This species is distinguished from its congeners by the following characters: marmorate flank pattern in live, fully grown ammocoetes, and in some adults (vs. plain colour pattern); with 3 velar tentacles (vs. most similar species L. lanceolata with 5 and L. ninae with 5-7); without posterial teeth (vs. rarely absent, usually a single incomplete row with up to 23 teeth in L. ninae); with less trunk myomeres between last branchial opening and anus 54-57 (vs. 57-64 in L. lanceolata, 57-61 in L. ninae); less trunk myomeres between last branchial opening and first dorsal fin origin 28-32 (vs. 32-36 in L. lanceolata, 32-35 in L. ninae); less trunk myomeres between last branchial opening and second dorsal-fin origin 42-46 (vs. 46-50 in L. lanceolata, 45-49 in L. ninae); differs from L. zanandreai by lacking posterial teeth (vs. usually present, very rarely absent); differs from L. fluviatilis and L. planeri by having a bicuspid middle endolateral tooth (vs. almost always tricuspid) and the infraoral lamina with 5 teeth (vs. usually 7-9, very rarely 5-6) (Ref. 115563).