Species: Microdesmus retropinnis, Double-spotted worm-goby, Rearfin wormfish

Microdesmus retropinnis Jordan & Gilbert, 1882

Rearfin wormfish, Double-spotted worm-goby

Slender, wormlike, body height 3-9% of SL; tail (without fin) < 50% of SL; eyes not tiny, on side of head, not skin covered; snout rounded; snout and jaw with pronounced longitudinal swollen muscular ridges; mouth small, little oblique, lower jaw strongly projecting, a small fleshy knob at tip of chin; lips with a restricted free flange at sides; teeth partly in 3 rows; gill opening large (not tubular), but < base of pectoral; dorsal fin spines evenly spaced, 47-49 elements, origin ~ 2 head lengths behind head, almost midway between tip of lower jaw and anus; anal II, 28-32; pectoral 10 rays, fin short; pelvics I, 3, shorter than pectorals; tail fin rounded, as long as head; dorsal and anal fins confluent with tail fin; scales small, non-overlapping, well separated; at base of dorsal and anal fins scale rows diverge outwards and backwards; scales with 39 radiating lines.