Native to Guyana, where it may be restricted to the Potaro River, a major tributary within the Essequibo watershed.

It was described from aquarium specimens which were said to have been collected in ‘very small water courses of the Amazon’, but the type locality was corrected to ‘Guyana-Essequibo, Potaro River, Kuribong trail’ by Nijssen and Isbrücker (1980).

C. guapore is a sought after aquarium fish although it is not often traded. It exhibits slightly different behaviour to the majority of congeners in that it tends to form aggregations in midwater and spends a large proportion of its time away from the substrate. Its morphology exhibits corresponding adaptations towards a pelagic existence with a relatively large eye, a more terminal mouth position, more strongly-forked caudal-fin, and more symmetrical body shape than most other Corydoras species.

The majority of records derive from the Río Apure watershed in southwestern Venezuela, where C. habrosus has been collected in the states of Portuguesa, Cojedes, Barinas, Guárico, and Apure. Its distribution in Colombia is less clear but it is known with certainty from the Río Arauca and Río Casanare, the latter a tributary of the lower Río Meta, and it makes sense that it should also be found in other left bank Orinoco affluents between the Meta and Apure, which include the ríos Cinaruco and Capanaparo.

This species’ range is unclear with collection records scarce, although it certainly occurs in the ‘Tres Fronteras’ region of the western Amazon river basin where the borders of Brazil, Colombia, and Peru meet.

Type locality is ‘Lakes of the Isla de Mocagua, Amazon River, near Leticia, Comisaría del Amazonas, 3°54’S, 70°14’W, Colombia’.

Known from southern Sao Paulo to northern Santa Catarina states in eastern Brazil, including the rios Jaraguá, Iguaçu, Tejuco, Ribeira de Iguape, Guabiroba, Tibagi, Capivari, Lindo, Itapocu, São Pedro, and upper Rio Paranapanema.

This species appears superficially similar to a number of congeners including C. ambiacus, C. agassizii, C. brevirostris, C. delphax, and C. melanistius.

Among these C. ephippifer seems to be unique in that all fins except the dorsal are transparent and lack markings.

Unfortunately, precise diagnostic characters cannot currently be provided since we’ve been unable to obtain the type description, and little has been
Characters said to separate it from species such as C. ambiacus, C. agassizii, C. brevirostris, C. ephippifer, and C. melanistius include a combination of relatively elongated snout, dark spots on body fading in adults, dark anterior dorsal-fin patch extending to upper extremity of fin, and presence of spots in the caudal-fin.

This species is not well-documented but is said to differ from the comparable C. punctatus by possessing larger dark markings on the body which may form an irregular midlateral stripe in some specimens.

Unfortunately diagnostic characters cannot be provided since we’ve been unable to obtain the type description, and little has been written about the species since it was published.

This species occurs alongside the similar-looking congener C. oiapoquensis in nature, from which it can be told apart by the following combination of characters: larger adult size; narrower body (body breadth fits 4.0-4.4 times in standard length vs. 3.4-3.8 times in C. oiapoquensis); shorter pectoral spine (3.4-3.8 times in SL vs. 2.7-3.2 times); longer snout (1.7-1.9 times in SL vs. 2.0-2.2).

C. caudimaculatus may be confused with the congener C. similis but can be told apart by possession of a well-defined, blackish spot on the caudal peduncle vs. a ‘smudged’ bluish marking.

C. guapore also has a comparable colour pattern but possesses a distinctly rounded snout and tends to swim above the substrate.