operculum: longitudinal ridge + several oblique ridges
A: tiny, 4
C small, black
Microphis brachyurus lineatus (Kaup, 1856)
Head long (15-22% of SL), without spines; snout very long (50-67% of head length), slender (~ 11% of snout length), straight; mouth strongly oblique, rising above tip of snout; well developed horizontal ridge across center of operculum, with several oblique ridges below it; ridges along upper side of body and of tail not joined; ridge on midside of body joins ridge on lower side of tail; lower body ridge ends at level of anus, ridges spiny in juveniles, +/- small spines in adults; trunk rings 17-21, tail with 20-26 rings; oval plates between body rings without longitudinal keels; brood pouch under trunk, with vertical plates that are not folded; dorsal fin long, 37-54 rays, origin on trunk; pectoral broad base, short fin, central rays shorter than outer rays, 17-23 rays; anal fin tiny, 4 rays; tail fin small, 9 rays.
Brownish grey; dark stripe along snout, through eye, across operculum and along upper back to dorsal fin; dorsal fin with brown vertical streaks between rays; tail fin blackish.
Size: 19.5 cm.
Habitat: estuaries and freshwater.
Depth: shallow 0-10 m.
A West Atlantic species that has passed through the Panama Canal to Panama Bay and spread westward to Costa Rica.