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Enneanectes
family Blenniidae
family Labrisomidae
family Chaenopsidae
Triplefins are tiny blenny-like fishes that skate around over rocks and coral heads on reefs everywhere in the Caribbean. Although a couple of species occur on deeper reefs and walls, most triplefins can be found in shallow water, often on rocks and pilings just below the surface of the water. There is a single Atlantic genus, Enneanectes, presently with eight species, some of which are difficult to distinguish underwater. Prior to 2013, five species were known from the region, but identifications were difficult based on the keys available. In 2013, three new species were described, with the assistance of DNA-barcoding, and a revised key developed. Triplefins on the reef are identified to species mostly by scale patterns and markings, i.e. characters developing after settlement and inapplicable to larvae. Some species are wide ranging, although several have restricted distributions within the Caribbean region. Triplefin larvae share most features and, since there is some overlap in fin-ray counts, it is likely that DNA-sequencing is necessary for most species identifications. Nevertheless, modal fin-ray counts do differ and some larvae from known locations may be narrowed down to one or two candidate species by meristics alone.
 
Larval tripterygiids resemble the very common small labrisomid larvae, but they differ from all other families by having prominent melanophores on the upper caudal peduncle and three separate dorsal fins. They can be characterized by their pointed snout, long dorsal and anal fins with flexible spines (dorsal fin divided), a short and narrow caudal peduncle, long strand-like pelvic fins, the absence of spines on the head, and light markings (basically a row of melanophores along the anal fin base and along the dorsal midline of the caudal peduncle). Larval tripterygiids have large round eyes, in contrast to many labrids, scarids, and gobies, in which the eye can be small or narrowed.
Early-stage larvae
Triplefins have demersal brooded eggs and hatch as well-developed larvae around 3-4 mm in length. The early-stage post-flexion larvae can be recognized by a moderately long and narrow body with a small pointed head, medium mouth, prominent jaw angle, large rounded eye, no head spines, snout-to-vent length slightly less than half of body length, long fin bases, and early-forming posterior dorsal and anal-fin elements. Pigmentation is distinctive, with a single midline surface melanophore over the rear braincase and a short row of two or three melanophores along the dorsal and ventral midlines of the caudal peduncle. In addition, there is a row of three ventral midline melanophores along the base of the rear portion of the developing anal fin. There are internal melanophores at the sacculus, over the swim bladder, and around the gut near the vent.
Enneanectes sp. larva
4.7 mm SL
early-stage larva
San Blas, Panama, SB86-1227
 
 
 
 
Enneanectes species
 

E. altivelis: deeper reefs and walls, occasional (widespread in Caribbean); mode D III+XI+8 and A II,15 P-14.

E. atrorus: deeper reefs and walls, occasional (widespread in Caribbean); mode D III+XII+9 and A II,16 P-15.

E. boehlkei: shallow reefs and shore, abundant (FL, Bahamas, W. Caribbean, Antilles S. to St. Kitts); mode D III+XII+8 and A II,16 P-15.

E. deloachorum: shallow reefs and shore, occasional (SE Caribbean); mode D III+XII-XIII+9 and A II,16-17 P-15.

E. jordani: reefs, rare (Bahamas, W. Caribbean, Antilles); mode D III+XII+7 (occ. XI and/or 8) and A II,15 P-15.

E. matador: shallow reefs and shore, occasional (W. Caribbean, Antilles); mode D III+XII+8-9 and A II,16-17 P-15.

E. pectoralis: very shallow shoreline, occasional (FL, Bahamas, Antilles); mode D III+XII+7 and A II,15 P-15.

E. wilki: shallow reefs and shore, common (Windward Islands only, Dominica to Tobago); mode mode D III+XII+8 and A II,16 P-15.

Enneanectes altivelis
 
Diagnosis: Three dorsal fins with a modal fin-ray count of D-III,XI,8 occ 7 A-II,15 P-14 indicates Enneanectes; generally lower fin-ray counts characterize E. altivelis, i.e. the 15/14 anal-fin/pectoral-fin soft ray combination and only eleven second-dorsal-fin spines.
Description:
Enneanectes sp. larva
8.6 mm SL
internal melanophore pattern
San Blas, Panama, SB86-509
Enneanectes boehlkei
 
Diagnosis: Three dorsal fins with a modal fin-ray count of D-III,XII,8 A-II,16 P-15 indicates Enneanectes; the modal fin-ray count for E. boehlkei falls in the middle of the range for the genus and is shared by E. matador and E. wilki (the latter does not overlap geographically). E. boehlkei is by far the most common shallow-water triplefin found within its range (FL, Bahamas, N. and W. Caribbean, Antilles south to St. Kitts).

Description: Body long, narrow, and thin with a large round eye, pointed snout, and medium 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, reaching about half-way to the vent. On the head, there is a single midline surface melanophore over, as well as a prominent internal saccular melanophore; on the ventral aspect, there is an isthmus melanophore and a deep pelvic melanophore. The anal row is . The caudal peduncle has the characteristic pair of dorsal midline melanophores and a pair of ventral midline melanophores. Internal retroperitoneal melanophores are only visible on less-developed larvae.

Transitional larvae develop metamorphic melanophores in a pattern of bands over the head and a single nuchal band, followed by a short bar below the eye at 5 o'clock and a broad oblique stripe from the eye across the anterior half of the jaws.

Analogues: Larvae are distinguished from those of all other similar families by the three dorsal fins as well as by melanophores on the dorsal midline of the caudal peduncle. Melanophore patterns do not discriminate between species- meristics usually do and DNA sequencing may be necessary for a firm species ID.

Enneanectes sp. larva
8.6 mm SL
internal melanophore pattern
San Blas, Panama, SB86-509
Enneanectes deloachorum
 

Diagnosis: Three dorsal fins with a modal fin-ray count of D III+XII-XIII+9 and A II,16-17 P-15 indicates Enneanectes; this modal fin-ray count for E. deloachorum is higher than most congeners; themode of 9 third dorsal-fin rays is shared only with E. atrorus (also many E. matador). It mostly replaces E. boehlkei within its range- the Windward Islands of the Lesser Antilles, from Dominica to Bonaire.

Description:
Enneanectes sp. larva
8.6 mm SL
internal melanophore pattern
San Blas, Panama, SB86-509

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