Two new species of the Hypostomus cochliodon group (Siluriformes: Loricariidae) from the rio Paraguay basin, with a redescription of Hypostomus cochliodonKner, 1854

Abstract

Hypostomus cochliodon group is a monophyletic clade of 20 valid species of Neotropical armored catfishes that is widely distributed throughout South America. Recently, specimens identified as H. cochliodon from the type locality and nearby localities were examined, and found to include representatives of more than one species. A redescription of H. cochliodon is provided, with a description of two new species, one from the Bodoquena Plateau and another from several localities of the rio Paraguay basin. A lectotype for H. cochliodon is designated herein, since the previous designation is invalid. Hypostomus cochliodon is diagnosed from all other species of the H. cochliodon group by having the opercle almost completely covered laterally by thick layer of skin, the absence of buccal papilla, weak to moderately developed keels on the lateral plates of the body and by the color pattern of its body and fins. Hypostomus basilisko, new species, is distinguished from the remaining species of the H. cochliodon group by the absence of spots on the body, highly developed keels and spoon-shaped teeth. Hypostomus khimaera, new species, is distinguished from the other species of the H. cochliodon group by having a dark tan stripe along the midline of the flank, black spots on the body and/or fins and teeth with mesial cusp and not spoon-shaped.O grupo Hypostomus cochliodon é um clado monofilético com 20 espécies válidas de cascudos neotropicais que estão amplamente distribuídos por toda América do Sul. Recentemente, espécimes identificados como H. cochliodon da localidadetipo e regiões próximas foram examinados e descobriu-se que se tratavam de representantes de mais de uma espécie. Uma redescrição de H. cochliodon é apresentada, com a descrição de duas espécies novas, uma da Serra da Bodoquena e outra de várias localidades da bacia do rio Paraguai. Um lectótipo para H. cochliodon é aqui designado, já que a designação anterior é inválida. Hypostomus cochliodon é diagnosticado de todas as outras espécies do grupo H. cochliodon por possuir opérculo quase completamente coberto lateralmente por uma grossa camada de pele, ausência de papila bucal, placas laterais do corpo com quilhas fracas ou moderadamente desenvolvidas e pelo padrão de coloração de seu corpo e nadadeiras. Hypostomus basilisko, espécie nova, é distinguida das demais espécies do grupo H. cochliodon pela ausência de pintas no corpo, quilhas muito desenvolvidas e dentes em forma de colher. Hypostomus khimaera, espécie nova, é distinguida das outras espécies do grupo H. cochliodon por possuir uma faixa escura ao longo da linha mediana do corpo, pintas pretas no corpo e/ou nadadeiras e dentes com cúspide mesial não em forma de colher.

Range extension of Hypostomus cochliodon Kner, 1854 (Siluriformes: Loricariidae) in Bermejo River, Salta, Argentina

“…As it was reported by Tencatt et al (2014), the coloration pattern is highly variable in this species with some altitude ( m above sea level) recorded for this species, in addition to the rst record for Salta province. e upper Bermejo River basin has rocky bottoms and moderately fast to fast-owing waters that run from west to east through the Andes to the chacoan plain.…”

“…Species of the Hypostomus cochliodon group, along with Panaque Eigenmann & Eigenmann, 1889, are distinctive among fishes by feeding on wood as the major part of the diet (Schaefer and Stewart 1993;Armbruster 2003 Morphometric measurements were taken following Tencatt et al (2014); they were taken with a caliper to nearest 0.01 mm, are straight lines between two points, and expressed as percentage of standard length (SL) and head length (HL).…”

“…After an intensive sampling performed at northwestern Argentina in the Bermejo River basin, the main western tributary to the Paraguay-Paraná system, we collected specimens identified as Hypostomus cochliodon, according to the diagnosis provided by Tencatt et al (2014). Those new records for this basin considerably extend the known distribution range of this species and also represent the first record for H. cochliodon in the Yungas province (sensu Morrone 2014) and the highest According to Tencatt et al (2014), Hypostomus cochli odon can be distinguished from the other species of the H. cochliodon group by the following characters: 1) opercle almost completely covered by a thick layer of skin and exposed region not easily visible; 2) absence of buccal papillae; 3) presence of weak to moderately developed keels on lateral plates; 4) presence of small dark spots closely-set on head and larger, widely spaced spots on trunk, with caudal peduncle generally without spots; 5) caudal-fin lobes evenly colored; 6) bicuspid teeth with a large spoon-shaped mesial cusp and inconspicuous lateral cusp that is generally fused to mesial cusp; 7) absence of a longitudinal dark stripe along midline of flank; and 8) presence of an adipose fin. All these characters are shared by the specimens collected at the Bermejo River basin (Figures 2-4), allowing us to identify them as H. cochliodon.…”

A new species of the Neotropical loricariid Hypostomus cochliodon group (Hypostominae) from the lower Rio Tapajós basin, Brazilian Amazon

“…The greatest diversity of the group occurs in the Amazon basin, with 13 known species (Armbruster, 2003;Armbruster & de Souza, 2005; Hollanda Carvalho et al, 2010;Lilyestrom, 1984;Tencatt et al, 2014;Zawadzki & Hollanda Carvalho, 2014).…”

“…Species of the H. cochliodon group inhabit freshwater ecosystems across both Trans‐ and Cis‐Andean South America, with records in the Río Atrato basin and Lake Maracaibo basin, north‐west of the Andes, and in extensive drainage systems east of the Andes, including the Orinoco, Amazon, Essequibo, Magdalena and Paraguay basins. The greatest diversity of the group occurs in the Amazon basin, with 13 known species (Armbruster, 2003; Armbruster & de Souza, 2005; Hollanda Carvalho et al ., 2010; Lilyestrom, 1984; Tencatt et al ., 2014; Zawadzki & Hollanda Carvalho, 2014).…”