Diagnosis: Male individuals of Laimosemion mabura are similar to those of L. dibaphus, and can be distinguished from all other congeners by possession of bluish black pigmentation on the caudal peduncle (vs. never this coloration); L. mabura is distinguished from L. dibaphus by possession of a yellowish (vs. light blue) pigmentation in the dorsal- and caudal-fin and dorsal-fin pattern having broad defined stripes (vs. dots); Laimosemion mabura further differs from L. dibaphus by pelvic fin short, posterior tip not reaching urogenital papilla (vs. long, tip reaching between base of 2nd and 3rd anal-fin rays in male, between urogenital papilla and base of 2nd anal-fin ray in female) and 25-27 (vs. 28-31) caudal-fin rays (Ref. 119333).