Distinguished from all its congeners except Corydoras arcuatus, Corydoras narcissus, and Corydoras gracilis, by having a long, arched, dark stripe, running parallel to the dorsal profile and extending at least from the anterior margin of the first dorsolateral body plate to the caudal peduncle. Can be diagnosed from Corydoras arcuatus, Corydoras gracilis, and Corydoras narcissus in having the arc-like stripe terminating posterior to the orbit (vs. extending onto snout). Further differs from Corydoras arcuatus by having fewer free vertebrae (21 vs. 27); lateral profile of the snout distinctly rounded (vs. nearly straight); a greater preadipose distance (84.0-86.7% SL, vs. 82.9-83.8% SL); and the posterior limit of the cleithrum at a vertical through the dorsal-fin spinelet (vs. between the third and fourth dorsal-fin rays); from Corydoras gracilis by having fewer free vertebrae (21 vs. 27); arched stripe extending posteriorly to the base of the lower caudal-fin rays (vs. reaching the base of the upper caudal-fin rays); and the second infraorbital contacting only the sphenotic (vs. contacting both the sphenotic and compound pterotic); from Corydoras narcissus in having the arched stripe extending posteriorly across the lower caudal-fin rays (vs. extending over the lower caudal-fin rays); lateral profile of the snout distinctly rounded (vs. nearly straight); and minute and weak pectoral-spine serrations (vs. large and strong serrations) (Ref. 83456).