Hypostomus

Jonathan W. Armbruster, Leigh A. Tansey & Nathan K. Lujan, 2007, Hypostomus rhantos (Siluriformes: Loricariidae), a new species from southern Venezuela., Zootaxa 1553, pp. 59-68 : 59-60

[[ Hypostomus ]]

The genus Hypostomus has 138 species currently recognized as valid making it the largest genus in the Loricariidae (suckermouth armored catfishes; Armbruster, 2004). Few of the species are well defined, and a comprehensive review of the genus is lacking. Other than individual species descriptions, the taxonomic reviews that have been done on Hypostomus are limited to geographic reviews (Boeseman, 1968; Reis et al., 1990) or to small monophyletic groups such as the H. unicolor group (Armbruster and Page, 1996; Armbruster, 1998) and the H. cochliodon group (Armbruster, 2003b; Hollanda Carvalho and Weber, 2004).

The type species of Hypostomus is H. plecostomus , a species from the coastal Guyanas (Boeseman, 1968). It is characterized by dentaries angled just greater than 90° (Armbruster, 2004), viliform teeth, and a generalized morphology consisting of a fairly broad, fairly short body, that is mildly dorsoventrally flattened and brown with dark spots (Boeseman, 1968). There are species of similar morphology in lowlands of most major river basins of tropical South America.

Armbruster (2004) recognized very few subdivisions within Hypostomus , recognizing only an H. emarginatus group and an H. cochliodon group. For the purposes of this paper, Hypostomus is recognized in two main groups the H. emarginatus group (as defined in Armbruster, 2004) and the H. plecostomus group (all the other species). The H. plecostomus group additionally has the H. cochliodon subgroup as defined in Armbruster (2003b, 2004), Hollanda Carvalho and Weber (2004), and Armbruster and de Souza (2005). Few species of the H. plecostomus group (excepting species of the H. cochliodon subgroup) have been described from the Orinoco River basin (just H. argus ) and none from the Negro (Weber, 2003, pers. obs.). In addition, there is a species of Hypostomus in the Orinoco that is very similar to H. robinii (described from Trinidad, pers. obs.). Some specimens of a Hypostomus with extremely small spots have been found in the Orinoco River drainage of southern Venezuela, and Armbruster (2004) referred these specimens to H. micromaculatus (a species described from Suriname, Boeseman, 1968). Examination of types of H. micromaculatus reveals that the Venezuelan specimens do not belong to this species, and comparison of the specimens to types or original descriptions of all other species of Hypostomus reveals that the specimens represent a new species.