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| 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. |
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| 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. |
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| 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. |
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| Enneanectes
sp. larva |
| 4.7 mm SL |
| early-stage larva |
| San Blas, Panama, SB86-1227 |
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E.
altivelis: deeper reefs and walls, occasional
(widespread in Caribbean); mode D III+XI+8 and
A II,15 P-14.
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E.
atrorus: deeper reefs and walls, occasional
(widespread in Caribbean); mode D III+XII+9 and
A II,16 P-15.
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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.
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E.
deloachorum: shallow reefs and shore,
occasional (SE Caribbean); mode D III+XII-XIII+9
and A II,16-17 P-15.
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E.
jordani: reefs, rare (Bahamas, W. Caribbean,
Antilles); mode D III+XII+7 (occ. XI and/or 8)
and A II,15 P-15.
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E.
matador: shallow reefs and shore, occasional
(W. Caribbean, Antilles); mode D III+XII+8-9 and
A II,16-17 P-15.
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E.
pectoralis: very shallow shoreline, occasional
(FL, Bahamas, Antilles); mode D III+XII+7 and
A II,15 P-15.
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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.
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| 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. |
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| Description:
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| Enneanectes
sp. larva |
| 8.6 mm SL |
| internal melanophore
pattern |
| San Blas, Panama, SB86-509 |
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| 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). |
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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.
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| Enneanectes
sp. larva |
| 8.6 mm SL |
| internal melanophore
pattern |
| San Blas, Panama, SB86-509 |
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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.
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| Description:
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| Enneanectes
sp. larva |
| 8.6 mm SL |
| internal melanophore
pattern |
| San Blas, Panama, SB86-509 |
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All contents © copyright 2006-2014
All rights reserved
www.coralreeffish.com by
Benjamin Victor
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