This species is distinguished from all other congeners by the following set of characters: continuous lateral-line canal with single row of pores; orbit with 2 cirri; no true ocellus on anterior part of dorsal fin; low dorsal fin, not elevated anteriorly in either sex; absence of narrow membrane along anterior edge of 1st dorsal-fin spine. Neoclinus monogrammus differs from Neoclinus nudiceps in having the following characters: lateral-line canal 9-15 pores and reaching to below 6th to 9th dorsal-fin spine (vs. 3-5 pores, reaching to below 3rd to 4th dorsal-fin spine); counts of supraorbital cirri tips, the anterior and posterior cirri with 10-28 and 3-14 tips, respectively (vs. 2-6 and 1-2 tips, respectively); male color pattern on head with scattered reddish spots (vs. no conspicuous spots); body depth in proportion to standard length 11.3-13.4% (vs. 13.0-15.4%); head depth in proportion to head length 51.2-58.0% (vs. 56.6-60.6%) (Ref. 85569).