Diagnosis: The modal fin-ray count of D-XXI,12 A-II,21-22 and P-13 indicates Labrisomus filamentosus. Only M. boehlkei share the high dorsal-fin count, but they have 15 pectoral-fin rays. Ecology: The quillfin blenny is an uncommon blenny found on deep reef dropoffs. The species is found in the Bahamas and most of the Caribbean, but not Florida, the Gulf of Mexico, or the SW Caribbean across to Venezuela. Unfortunately, the 19, 20, and 21-spined Labrisomus are very similar morphologically and are frequently confused in guidebooks and photographs. All six species share the blunt-headed and goggle-eyed appearance, at least as juveniles, i.e. the snout length (bony orbit to jaw tip) is less than two-thirds of the orbit diameter. Adult quillfin blennies are easily recognized in the field by greatly-extended spines at the front of the dorsal fin and a prominent opercular ocellus. Juveniles may be difficult to identify, since the distinguishing markings for each species are either not well-developed or shared by other species at this early stage. L. filamentosus larvae are unknown in collections. Description: Larval L. filamentosus have not been identified. Analogues: Juvenile L. filamentosus have not been identified, but, since juvenile L. haitiensis share the long pelvic fins and most markings and can also have an ocellus-like spot on the operculum, it is possible that L. filamentosus will only be distinguished by fin-ray counts: their extra dorsal soft-fin ray (dorsal elements of 33) and only 13 pectoral-fin rays (vs. 14).
