Description: Body relatively thin, long and narrow with a large eye and a medium-sized low terminal mouth. Pectoral fins long, reaching past the vent. Pelvic fins long, reaching about two-thirds of the way to the vent without an obvious frenum or cup. Dorsal and anal-fin bases medium length, caudal peduncle long and narrow and only 4-6 procurrent caudal-fin rays (4-5 spindly). Very lightly marked along the ventral midline: melanophores absent from thoracic and pelvic region and present as a short row of two to four along anal-fin base between the third and seventh element (variably paired and variably one per side) and then one large melanophore just after the last anal-fin ray. Some individuals have a surface melanophore just forward of the anal-fin origin. Internal melanophores at the dorsal surface of the swim bladder. Series of transitional larvae show the eye remains round. Transitional larvae first develop two arcs of melanophores across the top of the head between the eyes, subsequently two more arcs develop behind the eyes and then two bars of melanophores develop below the eye (corresponding iris melanophores at about 12, 2, 5, and 7 o'clock). A scattering of tiny melanophores develops along the upper jaw and around the nasal bones.
Analogues: (anal-fin base row and post-anal-fin spot only)
Diagnosis: Fused pelvic fins and modal fin-ray counts of D-VII,11 A-8-9 and Pect-16 indicate Tigrigobius pallens and Gobiosoma yucatanum. This low fin-ray count matches only a few species in the large Gobiosoma/Tigrigobius/Elacatinus group. The modal count overlaps the lower range for T. saucrus and T. dilepis. However, individuals of this larval type range as low as D-VII,10 A-8 Pect-15. G. yucatanum (Pect-16 with range 15-18) occurs only from Yucatan to Honduras. Gobiosoma grosvenori can overlap these lower counts, but is found only in Florida, Bahamas, and Venezuela. (PE) G7ab
