A new arc-striped species of Corydoras Lacépède, 1803 (Teleostei: Callichthyidae) from the Peruvian Amazon.

A new Corydoras is described from the Blanco and Ucayali river basins in Peru. The new species can be distinguished from its congeners by having the following features: (I) posterior margin of dorsal-fin spine with laminar serrations directed towards the origin of the spine; (II) a long, wide, arched, and continuous black stripe, which runs parallel to the dorsal profile of the body, extending at least from the region below anterior origin of dorsal fin to the anterior half of the ventral caudal-fin lobe; (III) a black stripe transversally crossing the eye, forming the typical mask-like blotch; mask clearly not fused to arched stripe in most specimens; some specimens with mask separated from arched stripe by a thin line around the suture between neurocranium (in the region composed by the posteroventral margin of parieto-supraoccipital plus the posterodorsal margin of the compound pterotic) and first dorsolateral body plate; (IV) posterior margin of pectoral-fin spine with laminar serrations directed towards the origin of the spine; (V) pointed snout, presenting a long mesethmoid, with anterior tip larger than 50% of the entire length of the bone; and (V) ventral surface of trunk covered by small, non-coalescent platelets. A discussion on the possible positive adaptive value of the arc-striped color pattern is also provided.