Bartail Goby

Diagnosis: Modal fin-ray counts of D-VI,10 A-10 and Pect-18-20 with fused pelvic fins indicate the 10/10 Coryphopterus sand gobies, i.e. Coryphopterus thrix, C. glaucofraenum, C. tortugae, C. bol, C. dicrus, and C. eidolon. The distinguishing features of adult C. thrix are mostly not present on recruits and small juveniles.

Analogues: The 10/10 sand goby clade share fin-ray counts, morphology, and most markings as larvae and new recruits. C. thrix and C. eidolon diverge during transition as they develop scattered spots on the top of the head vs. stripes on most other sand gobies, as well as a prominent melanophore(s) at the 7-8 o'clock position on the orbital rim (on the majority of individuals), often early in transition. Both species have no jaw angle melanophores, at least as recruits (larval pattern uncertain). C. thrix juveniles larger than about 12 mm SL begin to develop the characteristic speckling of small patches of melanophores (some 0.05-0.1 mm) over the dorsal aspect of the eye vs. a few large round and comma-shaped patches (0.3-0.5 mm) in C. eidolon and other sand gobies. An additional difference between the small juveniles (>10 mm SL) of these two very similar species is the uniform size of the head melanophores in C. eidolon vs. C. thrix, where the lowest melanophores, just behind the eye, are distinctly larger than the adjacent sets of dorsal melanophores. Recruits of the hovering gobies Coryphopterus personatus, C. hyalinus, and C. lipernes also do not have stripes on the head at transition; nevertheless they can be distinguished from transitional C. thrix by developing melanophores around the vent and in a wide band from the eye to the maxilla.

Coryphopterus thrix, the bartail goby, is a species of goby found in the Western Atlantic Ocean from southern Florida and the Bahamas all the way to Brazil.

This species reaches a length of 5.0 cm (2.0 in).