This species can be distinguished from all its congeners on the basis of vertebral counts (only Lepophidium aporrhox has fewer vertebrae than L. collettei with no overlap in number of precaudal vertebrae, 14-15 vs. 12-13 in L. aporrhox). L. collettei differs further from L. aporrhox in dorsal rays (116-122 vs. 106-115), rudiments on lower gill arch (2-7 vs. 8-12), length of the long (9-11% vs. 13-18%) and short pelvic rays (5-7% vs. 8-12%) in SL; differs from L. brevibarbe in the absence of a distally expanded anterior rib in males or haltere as seen in L. brevibarbe, developed rakers on the lower gill arch (6-8 vs. 4-5), and in having a deeper body; from L. gilmorei by the average number of caeca (5.4 vs. 3.2), total gill raker elements (12-17 vs. 8-9), dorsal fin origin (between neural spines 4-5 and 5-6 vs. between 3-4); from L. marmoratum by caudal vertebrae (51-54 vs. 55-58), short pelvic rays as a percentage of standard length (5-7% vs. 8-12%), and lack of dark spots on the head and body, in rows or otherwise; from the Pacific L. microlepis by average head length (20.8% vs. 24.3% in SL) and long pelvic rays (9-11% vs. 5-8% in SL); on the basis of dorsal rays (116-122), from L. pheromystax (125-133), L. robustum (123-126), and L. stigmatistium (123-131) Ref. 91765.