Analogues: (VMS4: jaw angle, thorax, anal fin, caudal peduncle) Based on the appearance of transitional recruits, larval C. alloides likely share the VSM4 melanophore pattern. The reduced anal-fin-ray count separates larvae from the other sand gobies. Transitional C. alloides share a spotted head pattern with C. thrix and C. eidolon vs. stripes on most other sand gobies, as well as a prominent melanophore(s) at the 8 o'clock position on the orbital rim (on the majority of individuals), often early in transition. C. alloides diverge early from C. thrix and C. eidolon, having the jaw angle melanophores and the mid-body bar.
Diagnosis: Modal fin-ray counts of D-VI,10 A-8-9 and Pect-16-17 match Coryphopterus alloides, along with a number of other regional gobies. Some Lythrypnus species can have as many as 16 pectoral-fin rays, but only rare individuals would have 17 (17 is frequent in C. alloides). Bathygobius curacao can overlap the fin-ray count but larvae have prominent internal melanophores. Coryphopterus kuna has D-VI,9 A-9 and pect-15. Other gobies which share the median-fin-ray count have more pectoral-fin rays: Lophogobius cyprinoides with 17-19 (16-20), Priolepis hipoliti (17-19), Bathygobius mystacium and B. soporator (both with mode 19-20). The only seven-spined goby with a similar modal fin-ray count is Gobiosoma grosvenori (16-18). Some distinguishing features of adult C. alloides are present on recruits and small juveniles, such as the characteristic mid-body bar and dorsal-fin spot, however recruits do not have the diagnostic divided pelvic fins. (DNA)
