Limatulichthys nasarcus differs from L. griseus by the possession of the following characters: anterior abdominal plates half the size of those at center of abdomen (vs. plates similar in size); spots across the entire dorsum, including snout and head, less than half of diameter of naris (vs. indistinct spots larger or equal than diameter of naris); lateral portion of head and opercle with dark well-defined spots, larger than those on dorsum (vs. spots on lateral portions of head and opercle equal in size to those on remainder of body); profile of snout in dorsal view broadly rounded (vs. acutely triangular); head longer (21.4-24.2 SL vs. 17.7-21.0%); and longer anal fin (15.7-18.0 SL vs. 13.7-15.6%) (Ref. 97714).