Labrisomidae, the scaled blennies in the Guide to the larval reef fishes of the Caribbean: labrisomid coral reef fish larvae

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family Tripterygiidae

The labrisomids, or scaled blennies, are generally small and nondescript fishes, yet they can be quite common on and around Caribbean reefs. They comprise one of the largest families of reef fishes in the region, with over 40 species. Labrisomid genera tend to be quite speciose and species-level identifications are generally difficult. Fortunately almost all of the species belong to only four large genera, making identifications to genus rather simple. Two of the genera, Starksia spp. and Paraclinus spp., contain numerous similar-appearing species that are typically tiny and cryptic. The more conspicuous genera in this family are Malacoctenus spp. with eight Caribbean species and Labrisomus spp. with nine. The remaining regional labrisomids are two obscure deep-water genera that are monotypic: Nemaclinus atelestos and Haptoclinus apectolophus.

Labrisomid larvae can be recognized by their their pointed snout, long and continuous dorsal and anal fins with flexible spines, a very short and narrow caudal peduncle, long strand-like pelvic fins (usually straight, not curled up over the body), the absence of spines on the head, and light markings (basically a row of melanophores along the anal fin base and often a few on top of the head). Larval labrisomids have large round eyes, in contrast to the early life history stages of many labrids, scarids, and gobies, in which the eye can be smaller or narrowed.

Some of the closely-related chaenopsids are quite similar in general appearance to larval labrisomids, but chaenopsids usually have more than 13 dorsal fin soft rays and 34 or more total dorsal fin elements, while regional labrisomids always have 13 or fewer dorsal fin soft rays and fewer than 34 total dorsal fin elements. The Caribbean chaenopsids that share the low dorsal fin soft ray count with labrisomids are Coralliozetus cardonae, Emblemaria vitta, Acanthemblemaria johnsoni (Tobago only?), A. rivasi (from the SW Caribbean) and the Emblemariopsis spp. The genus Stathmonotus is still considered chaenopsid even though their dorsal fin is made up of all spines.

Labrisomids can be separated easily from blenniids, since the blenniids have fewer dorsal fin spines than soft rays and blunt snouts at all stages. Tripterygiids have three separated dorsal fins and dactyloscopids have curled pelvic fins. Many larval gobies fit the general labrisomid gestalt, but have separate and very short spinous dorsal fins with spindly spines, and often a pelvic fin disk as well.

Malacoctenus spp. vs. Labrisomus spp.

There are two conspicuous labrisomid genera on Caribbean reefs: the Malacoctenus spp. and the Labrisomus spp. Both genera contain species that are typically seen out in the open and can be very common. Malacoctenus spp. are relatively small, usually an inch or two, while Labrisomus spp. are larger and bulkier (some can even reach six inches). These two groups can be distinguished from their tiny and cryptic relatives, the Starksia spp. and the Paraclinus spp. by fin ray counts: the former has fewer second dorsal fin rays and pectoral fin rays (with a few exceptions) and the latter have all (or all but one) dorsal fin elements spinous.

The two genera have overlapping fin ray counts and are hard to separate on that basis alone. One major difference is the shape of the snout, pointed in Malacoctenus spp., blunted in Labrisomus spp. (except for very pointed in L. nigricinctus), but it is unclear whether this feature is consistent enough in early life history stages. Another basic difference is that the rear edge of the maxilla is sheathed in Malacoctenus spp. and exposed in Labrisomus spp. and the mouth is small and extends back only to the level of the anterior orbit in Malacoctenus spp. (and L. nigricinctus) and large and extending back past the level of the pupil in Labrisomus spp. Similarly, however, this character is unlikely to be useful in earlier stages. Lastly, in Malacoctenus spp. (and L. nigricinctus) the shortest dorsal fin spine is often many times shorter than the longest dorsal fin ray, while in Labrisomus spp. the shortest dorsal fin spine is typically about half the length of the longest dorsal fin ray. The usefulness of these distinctions for larvae awaits further series of specimens.

Fin ray counts can be very useful in this group, especially since the ranges of counts is documented. They are listed here in order of increasing fin ray counts (the range with the known combinations follow in parentheses).

mostly from Springer's monograph "Systematics and Zoogeography of the Clinid Fishes of the Subtribe Labrisomini Hubbs"

Malacoctenus spp.

M. versicolor: mode D-XVIII,12 __A-II,18-19 Pect 14 (rarely 11 dorsal fin soft rays; pect 13-14)

M. delalandei : mode D-XX,10 __A-II,19 Pect 14 (dorsal 19/9-11 and 20/9-11 and 21/9; anal 17-20; pect 13-15)

M. gilli: mode D-XX,10 __A-II,19 Pect 14 (dorsal 18/10 and 19/10-11 and 20/9-11 and 21/9-10; anal 17-21; pect 13-16)

M. aurolineatus: mode D-XIX-XX,11 __A-II,19-20 Pect 14 (dorsal 18/10-11 and 19/10-12 and 20/10-12 and 21/10-11; anal 17-21; pect 13-15)

M. triangulatus: mode D-XX,12 __A-II,21 Pect 14 (dorsal 19/12-13 and 20/11-13 and 21/11; anal 20-22; pect 13-15)

M. boehlkei: D-XX,13 or XXI, 11-12 or XXII,11 __A-II,22 (range 20-23) Pect 15

M. erdmani: D-XXI,9 __A-II,18-19 Pect 16 (dorsal 20/9-10 and 21/8-10 and 22/8-9; anal 17-20; pect 15-17)

M. macropus: D-XXI,9-11 or XXII,8-10 or XXIII,9-10 __A-II,20-21 (range 18-22) Pect 15 (range 14-16)

Labrisomus spp.

eighteen dorsal fin spine group

L. albigenys: mode D-XVIII,11 A-II,18 Pect 13

L. nigricinctus: mode D-XVIII,11 A-II,18 Pect 13 (dorsal 17/11 and 18/10-12 and 19/11; anal 17-20)

L. nuchipinnis: mode D-XVIII,12 A-II,18-19 Pect 14 (dorsal 17/12-13 and 18/10-13 and 19/11-12 and 20/12; anal 17-19; pect 13-15)

(note: the chaenopsid Emblemaria vitta overlaps the fin ray count of L. nuchipinnis)

nineteen dorsal fin spine group

L. gobio: mode D-XIX,11 A-II,19 Pect 13 (dorsal 18/12 and 19/10-12; anal 18-20; pect 12-13)

L. guppyi: mode D-XIX,11 A-II,19 Pect 13 (dorsal 18/11-12 and 19/10-12; anal 18-20; pect 12-14)

L. kalisherae: mode D-XIX,11 A-II,19 Pect 13 (dorsal 18/11-12 and 19/10-12 and 20/10-11; anal 18-20; pect 13-14)

twenty plus dorsal fin spine group

L. bucciferus: mode D-XX,11 A-II,20 Pect 13 (dorsal 19/11-12 and 20/10-12 and 21/10; anal 19-21; pect 12-14)

L. haitiensis: mode D-XX-XXI,10-11 A-II,20-21 Pect 14 (dorsal 20/10-12 and 21/10-11 and 22/10-11; anal 18-22; pect 13-15)

L. filamentosus: mode D-XXI,12 A-II,21

note: the chaenopsids Emblemariopsis spp. overlap the fin ray counts of many of the labrisomids listed above and Coralliozetus cardonae overlaps some (D-XVIII,12 A-II-20 (dorsal 17-19/10-13; anal 18-24; pect 11-13)

Malacoctenus macropus

Diagnosis: Pointed snout profile at transition and modal fin ray counts of D-XXI,10 A-II,20 and Pect-15 indicate Malacoctenus macropus. The modal dorsal fin ray count is near the center of the range reported for M. macropus and M. erdmani. In addition, about 20% of individuals have 22 dorsal fin spines and fewer than 10 dorsal soft fin rays, which occurs only in M. macropus (and to a lesser extent in M. erdmani). Unfortunately fin ray counts overlap for M. macropus and M. erdmani, but the ranges do serve to separate the species. Many M. macropus have 21 anal fin soft rays, while M. erdmani has a maximum of 20 (mode of 18-19). Many M. macropus have 14 pectoral fin rays, while M. erdmani has a minimum of 15. The relative length of dorsal fin spines is an additional character separating these two species: the first dorsal fin spine is usually longer than the tenth and always longer than the last in M. macropus (vs. usually shorter than the tenth and the last in M. erdmani). However, since the range of fin ray counts for M. erdmani and M. macropus do overlap and it is not certain whether relative spine lengths are consistent for larvae, some individuals may require DNA sequence analysis to identify the species. Transitional recruit with bicolor pattern of dark above, light below indicates M. macropus. (ML)

Analogues:

Description: Body long, somewhat narrow and thin with a large eye, pointed snout, and terminal large mouth. Pectoral and pelvic fins long, reaching to or past the vent. Dorsal head melanophores consist of a pair (one per side) over the braincase, or often just one off-center. There is often one melanophore on the operculum at the level of the mid-eye. Along the ventral midline there are melanophores at the isthmus and the pelvic fin insertion (usually larger), then a large deep melanophore just behind the pelvic fin base. There are a row of melanophores along the base of the anal fin, one for each anal soft fin ray (not the two spines), continuing with a few smaller melanophores along the caudal peduncle ending at the start of the accessory caudal fin rays. Internal melanophores are present around the sacculus and the rear braincase, as well as a deep melanophore just behind the braincase. Then there are several melanophores spaced along the dorsal peritoneal cavity and sometimes a melanophore around the gut near the vent. Transitional larvae develop solid patches of tiny melanophores on the top of the head and in bars radiating from the eye (and on the iris); most prominently at about 8 o'clock on the eye and across the upper jaw, and then in patches below the eye, on the cheek, and at the base of the pectoral fin. Melanophores develop on the dorsal fin in patches at intervals along the forward half of the fin.

Malacoctenus macropus larva

10.0 mm SL

internal melanophore pattern

San Blas, Panama, SB86-409

Malacoctenus macropus transitional larva

11.3 mm SL

single head melanophore slightly off center
D-XXI,10 A-II,20 Pect-14

San Blas, Panama, SB86-604

Malacoctenus macropus
transitional recruit

11.4 mm SL

San Blas, Panama, SB83-103

Malacoctenus erdmani

Diagnosis: Pointed snout profile at transition and modal fin ray counts of D-XXI,9 A-II,18-19 and Pect-16 indicate Malacoctenus erdmani. This combination of fin ray counts is at the edge of the range reported for M. macropus (and extreme for M. gilli), but many individuals have only twenty dorsal fin spines (below Springer's reported range for M. macropus) and/or the combination of 18 anal fin rays and 16 pectoral fin rays (characteristic of M. erdmani, and rare for M. macropus; reported by Springer) and/or twenty-one dorsal fin spines with only 8 dorsal fin rays (only in M. erdmani). The relative length of dorsal fin spines is an additional character separating these two species: the first dorsal fin spine is usually shorter than the tenth and the last in M. erdmani (vs. usually longer than the tenth and always longer than the last in M. macropus). However, since the range of fin ray counts for M. erdmani and M. macropus do overlap and it is not certain whether relative spine lengths are consistent for larvae, this larval type could sometimes include individuals of M. macropus.

Analogues:

Description: Body long, somewhat narrow and thin with a large eye, pointed snout, and terminal large mouth. Pectoral and pelvic fins long, reaching to or past the vent. Dorsal head melanophores consist of a pair (one per side) over the braincase, or often just one off-center. There is often one melanophore on the operculum at the level of the mid-eye. Along the ventral midline there are melanophores at the anterior thorax and the pelvic fin insertion (usually larger), then a large deep melanophore just behind the pelvic fin base. There are a row of melanophores along the base of the anal fin, one for each anal soft fin ray (not the two spines), continuing with a few smaller melanophores along the caudal peduncle ending at the start of the accessory caudal fin rays. Internal melanophores are present around the sacculus and the rear braincase, as well as a deep melanophore just behind the braincase. Then there are several melanophores spaced along the dorsal peritoneal cavity and sometimes a melanophore around the gut near the vent.

Malacoctenus erdmani larva, 10.0 mm SL (San Blas, Panama, SB86-409)

Malacoctenus erdmani larva, 10.0 mm SL (relatively long tenth and last dorsal fin spine)(D-XXI,8 A-II,18 Pect-)(San Blas, Panama, SB87-223)

Malacoctenus triangulatus

Diagnosis: Pointed snout profile at transition and modal fin ray counts of D-XIX-XX, 11-12 A-II, 20-21 and Pect-14-15 indicate Malacoctenus spp. Individuals with twenty dorsal fin spines and twelve dorsal soft fin rays occur only in M. triangulatus and M. aurolineatus. A mode including 21 anal soft fin rays indicates M. triangulatus. Transitional recruit with dorsal fin spot at the base of the first three spines extending onto the body and inverted triangular markings along dorsal body indicates M. triangulatus. (ML)

Analogues:

Description: Body long, somewhat narrow and thin with a large eye, pointed snout, and terminal large mouth. Pectoral and pelvic fins long, reaching to or past the vent. Dorsal head melanophores consist of a pair (one per side) over the braincase, or often just one off-center. There is often one melanophore on the operculum at the level of the mid-eye. Along the ventral midline there are melanophores at the anterior thorax and the pelvic fin insertion (usually larger), then a large deep melanophore just behind the pelvic fin base. There are a row of melanophores along the base of the anal fin, one for each anal soft fin ray (not the two spines), continuing with a few smaller melanophores along the caudal peduncle ending at the start of the accessory caudal fin rays. Internal melanophores are present around the sacculus and the rear braincase, as well as a deep melanophore just behind the braincase. Then there are several melanophores spaced along the dorsal peritoneal cavity and sometimes a melanophore around the gut near the vent.

Malacoctenus triangulatus
transitional recruit

15.4 mm SL

San Blas, Panama, SB81-074

Malacoctenus triangulatus
transitional recruit

15.5 mm SL

San Blas, Panama, SB83-141

Malacoctenus aurolineatus ?

Diagnosis: Pointed snout profile at transition and a fin ray count of D-XX,11 A-II,20 and Pect-14 indicate Malacoctenus spp. M. aurolineatus has this modal fin ray count, but the fin ray counts also fall within the range for M. gilli, M delalandei, and M. triangulatus, which cannot be excluded. L. haitiensis described below also cannot be excluded from the type (especially if the pointed snout is present in Labrisomus spp. larvae before transition). C9 (ML)

Analogues:

Description: Body long, somewhat narrow and thin with a large eye, pointed snout, and terminal large mouth. Pectoral and pelvic fins long, almost reaching to vent. Dorsal head melanophores consist of one large central melanophore over the rear brain case and a smaller one midline above the eye. There are a few more tiny melanophores around the orbit rim, interorobital, and nasal bone and a few on the operculum. At the ventral midline there are two melanophores along the isthmus, the smaller one forward, and a large subsurface melanophore behind the pelvic fin base. There are a row of melanophores along the base of the anal fin, one for each anal soft fin ray, continuing with a few smaller melanophores along the caudal peduncle ending at the start of the accessory caudal fin rays. There are a few melanophores along the base of some of the dorsal soft fin rays as well as a thin bar of melanophores outlining the base of the caudal fin segmented rays and a scattering of tiny melanophores along the lower caudal fin segmented rays. A row of deep internal melanophores are present above the spinal column at the posterior end of the body.

Malacoctenus aurolineatus ? larva

12.3 mm SL

San Blas, Panama, SB86-429

Labrisomus haitiensis ?

Diagnosis: Modal fin counts of D-XX,11 A-II,20 and Pect-14 with a slightly blunted profile at transition indicates Labrisomus spp. L. haitiensis is the only species of the genus with a mode of XX dorsal fin spines and 14 pectoral fin rays. The fin ray count cannot exclude L. bucciferus, and may be within the extreme range for L. kalisherae (however the latter's range does not include 21 anal soft fin rays, present in this type). Malacoctenus aurolineatus shares the modal fin ray count, and M. gilli, M. delalandei, and M. triangulatus fall within the possible fin ray count range, but the head shape likely excludes these species. (PE) C9a

Analogues:

Description: Body long, somewhat narrow and thin with a large eye, slightly blunted profile at transition, and terminal large mouth. Pectoral and pelvic fins long, almost reaching to vent. Melanophores in a row along the base of the anal fin, one for each anal soft fin ray, continuing with six to eight more smaller melanophores along the caudal peduncle ending at the start of the accessory caudal fin rays. There are often a few melanophores along the base of some of the dorsal soft fin rays as well as a thin bar of melanophores outlining the base of the caudal fin segmented rays. Dorsal head melanophores consist of one large central melanophore over the rear brain case and often a pair of smaller ones above the eye. Transitional larvae develop solid patches of tiny melanophores on the top of the head, a bar below the eye at about 7 o'clock (and on the iris), and a row of saddle bars below the anterior spinous dorsal fin (no patch on the first dorsal fin spines).

Labrisomus haitiensis ? transitional larva

12.7 mm SL

San Blas, Panama, SB86-408

Notes on Starksia spp.

There are 19 Caribbean species in this genus, many with overlapping fin ray counts (two more in Brazilian waters), and eight may be expected in Panama. Some named species are subdivisions of once wide-ranging geographically-variable species, but many species with presumably very restricted ranges have been recently described (Williams and Mounts 2003).

The Starksia spp. are distinguished from other labrisomid genera by having only 7 to 9 dorsal fin soft rays and usually only 13 pectoral fin rays. Other labrisomids that can share 8 or 9 soft dorsal fin rays include a few Malacoctenus spp., although they have higher modal fin ray counts, i.e. M. delalandei (mode of 10 soft dorsal fin rays), M. gilli (mode of 10 soft dorsal fin rays), M. erdmani (pectoral fin rays 16), and M. macropus (pectoral fin rays 15) and appropriate larval types are identified.

The widespread S. ocellata complex comprises S. occidentalis in the Western Caribbean (20-21,7-8,17-18,14), along with S. ocellata (Florida), S. culebrae (Antilles), S. guttata (SE Caribbean 20-22,8-9,17-18,14), S. variabilis (Colombia), and S. brasiliensis in Brazil.

The S. sluiteri complex comprises the widespread S. sluiteri (18-19,7-9,15-17,13) with localized relatives S. leucovitta (Navassa 18-19,8-9,15-16-17,13), S. melasma (PR St.Croix 18-19-20,7-9,15-16,13), S. multilepis (Noronha 20,8,16-17,13), S. rava (Tobago 19-20-21,7-8-9,16-17-18,13), S. sella (Tobago 18-19,7-9,16-17,13).

There are also the widespread species S. atlantica (18-19-20,7-8,15-16,14), S. nanodes (19-20-21,7-8,16-17,13), S. lepicoelia (19-20-21,7-8-9,16-17,13), S. starcki (20-21,8-9,18-19,13), S. elongata (20-21,7-8-9,17-18,13) and perhaps S. y-lineata (Cayman and Nicaragua 19,7-8,15,13).

S. fasciata is found only in Cuba and the Bahamas (19-20,7-8,15-16,13), and its relative S. smithvanizi only in the Antilles (19-20,7-8,15-16,13), and S. hassi only in the Bahamas/Antilles (deep 19-20,8-9,17,13).

Starksia occidentalis

Diagnosis: Modal fin counts of D-XXI,7-9 A-II,18 Pect-14 indicate Starksia spp. Only S. occidentalis and S. atlantica have a mode of 14 pectoral fin rays and the latter is excluded by having only 15-16 anal fin soft rays. (U)

Analogues:

Description: Body long, somewhat narrow and thin with a large eye and a terminal large mouth. Pectoral and pelvic fins medium length. Ventral melanophores only along the midline, at the thorax and at the pelvic fin insertion, and then in a row along the base of the anal fin, one for each anal fin spine and soft fin ray. The melanophore after the last anal fin ray is larger and often extends deeply. There are no additional melanophores along the ventral midline of the caudal peduncle. Transitional larvae develop solid bars of melanophores radiating from the eye (and onto the iris), most prominently at about 8 o'clock across the mid-jaw and in bands across the top of the head. A small patch of melanophores develops on the base of the first dorsal fin spine.

Starksia occidentalis transitional larva

10.0 mm SL

San Blas, Panama, SB86-608

Starksia nanodes

Diagnosis: Modal fin counts of D-XX,7 A-II,16 Pect-13 indicate Starksia spp. Many species have a mode of 13 pectoral fin rays, but among them only S. nanodes has a strong mode of 7 dorsal fin soft rays. (U)

Analogues:

Description:

Starksia nanodes transitional recruit

10.0 mm SL

Barbados, Henri Valle 2005R21

Starksia sp. A

Diagnosis: Modal fin counts of D-XIX,8 A-II,16 Pect-13 indicate Starksia spp. There are numerous species in the genus that overlap in fin ray counts. This larval type has a large eye and metamorphoses at a particularly small size, less than 8 mm SL.

Analogues:

Description:

Starksia sp. A transitional larva

7.8 mm SL

San Blas, Panama, SB86-1008

Paraclinus fasciatus

Diagnosis: Modal fin counts of D-XXIX A-II,19 and a mode of 13 pectoral fin rays indicates Paraclinus fasciatus (28-31, II,17-20). Two other Caribbean species have all dorsal fin elements spinous (and just two pelvic fin segmented rays): P. cingulatus with 12 pectoral fin rays (27, II,15, no ocelli) and P. naeorhegmis (26, II,15-16, Bahamas only). The remaining species of the genus have a single segmented ray as the last dorsal fin element and a small third pelvic fin segmented ray (vs. only two): P. barbatus, P. grandicornis, P. infrons, P. marmoratus, and P. nigripinnis. (U) C1

Analogues:

Description: Body long, somewhat narrow and thin with a large eye and a terminal large mouth. There is a clear notch in the membrane between the first three dorsal fin spines and the rest of the fin. Pectoral and pelvic fins medium length. Internal melanophores along the dorsal surface of the peritoneum and around the gut near the vent. No dorsal surface melanophores, but a large deep melanophore at the rear of the the braincase (often obscure in well-developed larvae). Some individuals have one or two small melanophores on the opercle at the level of the mid-eye. Ventral melanophores only along the midline: one at the isthmus, one deep and behind the pelvic fin base (often obscure in well-developed larvae), and then in a row along the base of the anal fin, usually one for each anal soft fin ray. This row can be variable, sometimes there is also a melanophore at the base of the second anal fin spine and often the last one or two rays have no melanophore. There are usually between one and three more melanophores along the ventral midline of the caudal peduncle before the start of the accessory caudal fin rays. Transitional larvae develop a

Paraclinus fasciatus larva

8.8 mm SL

San Blas, Panama, SB86-501

Paraclinus nigripinnis

Diagnosis: Modal fin counts of D-XXX,1 A-II,18 and a mode of 13 pectoral fin rays indicates Paraclinus nigripinnis (29-31+1, II,17-19, divided/short opercular spine, one ocellus). A group of species share the single segmented ray as the last dorsal fin element and a small third pelvic fin soft ray (vs. only two): P. barbatus (28-29+1, II,19-20, rare deep-water), P. grandicornis (large orbital cirrhus, 12 pectoral fin rays, no ocellus), P. infrons (26-28+1, II,17-18, no nuchal cirrhi, 12 pectoral fin rays, two dorsal fin spots), and P. marmoratus (28-29+1, II,19-20, three ocelli). The two remaining Caribbean species have all dorsal fin elements spinous and two soft rays in the pelvic fin (P. cingulatus and P. naeorhegmis). (U) C1

Analogues:

Description: Body long, somewhat narrow and thin with a large eye and a terminal large mouth. Pectoral and pelvic fins medium length. Internal melanophores along the dorsal surface of the peritoneum and around the gut near the vent. No dorsal surface melanophores, but a large deep melanophore at the rear of the the braincase (often obscure in well-developed larvae). Some individuals have one or two small melanophores on the opercle at the level of the mid-eye. Ventral melanophores only along the midline: one at the thorax just forward of the pelvic fin insertion, one deep and behind the pelvic fin base (often obscure in well-developed larvae), and then in a row along the base of the anal fin, usually one for each anal soft fin ray (occasionally one for each anal fin spine as well). There is usually a single additional melanophore just behind the last anal fin ray (and not on the ridge of soft tissue before the accessory caudal fin rays).

Paraclinus nigripinnis larva

7.9 mm SL

San Blas, Panama, SB86-616