peppered corydoras

conservation

Conservation status. Populations of Corydoras paleatus are known from at least three relatively wide regions, comprising territories from Argentina, Brazil and Uruguay, and no imminent threat is suspected for the species as whole, therefore, according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2014), C. paleatus can be classified as Least Concern (LC).

Revisionary study of the armored catfish Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species

description

Description. Morphometric data presented in Table 1. Head compressed with slightly convex dorsal profile; triangular in dorsal view. Snout slightly pointed. Head profile convex from snout to anterior nares; roughly straight from this point to tip of posterior process of parieto-supraoccipital. Profile slightly convex along dorsal-fin base. Postdorsal-fin body profile concave to adipose-fin spine; markedly concave from this point to caudal-fin base. Ventral profile of body nearly straight from isthmus to pectoral girdle; slightly convex from this point until pelvic girdle. Profile nearly straight from pelvic girdle to base of first anal-fin ray; slightly concave until caudal-fin base. Body roughly elliptical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin. Eye rounded, located dorso-laterally on head; orbit delimited dorsally by frontal and sphenotic, ventrally by infraorbitals. Anterior and posterior nares close to each other, only separated by flap of skin. Anterior naris tubular. Posterior naris close to anterodorsal margin of orbit, separated from it by distance equal to diameter of naris. Mouth small, subterminal, width nearly equal to

Revisionary study of the armored catfish Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species

diagnosis

Diagnosis. Corydoras paleatus can be distinguished from its congeners, with exception of C. armatus (Günther, 1868) and C. microcephalus, by the presence of perpendicularly directed serrations along entire posterior margin of the pectoral spines (vs. serrations directed towards pectoral-spine origin; serrations directed towards pectoral-spine tip; perpendicularly directed serrations, if present, bifid or restricted to proximal region of pectoral spine); from C. armatus by the absence of contact between infraorbital 2 and compound pterotic (vs. presence); from C. microcephalus by the presence of a longitudinal series of three large black blotches along midline of flank (vs. four or five midline blotches in C. microcephalus). Additionally, C. paleatus can be distinguished from C. cohui Myers & Weitzman, 1954, C. diphyes Axenrot & Kullander, 2003, C. flaveolus, C. froehlichi, C. gryphus Tencatt, Britto & Pavanelli, 2014, C. habrosus, C. lacrimostigmata Tencatt, Britto & Pavanelli, 2014, C. longipinnis Knaack, 2007 and C. lymnades Tencatt, Vera-Alcaraz, Britto & Pavanelli, 2013 by having the anterior region of the dorsal fin black (vs. with black spots or bars); from C. carlae Nijssen

Revisionary study of the armored catfish Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species

discussion

Remarks. In the review of Corydoras conducted by Nijssen & Isbrücker (1980), the authors restricted the type-locality of C. paleatus, however this was done without any justification. Despite this region has been part of the places visited by Darwin on his voyage (Darwin, 1839), there is no evidence for such a restriction of the type-locality. Unfortunately, there are no concrete evidences that lead to the exact type-locality where Darwin may have collected C. paleatus, but it is more likely that this species has been collected in Uruguay and not in Argentina. Calviño (2007) rescued the type-locality of four species collected by Darwin during the voyage of the Beagle. The author analyzed potential locations where Darwin would have collected, finding the Laguna del Diario, a lake which supplies the city of Maldonado, where Darwin stayed for more than two months and collected several fish species. Jenyns (1842) mentions that “ in a lake suddenly drained ” (Darwin (1839: 134) mentioned “ nearly drained ”) many fish samples were collected, which makes sense since the fish sampling tends to be more practical in low volume sites. Corydoras paleatus inhabits the Laguna Del Diario (Calviño

Revisionary study of the armored catfish Corydoras paleatus (Jenyns, 1842) (Siluriformes: Callichthyidae) over 180 years after its discovery by Darwin, with description of a new species