This species is distinguished from all its congeners, except operculatum by the following characters: maxillary barbel is smaller than half-length of the head (vs. larger than half-length of the head); tips of pectoral-fin rays extending beyond the interadial membrane (vs. not extending beyond interadial membrane); skin flap in the posterior margin of the opercle pointed and long (vs. round an short); fleshy flap at the base of the maxillary barbel located anteriorly, it is thick, prolonged up to the snout and with distal margin straight (vs. fleshy flap located posteriorly, thin, restricted to the maxilla and with distal margin rounded); caudal fin with a transversal black bar distally (vs. no black bar) differs S. operculatum by having a midlateral line of 6-9 rounded black blotches larger than opercle (vs. midlateral line of 10-14 rounded black blotches as large as or smaller than opercle), tip of nasal barbel usually extending beyond anterior margin of eye (vs. never reaching anterior margin of eye), tip of maxillary barbel extending between anterior and posterior margins of interopercle (vs. tip never surpassing anterior margin of interopercle) (Ref. 122319).