Corydoras areio

biology_ecology

Ecological notes. In the rio Taboco and rio Taquari basins, Corydoras areio was generally found inhabiting small streams (Fig. 6), mainly associated with deep, lentic habitats during the day, ranging from about 50 cm to 1 m depth, with substrate predominantly composed of sand. During day, the species displays a more active behavior, swimming away at the sign of any movement, even from outside of the water. On the other hand, the species can be easily observed and captured in shallow beaches of streams (about 10 cm depth) during the night, where they stay nearly motionless. At the beaches of the ribeirão dos Veados (Fig. 6 A), the species was observed in syntopy with C. polystictus and Corydoras aff. polystictus. The species was rarely captured in the main channel of the rio Taboco (Fig. 6 B), where it is also associated with the sandy substrate of the river banks. In the rio Taboco basin, C. areio occurred in syntopy with Corydoras aff. aeneus (Gill, 1858). In most collecting sites, C. areio specimens were observed burying themselves in the sandy substrate, especially during capture attempts. Another interesting feature of C. areio observed in natural habitat is the presence of tra

Taxonomic review of the typical long-snouted species of Corydoras (Siluriformes: Callichthyidae) from the río de La Plata basin

description

Description. Morphometric data are presented in Tab. 1. Head compressed with convex dorsal profile, roughly triangular in dorsal view. Snout conical conspicuously pointed. Head profile slightly concave from tip of snout to anterior nares, ascending straight to slightly convex from this point to anterior portion of parieto-supraoccipital; slightly convex 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, concave from this point to caudal-fin base. Ventral profile of body nearly straight from isthmus to pectoral girdle, and slightly convex from this point until pelvic girdle. Profile nearly straight from pelvic girdle to base of first anal-fin ray, roughly concave until caudal-fin base. Body roughly elliptical in cross section at pectoral girdle, gradually becoming more compressed toward caudal fin. Eye rounded, located dorsolaterally on head. Orbit delimited anteriorly by lateral ethmoid, anterodorsally by frontal, posterodorsally by sphenotic, posteriorly by infraorbital 2, and ventrally by infraorbital 1. Anterior and posterior nares close to each other, onl

Taxonomic review of the typical long-snouted species of Corydoras (Siluriformes: Callichthyidae) from the río de La Plata basin

diagnosis

Diagnosis. Corydoras areio can be distinguished from its congeners, except for the species within lineage 1 sensu Alexandrou et al. (2011), by the presence of the following features: temporal sensory canal in sphenotic with two pores anteriorly to the branch that gives rise to infraorbital canal (vs. with a single pore), upper tooth plate of branchial arch with three or four series of teeth (vs. two series of teeth), area at the corner of the mouth, ventral to the maxillary barbel, with a fleshy flap (vs. fleshy flap absent). Corydoras areio can be distinguished from the species belonging to the lineage 1, except for C. acutus Cope, 1872, C. cervinus Rössel, 1962, C. maculifer Nijssen, Isbrücker, 1971, C. oxyrhynchus Nijssen, Isbrücker, 1967, C. saramaccensis Nijssen, 1970, C. vittatus Nijssen, 1971 and C. zawadzkii Tencatt & Ohara, 2016, by the absence of large patches of black pigmentation on the body (vs. presence in the remaining congeners). Corydoras areio is diagnosed from C. acutus, C. cervinus, C. maculifer, C. vittatus and C. zawadzkii by the presence of blotches on flanks not aligned in longitudinal series (vs. aligned in longitudinal series, sometimes forming continuous

Taxonomic review of the typical long-snouted species of Corydoras (Siluriformes: Callichthyidae) from the río de La Plata basin

discussion

Remarks. An interesting point concerning Corydoras areio is its exact type-locality, since Knaack (2000) did not provide an exact locality, pointing that the species was captured in streams of the “ Córr. ” (surely an abbreviation for córrego) Areio, in the vicinity of Vila Nova, east of Cuiabá, Mato Grosso State, Brazil. According to Knaack (2000: 47 – 48), C. areio seems to be found in two streams that cross the road MT- 373, one of them in the kilometer 8.5 and the other one in the kilometer 13.5, near the city of Poxoréo. Searches for “ Vila Nova ” in Mato Grosso only resulted in a small town at the margins of the rio das Garças, upper rio Araguaia basin, which seems unlikely to be related to the C. areio type-locality. Even though it was not possible to track these exact points, the córrego Areia basin, tributary from the rio Poxoréo, itself a tributary from rio Vermelho, where the rio São Lourenço flows seems the most plausible potential area for the type-locality, especially considering that the córrego Areia itself and some of its tributaries cross the road MT- 373 close to the city of Poxoréo (in a range of about 10 kilometers). In a recent collecting trip led by LFCT, the

Taxonomic review of the typical long-snouted species of Corydoras (Siluriformes: Callichthyidae) from the río de La Plata basin