pseudo-larval melanophores over the hindbrain lobes. Fine metamorphic melanophores later extend onto the body. Notably, the cirri that develop on each side of the head, on the nape, over the eye, and over the nasal tube are multifid.

Juveniles: M. erdmani juveniles can be recognized by having a blue-ringed ocellus forming on the body just below the last few dorsal-fin spines, often still part of a dark fourth bar on the body.

Analogues:
Larval M. erdmani (and M. macropus) can be separated from their congeners by their light markings, i.e. the absence of melanophores along the dorsal and caudal-fin bases, none along the anterior ventral midline forward of the anal fin, and fewer than 5 melanophores on top of the head with bare forebrain lobes, i.e. spots only over the midbrain optic lobes and none over the forebrain lobes (between the eyes). M. gilli larvae can appear similar, but have a deep melanophore at the pelvic-fin insertion (and typically additional head melanophores and fewer pectoral-fin rays). M. aurolineatus larvae can have few melanophores on the head, but have additional melanophores along the median-fin bases and at the isthmus and pelvic-fin insertion. Larval M. erdmani are very similar to larval M. macropus in size, shape, and markings. There are some marking differences, with M. erdmani larvae always having (at least) a side-by-side pair of head melanophores while M. macropus often have a single melanophore. The arrangement of melanophores on the ventral midline of the caudal peduncle also differs: M. erdmani larvae usually have a single, often more prominent, melanophore placed just after the last fin ray (when there is a second spot, the two species can overlap), while M. macropus usually have two to four evenly-sized melanophores spaced out along the caudal peduncle; if one, it is most often placed half-way to the procurrent caudal-fin rays. Since most M. erdmani also have fewer anal-fin rays than M. macropus, the total number of melanophores in the ventral row is typically two or three fewer (often 18 vs. 21). Fin-ray counts are generally different and helpful for separation, however there is some overlap requiring DNA sequencing for definitive identification of larvae within the shared range. The D-XXI,9 A-II,18-19 P-16 combination occurs in more than half of M. erdmani individuals but is rare in M. macropus. Certain counts are indicative of M. erdmani: 29 total dorsal-fin elements, i.e. 20 dorsal-fin spines or 21 with only 8 dorsal-fin rays (below Springer's reported range for M. macropus) and the frequent combination of 18 anal-fin soft rays and 16 pectoral-fin rays (characteristic of M. erdmani and rare for M. macropus). Late larvae also diverge in the relative length of their dorsal-fin spines: in M. erdmani the first spine is distinctly longer than the third-to-last spine, while in M. macropus the first spine is about the same length (or less) as the third-to-last spine.

Early transitional M. erdmani larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern. During transition M. erdmani diverge from M. macropus in the number of cirri that develop: in M. erdmani the cirri over the eye and on the nape are bifid or trifid vs. single in M. macropus. During transition M. erdmani also diverge from M. macropus in the relative length of their dorsal-fin spines; the third-to-last spine is much shorter than the first spine, while in M. macropus the several spines before the last become long, often longer than the first.

Juvenile and adult M. erdmani are best recognized by the prominent squared-off ocellus ringed in black and/or blue on the body just below the last few dorsal-fin spines. Juvenile M. gilli have an ocellus at the same location, but it clearly extends onto the fin membranes. Juvenile M. macropus have no ocelli and long single cirri (multiple in M. erdmani).

Diagnosis: The modal fin-ray count of D-XXI,9-10 A-II,20 and P-15 indicates Malacoctenus macropus. This fin-ray count falls within the range for M. erdmani, M. gilli, M. aurolineatus, L. bucciferus, and L. haitiensis. (DNA)

Ecology:
Rosy blennies are the most common labrisomid in the Caribbean and are found in large numbers in all shallow clear-water habitats. They are small, only one or two inches long, and especially abundant in the mixed coral, rubble, sand, and seagrass areas that occupy large areas of hard-bottom shoreline in the region. The species ranges throughout the Caribbean, as well as Bermuda, Florida, and the Gulf of Mexico, but not NE Venezuela or Brazil and its offshore islands. Their larvae are among the ten most commonly collected reef fish larvae and occur in the vast majority of nightlight and plankton-tow collections.

Description:
Pre-transitional larvae: Body long, narrow, and thin with a large round eye, pointed snout, and relatively small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. On the head there are either a pair of large side-by-side melanophores or a single slightly off-center melanophore overlying the midbrain lobes (about a third of larvae with the single spot). The paired spots are often not widely spaced (about a pupil-width apart). Occasionally there are three or four spots, rarely up to six, but typically all are clustered over the midbrain lobes, behind the level of the rear edge of the orbit (nearing transition, one or a few additional small pseudolarval spots can develop on the side of the head and anteriorly). There is a cheek melanophore on each side. There are no melanophores along the base of the dorsal or caudal fins. Along the ventral midline there are notably no melanophores at the isthmus or at the pelvic-fin base. An occasional variant (including about half from one large collection) can have a melanophore along the dorsal midline of the caudal peduncle or at the base of one or a few dorsal-fin soft rays and/or on the side of the body just above the rear anal fin (very rarely a spot or two at the base of the caudal-fin rays). Along the anal fin there is a melanophore at the base of each anal-fin soft ray (and sometimes the second spine), usually sparing the last ray, followed by two to four melanophores spaced out along the ventral midline of the caudal peduncle (occasionally one or none; if one, it is most often placed half-way to the procurrent caudal-fin rays). Internal melanophores comprise only the basic complement: the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: M. macropus larvae in transition develop patches of small surface melanophores over the head, including a short bar down from the orbital rim at 5:30 o'clock and an eye-stripe from the orbital rim to the anterior third of the maxilla. In addition, the melanophores on the lower pectoral-fin base form a short line slanting down and back from under the operculum or, sometimes, a wider horizontal band across the lower fin base. Transitional larvae also sometimes develop a few additional small pseudo-larval melanophores over the midbrain lobes and transitional juveniles often show multiple satellite pseudo-larval melanophores that resemble fragmentation of the large larval melanophores. Fine metamorphic melanophores later extend onto the body forming either complex reticulations in the shape of rows of irregular vertical ovals or uniform shading, typically denser on the upper body. Notably, the long cirri that develop on each side of the head, on the nape, over the eye, and over the nasal tube are single filaments.

Juveniles: M. macropus juveniles have highly variable marking patterns: most often a bicolor pattern of dark above, light below, but often uniformly-shaded or occasionally even prominently barred. Their long single cirri (at the nape, over the eye, and at the nasal tube) on each side are diagnostic.

Analogues:
Larval M. macropus (and M. erdmani) can be separated from their congeners by their light markings, i.e. the absence of melanophores along the dorsal and caudal-fin bases, none along the anterior ventral midline forward of the anal fin, and fewer than 5 melanophores on top of the head with bare forebrain lobes, i.e. spots only over the midbrain optic lobes and none over the forebrain lobes (between the eyes). M. gilli larvae can appear similar, but have a deep melanophore at the pelvic-fin insertion (and typically additional head melanophores and only 20 dorsal-fin spines). M. aurolineatus larvae can have few melanophores on the head, but have additional melanophores along the dorsal and caudal-fin bases and at the isthmus and pelvic-fin insertion. Larval M. erdmani can be very similar to larval M. macropus in size, shape, and markings. Since M. erdmani larvae seem to always have a side-by-side pair of head melanophores, the identification problem only applies to M. macropus larvae with a pair of head melanophores, more than half of the specimens in most samples. The arrangement of melanophores on the ventral midline of the caudal peduncle differs: M. macropus usually have two to four melanophores spaced out along the caudal peduncle after the last fin ray (if one, it is most often placed half-way to the procurrent caudal-fin rays), while M. erdmani larvae usually have a single melanophore very close to the last fin ray, often slightly more prominent than the preceding anal-fin row (occasionally two, then the two species overlap). Since most M. macropus also have more anal-fin rays than M. erdmani, the total number of melanophores in the ventral row is typically two or three more in M. macropus (often 21 vs. 18). Fin-ray counts are generally different and helpful for separation, however there is some overlap requiring DNA sequencing for definitive identification of larvae within the shared range. The D-XXI,9 A-II,18-19 P-16 combination occurs in more than half of M. erdmani individuals, and is rare in M. macropus (especially the 18 anal-fin soft rays). Certain counts are indicative of M. erdmani: 29 total dorsal-fin elements, i.e. 20 dorsal-fin spines or 21 with only 8 dorsal-fin rays (rare, and below Springer's reported range, for M. macropus) and the frequent combination of 18 anal-fin soft rays and 16 pectoral-fin rays (characteristic of M. erdmani and rare for M. macropus). Late larvae also diverge in the relative length of their dorsal-fin spines: in M. macropus the first spine is about the same length (or less) as the third-to-last spine, while in M. erdmani the first spine is distinctly longer than the third-to-last spine.

Early transitional M. macropus larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. the combination of the 5:30 o'clock bar, an eye stripe to the front of the maxilla, and a short line across the pectoral-fin base from under the operculum (two patches in M. erdmani). Transitional larvae develop single cirri on each side of the nape and over the eye, while congeners, including M. erdmani, develop multiple cirri when the new cirri are medium-length. During transition, M. macropus diverge from their congeners in the dorsal-fin outline, with the last several spines long, often longer than the first spine vs. a particularly short third-to-last spine in the other species (in this feature, M. macropus resemble Labrisomus juveniles, although in all other respects, they are typical Malacoctenus).

Juvenile (and adult) M. macropus have a variety of marking patterns, from uniformly shaded (white or rosy) and speckled, to bicolor (dark above, light below), or even prominently barred, and are best distinguished by the long single cirri extending from the nasal tube, eye, and nape vs. multiple, often bushy, sets of cirri on congeners. When barred, the bars do not extend over the anal fin and the two bars under the last dorsal-fin spines meet on the body to form a prominent V or Y.

Diagnosis: Fin-ray counts of D-XX,13 or XXI,11-12 or XXII,11 (a mode of 33 dorsal-fin elements) and modal A-II,22 with 15 pectoral-fin rays indicates Malacoctenus boehlkei. Few congeners match the high dorsal-fin ray count; only a rare M. triangulatus shares the D-XX,13 and a very rare M. macropus has as many as D-XXIII,10 and/or A-II,22. Labrisomus filamentosus share the high median-fin ray count, but have only 13 pectoral-fin rays (and a quite different morphology). L. haitiensis barely overlaps the count, with a rare D-XXII,11 and/or A-II,22. (DNA)

Ecology:
The diamond blenny is a tiny blenny typically found on coral walls and slopes below 30 feet; it is the only deeper-water Malacoctenus species and often shelters among anemone tentacles. The species ranges from Florida, the S. Gulf of Mexico, and the Bahamas across the Caribbean Sea, but not NE Venezuela or Brazil and its offshore islands. Their larvae are unknown or unrecognized in collections.

Description: (larvae unknown, description inferred from transitional juvenile)
Larvae: Body long, narrow, and thin with a large round eye, pointed snout, and relatively small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins very long and thread-like. On the head there are several large and small melanophores per side, over both the fore- and midbrain lobes. Along the anal fin there is a melanophore at the base of each anal-fin soft ray.

Juveniles: M. boehlkei recruits develop a distinctive yellow-ringed ocellus on the first three dorsal-fin-spine membranes, not contacting the body. Their two longest pelvic-fin rays are greatly extended, reaching to the mid-anal fin.

Analogues:
Once they develop the characteristic ocellated spot at the front of the spinous dorsal fin, recruits can be separated from all other labrisomid species. M. triangulatus and M. gilli both have a dark non-ocellated spot on the first dorsal-fin spines, located lower on the fin and extending onto the body.

Diagnosis: The modal fin-ray count of D-XVIII,11 A-II,18 and P-13 indicates Labrisomus albigenys and L. nigricinctus. This fin-ray count falls within the lower range for Malacoctenus aurolineatus and M. versicolor, as well as for many of the remaining 18 and 19-spined Labrisomus. (DNA)

Ecology:
The white-cheek blenny is a rare species, with few collections and no live photographs. They are found sporadically throughout the Caribbean Sea, as well as in the Bahamas and the Yucatan, but not farther into the Gulf of Mexico or in Florida, Bermuda, NE Venezuela, or Brazil and its offshore islands. Their larvae are rare in collections.

Description:
Pre-transitional larvae: Body long, moderately narrow, and thin with a large round eye, pointed snout, and medium-sized terminal mouth. Long continuous dorsal and anal fins with a very short and relatively narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. On the head there are a pair of large side-by-side melanophores overlying the midbrain lobes and smaller melanophores, either one off-center or a pair, over the forebrain lobes. The cheek melanophores are apparently absent on the three larvae identified. There are no melanophores along the base of the dorsal or caudal fins, although one specimen has one and two melanophores on the sides of the body just lateral to the base of the last dorsal-fin spines (perhaps transitional). Along the ventral midline there is a melanophore at the isthmus and deep at the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray (sometimes at the second spine as well). In addition, there is a variably-placed large melanophore near the base of the 14th anal-fin soft ray, sometimes at the base of the ray and extending into the musculature, but sometimes located subsurface in the body some distance away from the base of the fin ray. There are no melanophores along the ventral midline of the caudal peduncle. Internal melanophores comprise only the basic complement: the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. albigenys larvae in transition develop diffuse areas of fine surface melanophores over the top and side of the head, not in defined patches. A pale bar develops across the cheek from 4-5 o'clock on the orbital rim. The species apparently develops metamorphic melanophores over the head first, unlike most Labrisomus species. Cirri develop on each side of the head, on the nape (relatively stubby), over the eye (delayed), and over the nasal tube. One larva caught at a light at night had a fully-scaled body before developing metamorphic melanophores.

Juveniles: L. albigenys juveniles have no opercular ocellus (or dark spot) and usually an anterior dorsal-fin spot. They have a prominent pale patch on the cheek below the eye (4-6 o'clock from the orbit) outlined by two dark lines.

Analogues:
Larval L. albigenys can be distinguished from congeners by the prominent enlarged melanophore in or near the posterior anal-fin base series (internal into the musculature or sub-surface on the body near the series). A similar kind of melanophore can be found in the anal-fin base series of some Starksia larvae, however they all have fewer than 9 dorsal-fin soft rays. L. albigenys larvae share their small size, relatively small terminal mouth, and dorsal-fin outline (short first spine and short posterior spines), with the larvae of L. nigricinctus and some Malacoctenus. L. albigenys larvae are very similar to larval L. nigricinctus in both morphology and fin-ray counts, and can best be separated by the enlarged or deep anal-fin melanophore and perhaps by having no melanophores on the ventral caudal peduncle (vs. one). L. albigenys larvae are separated from Malacoctenus by melanophore pattern and fin-ray counts. Only M. gilli larvae occasionally share the pattern of a pair over the midbrain lobes and one or a pair over the forebrain lobes, but M. gilli larvae have no isthmus melanophores. M. erdmani and M. macropus can have similarly few head spots, but they are over the midbrain lobes only and they have no anterior ventral midline spots. Only rare individuals of M. aurolineatus and M. versicolor share the low median and pectoral-fin ray counts of L. albigenys and both have different arrangements of head melanophores: the former with a midline melanophore over the midbrain lobes and additional melanophores along the soft dorsal and caudal-fin bases and the latter with many more head spots. Larvae of the remaining Labrisomus species have more head spots, at least five in a U- or V-shape, relatively longer posterior dorsal-fin spines (vs. soft rays), and are generally larger at transition.

Transitional L. albigenys larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. the metamorphic melanophores on the head are diffusely distributed with only a pale bar across the cheek. Transitional L. nigricinctus are unknown, but probably do not share the persistent enlarged or deep anal-fin melanophore and the head melanophore distribution. L. albigenys are separated from transitional Malacoctenus by having stubs of nuchal cirri and not having clearly delineated patches of metamorphic melanophores on the head. The remaining Labrisomus species develop metamorphic melanophores over the head and body simultaneously, have more larval head melanophores, and relatively longer posterior dorsal-fin spines.

L. albigenys juveniles have a uniform dark head with a pale patch on the cheek under the eye, usually outlined by two dark lines, although a similar pattern is common to lesser degrees among many Labrisomus species. Juvenile Malacoctenus all have well-outlined and distinctive head markings. The dorsal-fin outline, with the short first spine and very short penultimate spine relative to the soft rays, separates L. albigenys juveniles from several other Labrisomus species (except L. nigricinctus, L. guppyi and, to a degree, L. gobio). The XVIII,11 or fewer dorsal-fin elements also helps to distinguish less-marked L. albigenys juveniles from occasional lightly-marked juveniles of other Labrisomus species, although a few can range down to overlap. The absence of a dark spot or ocellus on the operculum separates L. albigenys from the other 18-spined species: L. nigricinctus and L. nuchipinnis, L. conditus, and L. cricota (which all also have longer snouts, more than two-thirds the bony orbit diameter). The 19- and 20-spined Labrisomus species share the blunter snout with juvenile L. albigenys (less than two-thirds the bony orbit diameter), but only rarely have so few median fin-rays. L. albigenys early juveniles also have been described to have only two nasal cirri and one long simple orbital cirrus per side (more or branched in the other Labrisomus and Malacoctenus species, except M. macropus).

Diagnosis: The modal fin-ray count of D-XVIII,11 A-II,18 and P-13 indicates Labrisomus nigricinctus and L. albigenys. This fin-ray count falls within the lower range for Malacoctenus aurolineatus and M. versicolor, as well as for many of the remaining 18 and 19-spined Labrisomus species. (DNA)

Note: This larval identification is pending DNA confirmation, but is likely from the process of elimination: the larva differs in several ways from the L. albigenys series described above (the L. albigenys identification is based on the fin-ray counts and a very different DNA sequence from adult L. nigricinctus from the same site). The remaining species of Labrisomus and Malacoctenus that could possibly share the low fin-ray count of this larva have different larvae, all clearly identified here with DNA-sequence confirmation. The remarkably small size of the larva (for Labrisomus) matches the observation by Springer (1959) that juvenile L. nigricinctus as small as 12 mm SL are collected on the reef.

Ecology:
The spotcheek blenny is a small blenny found mostly in tidepools and shallow eroded reef and thus rarely noticed underwater. They are found throughout the Caribbean, as well as Florida, the Gulf of Mexico, and the Bahamas, but not NE Venezuela or Brazil and its offshore islands. The species is common only in clear water and high-energy sites: the outer Keys in Florida, the Bahamas and Antilles, and the barrier reef and atolls of Belize. Their larvae are rare in collections.

Description:
Pre-transitional larvae: Body long, moderately narrow, and thin with a medium round eye, pointed snout, and relatively small terminal mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like. On the head there are two small off-center melanophores overlying the midbrain lobes. There is a cheek melanophore on each side. There are no melanophores along the dorsal or caudal-fin bases. Along the ventral midline there is a melanophore at the isthmus and deep at the pelvic-fin base. Along the anal fin there is a melanophore at the base of each anal-fin soft ray except the last, which is closely followed by a single larger melanophore along the ventral midline of the caudal peduncle. Internal melanophores comprise only the basic complement: the nuchal midline, otic capsule, and overlying the abdominal organs.

Juveniles: L. nigricinctus juveniles are quite distinctive with a prominent round opercular ocellus, a pointed snout with a small terminal mouth, no spot on the first few dorsal-fin spines, and sometimes narrow dark bars on the body that extend onto the dorsal fin.

Analogues:
L. nigricinctus larvae share fin-ray counts and some morphology with L. albigenys, but differ by having a melanophore along the ventral midline of the caudal peduncle, one or two cheek melanophores, and no deep melanophore associated with the anal-fin row. These two species are intermediate in size and appearance between Labrisomus and Malacoctenus, but, notably, have lower fin-ray counts than all Malacoctenus except the rare individual of M. versicolor or M. aurolineatus. Larvae of M. versicolor can be distinguished by their relatively long first dorsal-fin spines (vs. short in the two Labrisomus species) and more numerous head spots. M. aurolineatus larvae also have a longer first dorsal-fin spine and have a set of additional larval melanophores (along the soft dorsal-fin and caudal-fin bases and internally over the vertebral column). M. macropus, M. erdmani and M. gilli larvae have similar light markings, but no melanophore at the isthmus (or the pelvic-fin base in the former two) and higher fin-ray counts. The remaining Malacoctenus species have many more head spots. The remaining Labrisomus larvae are larger with larger mouths and usually with many more melanophores over the cranium, dorsal and caudal-fin bases, and internally over the vertebral column.

Juvenile L. nigricinctus are separated from other Labrisomus species by the small mouth, pointed snout, and well-delineated round opercular ocellus. In morphology they appear more similar to Malacoctenus juveniles, however no Malacoctenus share the obvious ocellus on the operculum. Juvenile L. nuchipinnis, L. guppyi, and L. filamentosus can share the opercular ocellus, but are distinguished by less-pointed snouts, larger mouths, and indistinct bars. The 19- and 20-spined Labrisomus species all have a much blunter snout, less than two-thirds the bony orbit diameter.

Diagnosis: The modal fin-ray count of D-XVIII,12 A-II,18 and P-14 is shared by Labrisomus nuchipinnis and the related cryptic species L. conditus and L. cricota, as well as by Malacoctenus versicolor. The fin-ray count falls within the lower range for L. guppyi and L. kalisherae and the upper range for L. albigenys and L. nigricinctus. (DNA)

Ecology:
The true hairy blenny is the largest member of its family in the region (adults can reach more than six inches long) and they are the most commonly encountered species of Labrisomus. They occupy a variety of shallow-water habitats, but are usually found in mixed coral and rocky substrates. The recent discovery of two additional allied cryptic species described from Brazil but widespread in the region complicates identifications within the group. L. nuchipinnis is very widely distributed: from Bermuda, Florida, the entire Gulf of Mexico, the Bahamas, as well as all of the Caribbean Sea including NE Venezuela to Brazil and some of its offshore islands. They are apparently replaced on Noronha by L. conditus and share the Brazilian coast with L. cricota. True hairy blennies vary greatly in markings and colors, with some overlap in appearance with the cryptic species, although many smaller specimens (and all juveniles?) show the sharp and narrow white rim around a rounded opercular ocellus that likely confirms the ID as L. nuchipinnis. However, when the ocellus is not round, or not well-delineated by a thin white ring, or the white ring is broken, or there is no ocellus, the marking does not separate species (I have found DNA-confirmed adult L. nuchipinnis can have any or all of these patterns, including a mix of any version on each side of the fish). Morphological characters that separate the adults are published for Brazilian populations and depend on relative lengths of the first dorsal-fin spines and the nuchal cirri and remain to be confirmed for juveniles and Caribbean populations. Sequencing results thus far show that at locations outside Brazil, L. nuchipinnis well outnumber the cryptic species (or are the only species). L. nuchipinnis barcode DNA sequences vary little over the entire region from Bermuda to Brazil. Their larvae are occasional in collections.

Description:
Pre-transitional larvae: Body long, narrow, and thin, with a medium eye, pointed snout, and terminal medium-sized mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like; the third pelvic-fin ray is about 3/4 the length of the second. There are some small spines along the rim of the preoperculum that no longer project as larvae approach and complete transition. The full complement of large melanophores on the top of the head typically consists of a row of three on each side of the head, usually in a narrow-U, i.e. the spots get closer to the dorsal midline anteriorly; quite often there are just five (rarely 7) in a V with a single melanophore at the vertex at or near the midline of the forebrain (note that in both cases the rear side-by-side pair are typically more widely spaced than the middle pair). Often there is an additional near-surface melanophore at the midline behind the mid-brain lobes, completing a narrow-O (not the deep nuchal midline melanophore). There can sometimes be one or, uncommonly, a few smaller additional melanophores. There are no melanophores just behind the tip of the upper jaw, but there can be a small melanophore at the anterior nostril on each side. There is a cheek melanophore on each side. There is a prominent melanophore, or sometimes a few, on the inner aspect of the cleithrum visible within the gill cavity on each side. Melanophores run along the base of all of the soft dorsal-fin rays and some of the dorsal-fin spines, typically including some anterior spines, usually starting at spine 8 (can be at 5 or even 2), then 11-12, and from 14 rearward. A few individuals develop a small melanophore along the dorsal midline of the caudal peduncle. A small melanophore is often located on the body at the lateral midline on the caudal peduncle. A vertical line of melanophores develops along the base of the caudal-fin segmented rays (first proximal, then distal) and thin linear melanophores are spaced out along each side outlining the full-length of the three lower caudal-fin segmented rays (occasionally a few along the upper three rays as well). Along the ventral midline there are melanophores at the isthmus and deep behind the pelvic-fin base. There is occasionally a small melanophore or two at the surface on the ventral aspect of the abdomen, but no extensive speckling of the peritoneum is visible from below. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, followed by one, sometimes two, along the ventral midline of the caudal peduncle. A row of internal melanophores overlies the vertebral column, spaced about every third vertebra, along the mid- and rear body, continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. nuchipinnis larvae develop metamorphic melanophores over the head and body simultaneously. The head is mostly uniformly speckled or reticulated with fine melanophores while the body is uniformly reticulated with a network of thin lines not separated into bars. As in other Labrisomus, the prominent head melanophores begin to shrink, spread, or fragment into smaller spots, or narrow into short lines (usually the middle pair); later they are obscured by underlying speckling and overlying shading.

Juveniles: L. nuchipinnis juveniles develop a pattern of reticulations and dark bars on the body, an opercular ocellus, usually fully rounded with a complete thin white rim, and a dark spot on the first three dorsal-fin spine membranes. Juvenile blennies of this group can vary greatly in the degree of these dark markings; some light individuals intensify their white spots and fade, or sort of pixelate, their melanocytes, while others are darkly-reticulated and some can be almost uniformly dark.

Analogues:
Pretransitional L. nuchipinnis are probably identical to the larvae of the cryptic species L. conditus and L. cricota. Although the first dorsal-fin spine is shorter than the third in adult L. nuchipinnis and L. conditus vs. longer in L. cricota, DNA-confirmed L. nuchipinnis larvae can have equal-length anterior dorsal-fin spines and it is likely that the fin-spine differences only emerge at or after transition. Larvae of the other 18-spined species, L. albigenys and L. nigricinctus, have many fewer melanophores on the head and usually none at the dorsal and caudal-fin bases. L. haitiensis larvae share the slim morphology with L. nuchipinnis larvae as well as the row of melanophores along the spinous dorsal-fin base including some of the first 10 spines, and, to varying degrees, most of the other markings of larval L. nuchipinnis, but they can be distinguished by a short and inconspicuous third pelvic-fin ray, a pair of melanophores behind the tip of the upper jaw (absent on L. nuchipinnis larvae), extensive speckling of the ventral abdominal viscera visible through the abdominal wall, the absence of inner cleithral melanophores, and higher fin-ray counts. The remaining Labrisomus species usually have an unmarked spinous dorsal-fin base or, at most, melanophores extending only to some of the spines of the rear half of the spinous dorsal-fin. Those with more melanophores typically have the pair of melanophores behind the tip of the upper jaw (absent on L. nuchipinnis larvae) as well as additional melanophores on top of the head, multiple in each quadrant (vs. the basic U or V-pattern on L. nuchipinnis), and rarely have the inner cleithral melanophores. Lightly marked specimens can be problematic because they are often missing the pair at the tip of the jaw and share the basic U or V-pattern of L. nuchipinnis; in that case they can be distinguished by the absence of the inner cleithral melanophores and the absence of the melanophores lining the lower caudal-fin segmented rays (or, rarely, a very few at the proximal ends of the rays).

L. nuchipinnis larvae can resemble large Malacoctenus larvae since they are relatively slim and have smaller mouths than some other large Labrisomus species. Nevertheless, the row of melanophores along some of the spinous dorsal-fin base separates L. nuchipinnis from all Malacoctenus larvae other than the occasional variant specimen of M. triangulatus. The latter, however, do not have melanophores outlining the caudal-fin segmented rays or the central caudal peduncle spot and usually have more numerous and graded-size head spots (as well as higher median-fin ray counts, a short third pelvic-fin ray, and a different dorsal-fin outline, with short posterior spines).

Transitional L. nuchipinnis larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. a uniform pattern of fine reticulations. The other Labrisomus species develop uniform shading or bars, except for the two allied cryptic species which share the reticulations of L. nuchipinnis: transitional L. cricota may be distinguished by the first dorsal-fin spine being longer than the third, and transitional L. conditus probably cannot be separated until the oval dark spot develops on the operculum. L. nuchipinnis are also separated from transitional Malacoctenus larvae by having shorter cirri (especially orbital), the fine metamorphic melanophores on the head mostly diffusely distributed (vs. in discrete patches) and developing at the same time as body markings (vs. head first), and the dorsal-fin outline.

Juvenile L. nuchipinnis are separated from most other labrisomids by the long snout, anterior dorsal fin spot, and a thin-edged rounded opercular ocellus. Juveniles of L. conditus and L. cricota share the anterior dorsal-fin spot and body reticulations and bars, but apparently do not have a round well-delineated opercular ocellus: juvenile L. conditus have an oval and not sharply-outlined ocellus on the operculum and L. cricota have a diffusely broad and orange edge to the opercular ocellus and the first two dorsal-fin spines distinctly longer than the third (vs. equal or shorter in the other two species). Two other Labrisomus have a well-outlined ocellus, L. nigricinctus and L. filamentosus, but the former have narrow bars and a very pointed snout and the latter have the first three dorsal-fin spines greatly extended and higher median-fin ray counts. Two other species have a less well-outlined ocellus: L. guppyi, with no dorsal-fin spot, a blunt snout, and 19 dorsal-fin spines; and L. haitiensis, with the opercular spot not outlined as an ocellus, a blunt snout, an inconspicuous third pelvic-fin ray, and 20 dorsal-fin spines. The 19- and 20-spined Labrisomus species all have a blunt snout, less than two-thirds the bony orbit diameter. Juvenile Malacoctenus all have pointier snouts with smaller mouths, have very short posterior dorsal-fin spines (except M. macropus), and none have a well-outlined opercular ocellus.

Diagnosis: The modal fin-ray count of D-XVIII,12 A-II,18 and P-14 is shared by Labrisomus conditus and the related cryptic species L. nuchipinnis and L. cricota, as well as by Malacoctenus versicolor. The fin-ray count falls within the lower range for L. guppyi and L. kalisherae and the upper range for L. nigricinctus and L. albigenys. (DNA)

Ecology:
The masquerader hairy blenny was recently described as the endemic hairy blenny from the Brazilian offshore island of Fernando de Noronha by Sazima, Carvalho-Filho, Gasparini & Sazima (2009). However, my barcode DNA surveys show that the same species has been collected by me in Panama and there is a match to a specimen collected in Florida as well. Although the original description notes some marking differences from the two other cryptic species and shorter nuchal cirri in L. conditus, it is uncertain whether these apply throughout the wide shared range (or to juveniles). L. conditus are supposed to have a less well-developed opercular ocellus with an incomplete and wide orange rim and a profusion of small blue spots over the head and body. However, true hairy blennies (with DNA sequence confirmation) vary greatly in markings and colors and some adults can overlap in appearance with the cryptic species (although many have a narrowly-delineated rounded opercular ocellus). A transitional juvenile Panamanian L. conditus has a distinctive oval-shaped opercular ocellus that is not sharply outlined, however the consistency of this mark is uncertain. L. conditus larvae are unknown or unrecognized in collections.

Description:
(based on the transitional specimen, larval patterns are identical to L. nuchipinnis)
Body long, narrow, and thin, with a medium eye, pointed snout, and terminal medium-sized mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like; the third pelvic-fin ray is about 3/4 the length of the second. There are some small spines along the rim of the preoperculum that no longer project as larvae approach and complete transition. The full complement of large melanophores on the top of the head typically consists of a row of three on each side of the head, usually in a narrow-U, i.e. the spots get closer to the dorsal midline anteriorly; quite often there are just five (rarely 7) in a V with a single melanophore at the vertex at or near the midline of the forebrain (note that in both cases the rear side-by-side pair are typically more widely spaced than the middle pair). Often there is an additional near-surface melanophore at the midline behind the mid-brain lobes, completing a narrow-O (not the deep nuchal midline melanophore). There can sometimes be one or, uncommonly, a few smaller additional melanophores. There are no melanophores just behind the tip of the upper jaw, but there can be a small melanophore at the anterior nostril on each side. There is a cheek melanophore on each side. There is a prominent melanophore, or sometimes a few, on the inner aspect of the cleithrum visible within the gill cavity on each side. Melanophores run along the base of all of the soft dorsal-fin rays and some of the dorsal-fin spines, typically including some anterior spines, usually starting at spine 8 (can be at 5 or even 2), then 11-12, and from 14 rearward. A few individuals develop a small melanophore along the dorsal midline of the caudal peduncle. A small melanophore is often located on the body at the lateral midline on the caudal peduncle. A vertical line of melanophores develops along the base of the caudal-fin segmented rays (first proximal, then distal) and thin linear melanophores are spaced out along each side outlining the full-length of the three lower caudal-fin segmented rays (occasionally a few along the upper three rays as well). Along the ventral midline there are melanophores at the isthmus and deep behind the pelvic-fin base. There is occasionally a small melanophore or two at the surface on the ventral aspect of the abdomen, but no extensive speckling of the peritoneum is visible from below. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, followed by one, sometimes two, along the ventral midline of the caudal peduncle. A row of internal melanophores overlies the vertebral column, spaced about every third vertebra, along the mid- and rear body, continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. conditus larvae develop metamorphic melanophores over the head and body simultaneously. The head is mostly uniformly speckled or reticulated with fine melanophores while the body is uniformly reticulated with a network of thin lines not separated into bars. As in other Labrisomus, the prominent head melanophores begin to shrink, spread, or fragment into smaller spots, or narrow into short lines (usually the middle pair); later they are obscured by underlying speckling and overlying shading.

Juveniles: L. conditus develop a pattern of reticulations and dark bars on the body, a dark oval ocellus without a sharp outline on the operculum, and a dark spot on the first three dorsal-fin spine membranes. Juvenile blennies of this group can vary greatly in the degree of these dark markings; some light individuals intensify their white spots and fade, or sort of pixelate, their melanocytes, while others are darkly-reticulated and some can be almost uniformly dark.

Analogues:
Pretransitional L. conditus are probably identical to the larvae of the cryptic species L. nuchipinnis and L. cricota. Although the first dorsal-fin spine is shorter than the third in adult L. conditus and L. nuchipinnis vs. longer in L. cricota, it is likely that the fin spine differences only emerge at or after transition. L. conditus larvae can resemble large Malacoctenus larvae since they have thinner heads (side-to-side), smaller eyes, and smaller mouths than most other large Labrisomus species. Nevertheless, the melanophore row along the base of some of the spinous dorsal fin separates L. conditus larvae from all Malacoctenus larvae other than the occasional variant specimen of M. triangulatus. The latter, however, do not have melanophores outlining the caudal-fin segmented rays or the central caudal peduncle spot and usually have more numerous and graded-size head spots (as well as higher median-fin ray counts, a short third pelvic-fin ray, and a different dorsal-fin outline, with short posterior spines). L. haitiensis larvae have a similar slim morphology and share the row of melanophores along some of the spinous dorsal-fin base and, to varying degrees, most of the other markings of larval L. conditus, but they can be distinguished by a short and inconspicuous third pelvic-fin ray, a pair of melanophores behind the tip of the upper jaw (apparently absent on L. conditus larvae), and higher fin-ray counts.

Transitional L. conditus larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. a uniform pattern of fine reticulations. They are also separated from transitional Malacoctenus larvae by having shorter cirri (especially orbital), the fine metamorphic melanophores on the head mostly diffusely distributed (vs. in discrete patches), as well as developing at the same time as body markings (vs. head first), and the dorsal-fin outline (relatively longer posterior spines). The other Labrisomus species develop uniform shading or bars, except for the two allied cryptic species which share the reticulations of L. conditus: transitional L. cricota may be distinguished by the first dorsal-fin spine being longer than the third, and transitional L. nuchipinnis probably can only be separated when they develop their well-outlined rounded opercular ocellus.

Juvenile L. conditus are separated from most other labrisomids by the long snout, anterior dorsal fin spot, dark reticulations on the body, and an oval opercular ocellus that is not sharply outlined. L. nuchipinnis, L. nigricinctus, and L. filamentosus have a well-outlined rounded ocellus. Other Labrisomus juveniles with a dark spot on the operculum include the cryptic species L. cricota, which share most markings but have a diffusely broad and orange edge to the opercular ocellus and the first two dorsal-fin spines distinctly longer than the third (vs. equal or shorter in the other two species); L. guppyi, with no dorsal-fin spot; and L. haitiensis, with no dorsal-fin spot and a short third pelvic fin ray. The 19- and 20-spined Labrisomus species can be separated by higher fin-ray counts and blunter snouts, less than two-thirds the bony orbit diameter.

Diagnosis: The modal fin-ray count of D-XVIII,12 A-II,18 and P-14 is shared by Labrisomus cricota and the related cryptic species L. nuchipinnis and L. conditus, as well as by Malacoctenus versicolor. The fin-ray count falls within the lower range for L. guppyi and L. kalisherae and the upper range for L. nigricinctus and L. albigenys. (DNA)

Ecology:
The mock hairy blenny was recently described as endemic to the mainland coast of Brazil by Sazima, Gasparini & Leao de Moura (2002). However, my barcode DNA surveys show that the same species has been collected by me in Panama and there is a match to a specimen collected in Yucatan as well. Although the original description notes some marking differences among the cryptic species and the first two dorsal-fin spines longer than the third and longer nuchal cirri in L. cricota, it is uncertain whether these apply consistently throughout the wide shared range. L. cricota are supposed to have a less well-developed opercular ocellus with a wide and diffuse orange rim, however true hairy blennies (with DNA sequence confirmation) vary greatly in markings and colors and some adults can overlap in appearance with the cryptic species (although many have a narrowly-delineated rounded opercular ocellus). L. cricota larvae are rare in collections.

Description:
(based on the transitional specimen, larval patterns are identical to L. nuchipinnis)
Body long, narrow, and thin, with a medium eye, pointed snout, and terminal medium-sized mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like; the third pelvic-fin ray is about 3/4 the length of the second. There are some small spines along the rim of the preoperculum that no longer project as larvae approach and complete transition. The full complement of large melanophores on the top of the head typically consists of a row of three on each side of the head, usually in a narrow-U, i.e. the spots get closer to the dorsal midline anteriorly; quite often there are just five (rarely 7) in a V with a single melanophore at the vertex at or near the midline of the forebrain (note that in both cases the rear side-by-side pair are typically more widely spaced than the middle pair). Often there is an additional near-surface melanophore at the midline behind the mid-brain lobes, completing a narrow-O (not the deep nuchal midline melanophore). There can sometimes be one or, uncommonly, a few smaller additional melanophores. There are no melanophores just behind the tip of the upper jaw, but there can be a small melanophore at the anterior nostril on each side. There is a cheek melanophore on each side. There is a prominent melanophore, or sometimes a few, on the inner aspect of the cleithrum visible within the gill cavity on each side. Melanophores run along the base of all of the soft dorsal-fin rays and some of the dorsal-fin spines, typically including some anterior spines, usually starting at spine 8 (can be at 5 or even 2), then 11-12, and from 14 rearward. A few individuals develop a small melanophore along the dorsal midline of the caudal peduncle. A small melanophore is often located on the body at the lateral midline on the caudal peduncle. A vertical line of melanophores develops along the base of the caudal-fin segmented rays (first proximal, then distal) and thin linear melanophores are spaced out along each side outlining the full-length of the three lower caudal-fin segmented rays (occasionally a few along the upper three rays as well). Along the ventral midline there are melanophores at the isthmus and deep behind the pelvic-fin base. There is occasionally a small melanophore or two at the surface on the ventral aspect of the abdomen, but no extensive speckling of the peritoneum is visible from below. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, followed by one, sometimes two, along the ventral midline of the caudal peduncle. A row of internal melanophores overlies the vertebral column, spaced about every third vertebra, along the mid- and rear body, continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. cricota larvae develop metamorphic melanophores over the head and body simultaneously. The head is mostly uniformly speckled or reticulated with fine melanophores while the body is uniformly reticulated with a network of thin lines not separated into bars. As in other Labrisomus, the prominent head melanophores begin to shrink, spread, or fragment into smaller spots, or narrow into short lines (usually the middle pair); later they are obscured by underlying speckling and overlying shading.

Juveniles: L. cricota develop a pattern of reticulations and dark bars on the body, a dark spot on the first three dorsal-fin spine membranes, and a diffusely broad orange-outlined opercular ocellus. Juvenile blennies of this group can vary greatly in the degree of these dark markings; some light individuals intensify their white spots and fade, or sort of pixelate, their melanocytes, while others are darkly-reticulated and some can be almost uniformly dark.

Analogues:
Pretransitional L. cricota are probably identical to the larvae of the cryptic species L. nuchipinnis and L. conditus. As larvae approach transition, the first dorsal-fin spine becomes longer than the third in L. cricota vs. shorter or equal in L. nuchipinnis and L. conditus. L. cricota larvae can resemble large Malacoctenus larvae since they have thinner heads (side-to-side), smaller eyes, and smaller mouths than most other large Labrisomus species. Nevertheless, the melanophore row along the base of some of the spinous dorsal fin separates L. cricota larvae from all Malacoctenus larvae other than the occasional variant specimen of M. triangulatus. The latter, however, do not have melanophores outlining the caudal-fin segmented rays or the central caudal peduncle spot and usually have more numerous and graded-size head spots (as well as higher median-fin ray counts, a short third pelvic-fin ray, and a different dorsal-fin outline, with short posterior spines). L. haitiensis larvae have a similar slim morphology and share the row of melanophores along some of the spinous dorsal-fin base and, to varying degrees, most of the other markings of larval L. cricota, but they can be distinguished by a short and inconspicuous third pelvic-fin ray, a pair of melanophores behind the tip of the upper jaw (apparently absent on L. cricota larvae), and higher fin-ray counts.

Transitional L. cricota larvae are distinguished by fin-ray counts, persistent larval melanophores, and their metamorphic melanophore pattern, i.e. a uniform pattern of fine reticulations. They are also separated from transitional Malacoctenus larvae by having shorter cirri (especially orbital), the fine metamorphic melanophores on the head mostly diffusely distributed (vs. in discrete patches) and developing at the same time as body markings (vs. head first), and the dorsal-fin outline. The other Labrisomus species develop uniform shading or bars, except for the two allied cryptic species which share the reticulations of L. cricota: transitional L. nuchipinnis and L. conditus are best distinguished by the first dorsal-fin spine being shorter than or equal to the third.

Juvenile L. cricota are separated from most other labrisomids by the anterior dorsal fin spot and a diffusely broad orange-outlined opercular ocellus. L. nuchipinnis, L. nigricinctus, and L. filamentosus have a well-outlined rounded ocellus. Other Labrisomus juveniles with a dark spot on the operculum include the cryptic species L. conditus, which have most of the same markings but the first dorsal-fin spine is shorter than or equal to the third (vs. longer); L. guppyi, with no dorsal-fin spot; and L. haitiensis, with no dorsal-fin spot and a short third pelvic fin ray. The 19- and 20-spined Labrisomus species can be separated by higher fin-ray counts and blunter snouts, less than two-thirds the bony orbit diameter.

Diagnosis: The modal fin-ray count of D-XIX,11 A-II,19 and P-13 is shared by the 19-spined trio of L. gobio, L. guppyi, and L. kalisherae, as well as by Malacoctenus aurolineatus (but the latter usually with 14 pectoral-fin rays). Note that almost 90% of L. gobio individuals have 19 dorsal-fin spines. The fin-ray count falls within the upper or lower range for most other Labrisomus species and both M. delalandii and M. gilli. (DNA)

Ecology:
The palehead blenny is a somewhat common small blenny found generally in shallow mixed coral habitats. The species is widespread in the region, found in Florida, the S. Gulf of Mexico, the Bahamas, and across the Caribbean Sea except NE Venezuela. Unfortunately, the 19, 20, and 21-spined Labrisomus are very similar morphologically and are frequently confused in guidebooks and photographs. All six species share the blunt-headed and goggle-eyed appearance, at least as juveniles, i.e. the snout length (bony orbit to jaw tip) is less than two-thirds of the orbit diameter. Adult palehead blennies are recognized in the field mostly by the absence of an opercular ocellus, the dark bars not extending onto the fins, and relatively even-length dorsal-fin spines. Additional characters often cited are an "unmarked" lower head and the lower portion of the bars on the body being lighter and narrower than the upper parts, although the variation in the intensity of markings in the group make these unreliable. Juveniles are particularly difficult to separate, since the distinguishing markings for each species are either not well-developed or shared by other species at this early stage (but see description below). L. gobio larvae are rare in collections.

Description:
(pre-transitional larvae have not been identified, but are likely identical among the 19-spined Labrisomus, see L. guppyi)

Transitional stage: L. gobio larvae in transition develop metamorphic melanophores over the head and body simultaneously. The head is mostly uniformly speckled with fine melanophores; on the body there is a series of about 9 dark bars, alternating lighter and darker, with unpigmented bands between them.

Juveniles: L. gobio juveniles have prominent dark bars on the body that do not extend onto the fins, with the second body bar (under the 10-15th dorsal-fin spines) widening on the upper body to touch the bases of about 5 or 6 spines. The last dark bar, on the tail, ends as a straight vertical line or slight crescent. Although there can be a dark spot on the operculum, it is not an ocellus with a thin rim. The first dorsal-fin spine is relatively long, about half the body depth at the dorsal-fin origin, and similar in length to the mid-fin spines.

Analogues:
The juveniles of the 19- and 20-spined Labrisomus are blunt-headed, compared to the 18-spined Labrisomus (other than L. albigenys), i.e. the snout length (bony orbital margin to the tip of the closed jaw) is less than two-thirds the bony orbit diameter. Small juveniles of the blunt-headed Labrisomus are difficult to identify to species, especially since some species described with opercular ocelli can have only a diffuse dark spot on the operculum when young. In addition, those species described without ocelli can often have an outlined dark spot on the operculum (but not a thin-rimmed ocellus) as juveniles.

Juvenile L. gobio are best identified by the dark bars on the body that do not extend onto the fins and the second body bar widening to reach about 5 or 6 dorsal spine bases (vs. 3 or 4 in other species). They can be further separated from L. guppyi juveniles who have not yet developed a distinct opercular ocellus by a longer first dorsal-fin spine (2 to 2.5 into body depth at the dorsal-fin origin vs. 2.5 to 3) and fewer dark bands on the pelvic fins (often faint and no more than 4). Juvenile L. kalisherae share the long first dorsal-fin spine but have the pigment on the base of the caudal fin outlining three light spots vs. ending as a mostly straight vertical line in L. gobio (and L. guppyi). Juvenile L. bucciferus and L. haitiensis also have three outlined spots on the caudal-fin base (and even longer first dorsal-fin spines and higher fin-ray counts). L. albigenys are best distinguished by their very short first dorsal-fin spine and lower fin-ray counts. The remaining Labrisomus juveniles are distinguished from L. gobio by longer snouts, opercular ocelli, and fin-ray counts, i.e. L. nigricinctus and L. nuchipinnis (as well as L. conditus and L. cricota, both with less distinct ocelli), and L. filamentosus (blunt-snouted but with longer first dorsal-fin spines).

Diagnosis: The modal fin-ray count of D-XIX,11 A-II,19 and P-13 is shared by the 19-spined trio of L. guppyi, L. gobio, and L. kalisherae, as well as by Malacoctenus aurolineatus (but usually with 14 pectoral-fin rays). Note that almost 90% of L. guppyi individuals have 19 dorsal-fin spines. The fin-ray count falls within the upper or lower range for most other Labrisomus species and both M. delalandii and M. gilli. (DNA)

Ecology:
The mimic blenny is a somewhat common small blenny found mostly under rocks and in shallow complex limestone and mixed coral habitats. The species is widespread in the region, found in Florida, the S. Gulf of Mexico, the Bahamas, and across the Caribbean Sea except NE Venezuela. Unfortunately, the 19, 20, and 21-spined Labrisomus are very similar morphologically and are frequently confused in guidebooks and photographs. All six species share the blunt-headed and goggle-eyed appearance, at least as juveniles, i.e. the snout length (bony orbit to jaw tip) is less than two-thirds of the orbit diameter. Adult mimic blennies are recognized in the field mostly by a distinct opercular ocellus, well-outlined and typically with an orange posterior rim, and a relatively short first dorsal-fin spine. Juveniles are particularly difficult to separate, since the distinguishing markings for each species are either not well-developed or shared by other species at this early stage (but see description below). L. guppyi larvae are uncommon in collections.

Description:
Pre-transitional larvae: Body long, narrow, and thin with a medium eye, pointed snout, and terminal medium-sized mouth. Larvae can have the normal body shape or develop a hunched-over appearance (tip of snout below the lateral midline of the body). Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like; the third pelvic-fin ray is about 3/4 the length of the second. There are some small spines along the rim of the preoperculum that no longer project as larvae approach transition. The complement of melanophores on the top of the head is usually a narrow-U, i.e. a row of three on each side of the head with the spots closer to the dorsal midline anteriorly, plus a near-surface melanophore at the midline behind the mid-brain lobes (not the deep nuchal midline melanophore), completing a narrow-O (note that the rear side-by-side pair are typically more widely spaced than the middle pair). Usually there are additional equally large melanophores over some or all four quadrants, i.e. each lobe of the fore- and mid-brain. On more marked larvae, there is a prominent melanophore on each side just behind the tip of the upper jaw (this pair is often absent on lightly marked larvae). There is a cheek melanophore on each side. Melanophores typically run along the base of all of the soft dorsal-fin rays, and, on more heavily marked larvae, along some of the posterior dorsal-fin spines as well; however some lightly-marked larvae have only a few soft-dorsal fin base spots or even rarely none. A vertical line of melanophores develops along the base of the caudal-fin segmented rays (first proximal, then distal), sometimes few and mostly on the upper half, or rarely none, on lightly marked larvae. Some larvae can have one or two linear melanophore streaks outlining the mid-length of one or two lower caudal-fin segmented rays (most have none). Along the ventral midline there are melanophores at the isthmus and deep behind the pelvic-fin base. There is no extensive speckling of the peritoneum visible through the ventral abdominal wall, but some more heavily marked larvae can show some peritoneal speckling on the upper sidewalls of the abdomen. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, followed by none to three along the ventral midline of the caudal peduncle. A row of internal melanophores overlies the vertebral column, spaced about every third vertebra, along the mid- and rear body, continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. guppyi larvae in transition develop metamorphic melanophores over the head and body simultaneously, a mostly uniformly speckling of fine melanophores, although some transitional larvae develop an indistinct pattern of dark bars.The full complement of larval melanophores, especially multiple spots over each quadrant of the forebrain and midbrain as well as the pair behind the tip of the upper jaw are present at transition.

Juveniles: L. guppyi juveniles have dark bars on the body that extend onto the dorsal-fin membranes, with the second body bar (under the 10-15th dorsal-fin spines) covering the bases of about 4 spines. The last dark bar on the tail ends as a straight vertical line or a slight crescent. Early juveniles may have only a diffuse dark spot on the operculum, but they rapidly develop an ocellus with a thin orange rim on the posterior edge. The first dorsal-fin spine is notably short, only a third or less of the body depth at the dorsal-fin origin and well shorter than the mid-fin spines.

Analogues:
The larvae of the 19-spined Labrisomus are likely identical, although, as they approach transition, L. guppyi larvae should develop their shorter first dorsal-fin spine.

Lightly-marked larvae of L. guppyi missing the pair of melanophores behind the tip of the upper jaw can be distinguished from larvae of L. nuchipinnis, L. conditus, and L. cricota, by the absence of melanophores along the base of the anterior half of the spinous dorsal fin, especially the first ten spines, and the absence of melanophores outlining the lower segmented rays of the caudal fin (also many of the latter three species have only a single melanophore over the forebrain quadrants (V of 5) vs. more on L. guppyi). L. albigenys and L. nigricinctus larvae are very lightly-marked, missing most of the melanophore complement of L. guppyi. Among the Malacoctenus larvae, only M. aurolineatus and a rare M. triangulatus share the melanophores along the base of the soft dorsal fin; the former have a distinctive head melanophore pattern and the latter are distinguished by a short third pelvic-fin ray, many head melanophores varying from tiny to large, and a dorsal-fin outline with a short third-to-last spine. Other Malacoctenus larvae may resemble the rare L. guppyi without dorsal midline melanophores, but they all have fewer head melanophores not in the U or O pattern and/or dorsal-fin outlines with short posterior spines and often different fin-ray counts.

L. guppyi larvae with the pair of melanophores behind the tip of the upper jaw can be distinguished from L. bucciferus larvae by a shorter first dorsal-fin spine (as they approach transition) and usually one fewer dorsal-fin spine (possibly also by additional small head melanophores, if present, over all quadrants vs. only forebrain). L. haitiensis larvae differ in having abdominal speckling, melanophores at the base of dorsal-fin spines 8 or 9, longer pelvic fins with a short third ray, and additional dorsal-fin spines.

Transitional L. guppyi larvae are distinguished by fin-ray counts, persistent larval melanophores, and their uniform speckling of metamorphic melanophores. The pair of melanophores behind the tip of the upper jaw is shared only by the other 19- and 20+-spined species, L. gobio, L. kalisherae, L. bucciferus, and L. haitiensis, all of which have a different dorsal-fin outline, with longer first spines (about two to 2.5 times in the body depth at the dorsal-fin origin vs. 3 times or more, and about the same length as the the mid-fin spines vs. well shorter). Transitional L. haitiensis develop a prominent pattern of ovals and bars. The transitional larvae of L. nuchipinnis, L. conditus, and L. cricota develop reticulated lines over the body (vs. uniform speckling). Transitional L. guppyi larvae are separated from transitional Malacoctenus larvae by the uniform markings over the head and body (developing at the same time), short cirri, and the dorsal-fin outline.

The juveniles of the 19- and 20-spined Labrisomus are blunt-headed, compared to the 18-spined Labrisomus (other than L. albigenys), i.e. the snout length (bony orbital margin to the tip of the closed jaw) is less than two-thirds the bony orbit diameter. Small juveniles of the blunt-headed Labrisomus are difficult to identify to species, especially since some species described with opercular ocelli can have only a diffuse dark spot on the operculum when young. In addition, those species described without ocelli can often have an outlined dark spot on the operculum (but not a thin-rimmed ocellus) as juveniles.

Juvenile L. guppyi who have not yet developed a distinct opercular ocellus are difficult to separate from L. gobio juveniles: the key differences are a shorter first dorsal-fin spine (about a third the body depth at the dorsal-fin origin and well shorter than the mid-fin spines vs. about half and slightly shorter, about 90%), the dark bars on the body extend onto the fins in L. guppyi (vs. not onto the fins) and the mid-body bar covers about 3 or 4 spine bases (vs. widening to reach 5 or 6). Juvenile L. kalisherae, as well as L. bucciferus and L. haitiensis (both with higher fin-ray counts), are separated from L. guppyi by having distinctly longer first dorsal-fin spines (about two into the body depth and the same length or a little shorter than the mid-fin spines vs. well shorter) and the pigment on the caudal peduncle ending by outlining three light spots vs. a mostly straight vertical line in both L. guppyi and L. gobio. Juvenile L. albigenys share the dorsal-fin outline of L. guppyi (relatively short first and penultimate dorsal-fin spines) and are best distinguished by the absence of an opercular spot or ocellus and their lower fin-ray counts. After juvenile L. guppyi develop an opercular ocellus with a thin rim (at least on the posterior edge), they can be distinguished from other ocellated species: from L. nigricinctus and L. nuchipinnis (as well as L. conditus and L. cricota, both with less distinct ocelli) by the blunt snout and from L. haitiensis (which can have a similar opercular spot) and L. filamentosus by the short first dorsal-fin spine (and from all by fin-ray counts).

Diagnosis: The modal fin-ray count of D-XIX,11 A-II,19 and P-13 is shared by the 19-spined trio of L. kalisherae, L. gobio, and L. guppyi, as well as by Malacoctenus aurolineatus (but usually with 14 pectoral-fin rays). Note that almost 90% of L. kalisherae individuals have 19 dorsal-fin spines. The fin-ray count falls within the upper or lower range for most other Labrisomus species and both M. delalandii and M. gilli. (DNA)

Ecology:
The downy blenny is an uncommon small blenny found mostly in inshore shallow habitats, particularly associated with algae and rubble. The species ranges from Florida and the S. Gulf of Mexico along the continental coast and across the Southern Caribbean to NE Venezuela (where it is the only 19- or 20-spined Labrisomus species), Noronha, and mainland Brazil. However, it is common only in cooler and/or turbid-water areas such as the inshore reefs of Belize and Florida, Venezuela, and Brazil. It appears to be replaced by L. bucciferus in warmer clear-water areas such as the Bahamas, the Antilles, and the offshore barrier reef and atolls in Belize. Unfortunately, the 19, 20, and 21-spined Labrisomus are very similar morphologically and are frequently confused in guidebooks and photographs. All six species share the blunt-headed and goggle-eyed appearance, at least as juveniles, i.e. the snout length (bony orbit to jaw tip) is less than two-thirds of the orbit diameter. Adult downy blennies are recognized in the field mostly by the absence of an opercular ocellus, intensely spotted fins, especially the anal fin, relatively long first two dorsal-fin spines (and, on close inspection, only two submandibular pores). Juveniles are particularly difficult to separate, since the distinguishing markings for each species are either not well-developed or shared by other species at this early stage (but see description below). L. kalisherae larvae are unknown or unrecognized in collections.

Description:
(pre-transitional larvae have not been identified, but are likely identical among the 19-spined Labrisomus, see L. guppyi)

Transitional stage: Transitional L. kalisherae larvae have not been identified.

Juveniles: L. kalisherae juveniles have dark bars on the body that extend onto the fins. The last dark bar ends on the caudal-fin base outlining three light spots. Although there can be a dark spot on the operculum, it is not an ocellus with a thin rim. The ventral and pectoral fins have dark spotting, with 5 or 6 distinct dark bands along the pelvic fin-rays. The first dorsal-fin spine is relatively long, about half the body depth at the dorsal-fin origin, and similar in length or slightly shorter than the mid-fin spines.

Analogues:
Transitional L. kalisherae larvae likely differ from the other 19-spined Labrisomus only by the length of the first dorsal-fin spine, which should be relatively long, not distinctly shorter than the fourth to sixth spines.

The juveniles of the 19- and 20-spined Labrisomus are blunt-headed, compared to the 18-spined Labrisomus (other than L. albigenys), i.e. the snout length (bony orbital margin to the tip of the closed jaw) is less than two-thirds the bony orbit diameter. Small juveniles of the blunt-headed Labrisomus are difficult to identify to species, especially since some species described with opercular ocelli can have only a diffuse dark spot on the operculum when young. In addition, those species described without ocelli can often have an outlined dark spot on the operculum (but not a thin-rimmed ocellus) as juveniles.

L. kalisherae are almost identical to L. bucciferus by appearance, although fortunately the latter typically have 20 dorsal-fin spines. The adult character of the number of pores at the submandibular symphysis does not apply to juveniles. The marking differences are quite subtle, with L. kalisherae having more spotted ventral and pectoral fins, especially more dark bands along the pelvic fin-rays (5 to 7 vs. 4) and L. bucciferus are more likely to show short dark lines radiating from the rear orbital rim and numerous small pale spots over the operculum. Juvenile L. kalisherae are best separated from L. gobio and L. guppyi by having the pigment on the caudal-fin base outlining three light spots (vs. ending as a mostly straight vertical line) and by having distinctly longer first two dorsal-fin spines (vs. L. guppyi, i.e. about half the body depth at the dorsal-fin origin and longer than or equal to the 4th), often with membranes opacified with white or colors (vs. both species). In addition, L. gobio differs in having the dark bars on the body not extending onto the fins and L. guppyi rapidly develops an opercular ocellus. Juvenile L. haitiensis (and L. bucciferus) share the relatively long first dorsal-fin spines (often with white-shaded membranes) with L. kalisherae, but L. haitiensis have longer pelvic fins (reaching past the anal-fin origin) with an inconspicuous short third pelvic-fin ray, often a dark opercular spot, and higher fin-ray counts. L. albigenys are best distinguished by their short first dorsal-fin spine and lower fin-ray counts. The remaining Labrisomus juveniles are distinguished by their opercular ocelli, longer snouts, and fin-ray counts i.e. L. nigricinctus and L. nuchipinnis (as well as L. conditus and L. cricota, both with less distinct ocelli), and L. filamentosus (blunt-snouted but with longer first dorsal-fin spines).

Diagnosis: The modal fin-ray count of D-XX,11 A-II,20 and P-13 indicates Labrisomus bucciferus, as well as some chaenopsids of Emblemariopsis. Note that almost 90% of L. bucciferus individuals have 20 dorsal-fin spines. This fin-ray count falls within the upper range for L. gobio and L. kalisherae and the lower range for L. haitiensis (usually with 14 pectoral-fin rays), and overlaps the range for Malacoctenus delalandii, M. gilli, M aurolineatus, and M. triangulatus. (DNA)

Ecology:
The puffcheek blenny is a common small blenny found mostly in shallow rocky, seagrass, and mixed coral habitats. The species is widespread in the region, found in Florida, the Dry Tortugas in the Gulf of Mexico, Bermuda, the Bahamas, and across the Caribbean Sea except NE Venezuela. However, they are common only in warmer and clear-water areas such as the Bahamas, the Antilles, and the offshore barrier reef and atolls in Belize and notably uncommon in Florida and absent from most of the Gulf of Mexico and Venezuela. It appears to be replaced by L. kalisherae in cooler and/or turbid-water areas such as Florida and Venezuela and the inshore reefs of Belize. Unfortunately, the 19, 20, and 21-spined Labrisomus are very similar morphologically and are frequently confused in guidebooks and photographs. All six species share the blunt-headed and goggle-eyed appearance, at least as juveniles, i.e. the snout length (bony orbit to jaw tip) is less than two-thirds of the orbit diameter. Adult puffcheek blennies are recognized in the field mostly by the lack of an opercular spot or ocellus, dark lines behind the eye and pale spotting over the operculum, and relatively long first two dorsal-fin spines. Juveniles are particularly difficult to separate, since the distinguishing markings for each species are either not well-developed or shared by other species at this early stage (but see description below). L. bucciferus larvae are occasional in collections.

Description:
(pre-transitional larvae have not been identified, but the description is based on the transitional larvae; lightly marked larvae may be missing some of the melanophore complement)
Pre-transitional larvae: Body long, narrow, and thin with a medium eye, pointed snout, and terminal medium-sized mouth. Larvae can have the normal body shape or develop a hunched-over appearance (tip of snout below the lateral midline of the body). Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like; the third pelvic-fin ray is about 3/4 the length of the second. There are some small spines along the rim of the preoperculum that no longer project as larvae approach transition. The full complement of large melanophores on the top of the head typically consists of a row of three on each side of the head, usually in a narrow-U, i.e. the spots get closer to the dorsal midline anteriorly, usually with one to a few additional spots over the forebrain lobes (note that the rear side-by-side pair are often more widely spaced than the middle pair). There is a prominent melanophore on each side just behind the tip of the upper jaw. There is a cheek melanophore on each side. Melanophores run along the base of all of the soft dorsal-fin rays as well as some of the posterior dorsal-fin spines. A vertical line of melanophores develops along the base of the caudal-fin segmented rays curving around to the base of the larger procurrent rays. Along the ventral midline there are melanophores at the isthmus and deep behind the pelvic-fin base. There is no extensive speckling of the peritoneum visible through the ventral abdominal wall, but some more heavily marked larvae can show some peritoneal speckling on the upper sidewalls of the abdomen. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, followed by none to three along the ventral midline of the caudal peduncle. A row of internal melanophores overlies the vertebral column, spaced about every third vertebra, along the mid- and rear body, continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. bucciferus larvae in transition develop metamorphic melanophores over the head and body simultaneously. The head and body are mostly uniformly speckled with fine melanophores, although some transitional larvae develop an indistinct pattern of dark bars.

Juveniles: L. bucciferus juveniles have dark bars on the body that extend onto the fins. The last dark bar ends on the caudal-fin base outlining three light spots. There is usually no dark spot or ocellus on the operculum, which is typically covered with small pale spots. The dark lines radiating from the rear orbit are usually prominent. The anal and pectoral fins have a few dark bands, but are not heavily spotted, and the pelvic fin-rays usually have 3-4 dark bands. The first two dorsal-fin spines become long, more than half the body depth at the dorsal-fin origin, and equal or longer then the mid-fin spines.

Analogues:
Based on the transitional stage, pretransitional L. bucciferus larvae share the pair of melanophores behind the tip of the upper jaw with the 19-spined species and L. haitiensis. Unlike those species, the extra melanophores in addition to the basic U or O head spot pattern may be limited to the forebrain lobes vs. over all quadrants (it remains to be confirmed if this pattern is consistent). Otherwise, they share melanophore patterns with the 19-spined species and the (usually) extra dorsal-fin spine may then be the only distinction from L. gobio and L. kalisherae (L. guppyi should have a shorter first dorsal-fin spine). L. haitiensis larvae usually differ in having abdominal speckling, melanophores at the base of dorsal-fin spines 8 or 9, and longer pelvic fins with a short third ray.

The larvae of the chaenopsid blennies of Emblemariopsis can be distinguished by having a gap between the 3rd and fourth dorsal-fin spines, only 3 procurrent caudal-fin rays (vs. 6 or more), a slimmer body shape, and many fewer melanophores.

Transitional L. bucciferus larvae are distinguished by fin-ray counts, persistent larval melanophores, and their uniform speckling of metamorphic melanophores. The pair of melanophores behind the tip of the upper jaw is shared only by the 19-spined species (L. gobio, L. guppyi, and L. kalisherae) and L. haitiensis. The transitional larvae of L. gobio and L. kalisherae have not been identified, but likely can only be distinguished by the fin-ray count. Transitional L. haitiensis as well as L. nuchipinnis, L. conditus, and L. cricota develop reticulated patterns over the body (vs. uniform speckling). The dorsal-fin outline separates transitional L. bucciferus from many congeners: the first spine is relatively long, about two to 2.5 times in the body depth at the dorsal-fin origin, and about the same length as the the mid-fin spines (vs. distinctly shorter, 3 times or more into body depth, in L. nuchipinnis, L. conditus, L. albigenys, L. nigricinctus, and L. guppyi, and well shorter than the mid-fin spines in the latter three species). Transitional L. bucciferus larvae are separated from transitional Malacoctenus larvae by the uniform markings over the head and body (developing at the same time), short cirri, and the dorsal-fin outline.

The juveniles of the 19- and 20-spined Labrisomus are blunt-headed, compared to the 18-spined Labrisomus (other than L. albigenys), i.e. the snout length (bony orbital margin to the tip of the closed jaw) is less than two-thirds the bony orbit diameter. Small juveniles of the blunt-headed Labrisomus are difficult to identify to species, especially since some species described with opercular ocelli can have only a diffuse dark spot on the operculum when young. In addition, those species described without ocelli can often have an outlined dark spot on the operculum (but not a thin-rimmed ocellus) as juveniles.

Juvenile L. bucciferus are difficult to separate from L. kalisherae by appearance, although fortunately L. kalisherae typically have only 19 dorsal-fin spines. The adult character of the number of pores at the submandibular symphysis does not apply to juveniles. The marking differences are quite subtle, with L. bucciferus having less spotted ventral and pectoral fins and fewer dark bands along the pelvic fin-rays (3 or 4 vs. 5 or 6), and more likely to show short dark lines radiating from the rear orbital rim and numerous small pale spots over the operculum. Juvenile L. haitiensis (and L. kalisherae) share the relatively long first dorsal-fin spines (often with white-shaded membranes) with L. bucciferus, but L. haitiensis have distinctly longer pelvic fins (reaching past the anal-fin origin and with 6-7 bands) with a short and inconspicuous third pelvic-fin ray, and often a dark opercular spot. Juvenile L. bucciferus are best separated from L. gobio and L. guppyi by having the pigment on the caudal-fin base outlining three light spots (vs. ending as a mostly straight vertical line) and higher fin-ray counts. In addition, L. gobio differ in having the dark bars on the body not extending onto the fins and L. guppyi have a much shorter first dorsal-fin spine (less than a third of the body depth at the dorsal-fin origin vs. half or more) and rapidly develop an opercular ocellus. L. albigenys are best distinguished by their short first dorsal-fin spine and lower fin-ray counts. The remaining Labrisomus juveniles are distinguished by their opercular ocelli, longer snouts, and fin-ray counts i.e. L. nigricinctus and L. nuchipinnis (as well as L. conditus and L. cricota, both with less distinct ocelli), and L. filamentosus (blunt-snouted but with longer first dorsal-fin spines).

Diagnosis: The modal fin-ray count of D-XXI,11 A-II,21 and P-14 indicates Labrisomus haitiensis. This fin-ray count falls within the range for Malacoctenus aurolineatus, M. triangulatus, M. boehlkei, and M. macropus. (DNA)

Ecology:
The reef blenny is a somewhat common small blenny found mostly on well-developed coral reefs at moderate depths. The species is found in Florida, the Bahamas, the S. Gulf of Mexico, and across the Caribbean Sea except NE Venezuela. Unfortunately, the 19, 20, and 21-spined Labrisomus are very similar morphologically and are frequently confused in guidebooks and photographs. All six species share the blunt-headed and goggle-eyed appearance, at least as juveniles, i.e. the snout length (bony orbit to jaw tip) is less than two-thirds of the orbit diameter. Adult reef blennies are recognized in the field mostly by a longer pelvic fin, reaching the anal-fin origin (when straightened) and with an inconspicuous short third ray, as well as relatively long first two dorsal-fin spines (and, on close inspection, 21 dorsal-fin spines and 14 pectoral-fin rays). Although they are often described as having an unmarked operculum, many have a prominent opercular spot, sometimes even outlined as an ocellus. Juveniles can be difficult to identify, since the distinguishing markings for each species are either not well-developed or shared by other species at this early stage (but see description below). L. haitiensis larvae are occasional in collections.

Description:
Pre-transitional larvae: Body long, narrow, and thin with a large eye, pointed snout, and terminal medium-sized mouth. Long continuous dorsal and anal fins with a short and narrow caudal peduncle. Pectoral fins long, reaching past the vent, and pelvic fins long and thread-like, reaching more than two-thirds the way to the anal-fin origin; notably the third pelvic-fin ray is well less than half the length of the second. The typical complement of large melanophores on the top of the head consists of a row of three on each side of the head, usually in two crescents forming a wide-U, i.e. the middle side-by-side pair are often more widely spaced than the rear pair. Sometimes there is an additional near-surface melanophore at the midline behind the mid-brain lobes, completing a wide-O (not the deep nuchal midline melanophore). Some larvae develop one or a few additional smaller melanophores and an uncommon "peppered head" variant has numerous additional small melanophores over the mid-brain lobes. All larvae have a pair of melanophores behind the tip of the upper jaw, located adjacent to the base of the ascending process of the premaxilla on each side. Some larvae develop additional small melanophores around the pair. There is a cheek melanophore on each side. Melanophores run along the base of all of the soft dorsal-fin rays and some of the dorsal-fin spines, usually including spines 8 or 9 and 10, then 13-15, and then 17 rearward, but often all spines after the 8th, and occasionally only starting at the last two spines. A vertical line of melanophores develops along the base of the caudal-fin segmented rays curving around to the base of the larger procurrent rays. Rare individuals have thin linear melanophores outlining the length of the upper three and lower three caudal-fin segmented rays. Along the ventral midline there are melanophores at the isthmus and deep behind the pelvic-fin base. There is usually extensive speckling of the peritoneum visible both through the lateral abdominal wall as well as along the ventral abdominal aspect. Along the anal fin there is a melanophore at the base of each anal-fin soft ray, followed by one, sometimes none or two, along the ventral midline of the caudal peduncle. A row of internal melanophores overlies the vertebral column along the mid- and rear body, spaced about every third vertebra, usually continuing onto the caudal peduncle. Additional internal melanophores include those at the nuchal midline, otic capsule, and overlying the abdominal organs.

Transitional stage: L. haitiensis larvae develop metamorphic melanophores in a distinctive pattern of isolated loops and rings with vertical extensions. As transition progresses most of the larval melanophores on top of the head disappear and often only a few fragments are apparent.

Juveniles: L. haitiensis juveniles have dark bars on the body that extend onto the fins. The last dark bar ends on the caudal-fin base outlining three light spots. There can be a dark spot, often with white edging (but not an obvious complete ocellus), on the operculum. L. haitiensis have long pelvic fins, usually reaching past the anal-fin origin, with a distinctively short and inconspicuous third pelvic-fin ray (well less than half the length of the second).

Analogues:
There is some overlap between the melanophore patterns of larval L. haitiensis and the 19-spined species and L. bucciferus; however, L. haitiensis larvae apparently always have the combination of the pair behind the tip of the upper jaw, many along the base of the dorsal-fin spines (usually including spine 8, 9, or 10), and a well-speckled ventral abdominal wall. These are typically all present along with a minimal head complement of the simple U or O. In those other species, one or more of the combination is typically missing, especially when the head pattern is limited to a U or O. In addition, L. haitiensis larvae tend to have a wide-U or O with the middle pair of melanophores more widely-spaced than the rear pair, vs. a narrowing-U or O in the other Labrisomus. Morphology is generally required for a definitive separation: L. haitiensis larvae consistently have long pelvic fins, more than two-thirds the distance to the vent, with a short third ray (always less than half the next ray). Separation from the 18-spined species is easier: L. nuchipinnis, L. conditus, and L. cricota larvae apparently never have the pair of spots behind the tip of the upper jaw or more than two or three abdominal speckles (usually they have none visible), and consistently have melanophores on the inner cleithrum in the gill cavity as well as outlining the lower caudal-fin segmented rays (the latter rare on L. haitiensis larvae). In addition, those three species also have a narrowing-U, or often even a V-pattern of head melanophores (not seen on L. haitiensis larvae), and a different arrangement of spinous dorsal-fin base melanophores (8,11-12,14+). L. albigenys and L. nigricinctus larvae are very lightly-marked, missing most of the melanophores characteristic of L. haitiensis.

Among the Malacoctenus, only M. triangulatus can occasionally have larvae with melanophores along the base of the spinous dorsal fin and they share the long pelvic fins with a short third ray and even sometimes overlap in fin-ray counts with L. haitiensis. They can also have the basic head pattern of two crescents of three large melanophores per side but have additional melanophores over all fore- and mid-brain quadrants varying from tiny to large, usually ten per side or more. The "peppered head" variant of L. haitiensis larvae can resemble that pattern, but have most or all of the additional melanophores limited to the midbrain lobes. M. triangulatus can be distinguished further by the lack of ventral abdominal speckling and the absence of the pair of melanophores behind the tip of the premaxilla, located adjacent to the base of the ascending process, that is characteristic of some Labrisomus; note that the rare M. triangulatus variant (likely in transition) can have a cluster of small melanophores in that area and a pair on the ethmoids a very short distance away. In that case, the dorsal-fin outline (with a notably short third-to-last spine) and long cirri separate M. triangulatus. Lastly, the row of internal melanophores overlying the vertebral column is spaced at one for each vertebra in M. triangulatus vs. every third vertebra in Labrisomus.

Transitional L. haitiensis larvae are distinguished by fin-ray counts, persistent larval melanophores (although these disappear rapidly in this species), and the distinct pattern of metamorphic melanophores on the body. The pair of melanophores behind the tip of the upper jaw is shared only by the 19- and 20-spined species, L. gobio, L. guppyi, L. kalisherae, and L. bucciferus, all of which develop a uniform speckling of metamorphic melanophores on the body. The transitional larvae of L. nuchipinnis, L. conditus, and L. cricota develop connected reticulated lines over the body instead of the isolated loops and rings on L. haitiensis. Transitional M. triangulatus larvae have a generally similar appearance, but their melanophore pattern is inverted triangles, widest at the base of the dorsal-fin elements. Transitional M. versicolor larvae have a very similar transitional pattern of isolated bars and shapes, but have long third pelvic-fin rays (about 3/4 the length of the longest ray), no pair of spots at the tip of the jaw, notably long cirri, and very different fin ray counts.

The juveniles of the 19- and 20-spined Labrisomus are blunt-headed, compared to the 18-spined Labrisomus (other than L. albigenys), i.e. the snout length (bony orbital margin to the tip of the closed jaw) is less than two-thirds the bony orbit diameter. Small juveniles of the blunt-headed Labrisomus are difficult to identify to species, especially since some species described with opercular ocelli can have only a diffuse dark spot on the operculum when young. In addition, those species described without ocelli can often have an outlined dark spot on the operculum (but not a thin-rimmed ocellus) as juveniles.

Juvenile L. haitiensis have long pelvic-fins with a short third ray that separate them from all congeners (except L. filamentosus) and also have high fin-ray counts that rarely overlap with other Labrisomus species. Juvenile L. filamentosus have not been identified, but, since juvenile L. haitiensis can also have an ocellus-like spot on the operculum, it is possible that L. filamentosus may only be separated by fin-ray counts: an extra dorsal soft-fin ray (dorsal elements of 33) and 13 pectoral-fin rays (vs. 14). The marking differences for juvenile L. haitiensis are subtle, with L. bucciferus and L. kalisherae sharing the relatively long first dorsal-fin spines (often with white-shaded membranes) and the pigment on the caudal-fin base outlining three light spots (vs. ending as a mostly straight vertical line in L. gobio and L. guppyi). In addition, L. bucciferus have fewer dark bands along the pelvic fin-rays (4 vs. 6 or 7), L. gobio differ in having the dark bars on the body not extending onto the fins, and L. guppyi rapidly develop a thin-rimmed opercular ocellus and have a much shorter first dorsal-fin spine (less than a third of the body depth at the dorsal-fin origin vs. half or more). L. albigenys differ by having a very short first dorsal-fin spine and lower fin-ray counts. The remaining Labrisomus juveniles are distinguished by their longer snouts and lower fin-ray counts i.e. L. nigricinctus and L. nuchipinnis (with well-delineated ocelli), as well as L. conditus and L. cricota.