Amblyceps cerinum differs from its congeners except A. apangi, A. murraystuarti, and A. torrentis in having a truncate caudal fin (vs. forked or strongly emarginate); differs from A. apangi in having a longer adipose-fin base 32.4–38.3% SL (vs. 24.3–32.0), more slender caudal peduncle 9.2–11.2% SL (vs. 11.3–15.4), greater number of post-Weberian vertebrae 41–44 (vs. 38), having the lateral line terminating just posterior to the vertical through the dorsal-fin insertion (vs. extending to the end of the caudal peduncle); differs from A. murraystuarti in having a more slender body 9.2–11.2% SL (vs. 11.6–15.0), longer caudal peduncle 21.9–24.5% SL (vs. 19.6–22.6), with the posterior end of the adipose fin not broadly confluent with the dorsal procurrent caudal-fin rays and separated from them by a distinct notch (vs. adipose fin broadly confluent with dorsal procurrent caudal-fin rays and not separated by a distinct notch); differs from A. torrentis in having a more slender body 9.2–11.9% SL (vs. 15.3–17.3% SL), slender caudal peduncle 9.2–11.2% SL (vs. 13.8–15.6), the upper jaw longer than the lower jaw (vs. jaws equal), and an incomplete lateral line terminating at the posterior base of the dorsal fin (vs. a complete lateral line terminating at the base of the caudal fin) (Ref. 85525).