This moderately large, slender linear-denticled Etmopterus species is distinguished from its congeners within the E. lucifer clade having the length of its anterior flank marking branch being much longer relative to its posterior branch (vs. all other members of this genus, except for two species, having the posterior branch equal or longer than the anterior branch. E. lailae differs from the two species (E. lucifer and E. sculptus) with an anterior branch relatively longer than the posterior branch by having a higher spiral valve count 14-16 (vs.8-9); a slightly lower precaudal vertebral count, 53-57 (vs. 55-64); lower number of teeth on the lower jaw 26-28 (vs./ 30-43); and by lacking dermal denticles between the nostrils on the ventral snout surface and on the dorsal fins (vs. denticles present on the snout and dorsal fins) (Ref. 116235).