Distinguished from all congeners by having 12 branched caudal-fin rays; from all Lithoxus except Lithoxus lithoides by having four branched anal-fin rays, and five interdorsal plates; from all Lithoxus except Lithoxus lithoides and Lithoxus stocki by having a convex posterior membranous extension of the adipose fin; from all Lithoxus except Lithoxus lithoides and Lithoxus bovallii by having medial premaxillary teeth with an enlarged and widened cusp; from all Lithoxus except Lithoxus lithoides, Lithoxus stocki and Lithoxus boujardi by having an obliquely truncate to slightly emarginate caudal; from Lithoxus lithoides by having a mode of 24 supramedian plates and a mode of 18 (range 16-25) hypertrophied cheek odontodes; and from Lithoxus pallidimaculatus and Lithoxus surinamensis by the presence of adipose fin (Ref. 79075).