A New Species of Hisonotus (Siluriformes, Loricariidae) of the Upper Río Uruguay Basin

Abstract

A new species of the hypoptopomatine genus Hisonotus (Loricariidae) is described from a small tributary of the upper río Uruguay basin near the border between Uruguay and Brazil. The new species can be distinguished from all other congeners by the following combination of characters: (1) presence of serrae along distal two thirds of posterior margin of pectoral-fin spine (versus serrae absent, posterior margin smooth); (2) odontodes along anterior margin of snout biserially arranged, dorsad and ventrad series separated by narrow odontode-free area covered by pad of soft tissue; (3) caudal peduncle short (27-34% SL, versus Ͼ 34% SL) and deep (13-15 % SL, versus Ͻ 13% SL); (4) eye large (15-19% HL, versus Ͻ 13% HL); and (5) caudal-fin pigmentation, when well defined, dark brown with a pair of whitish blotches on upper and lower lobes. The significance of the distribution of the new species is discussed relative to the degree of endemism of other fish groups in the Uruguay basin. RESUMENUna nueva especie de Hypoptopomatinae del género Hisonotus (Loricariidae) es descripta para un pequeño tributario del río Uruguay superior, cerca del límite entre Uruguay y Brasil. La nueva especie puede distinguirse de todas las otras especies nominales del género por la siguiente combinación de caracteres: (1) presencia de sierra a lo largo del margen posterior de los dos tercios distales de la espina pectoral (versus margen posterior liso), (2) odontodes del margen anterior del hocico ordenados biserialmente, las series dorsal y ventral separadas por una banda angosta libre de odontodes, cubierta por tejido blando; (3) pedúnculo caudal 2 NO. 3333 AMERICAN MUSEUM NOVITATES corto (27-34 % LE, versus usualmente Ͼ 34) y alto (13-15 % LE, versus usualmente Ͻ 13); (4) ojo grande (15-19 % in HL, versus usualmente Ͻ 13), y (5) patrón de coloración de la aleta caudal, cuando se encuentra bien definido, marrón oscuro, con un par de manchas blanquecinas sobre los lóbulos superior e inferior de la aleta. La distribución geográfica de la nueva especie es discutida en relación al grado de endemismo registrado en otros grupos de peces de la cuenca del río Uruguay.

Descriptions of five new species of the Neotropical cichlid genus Gymnogeophagus Miranda Ribeiro, 1918 (Teleostei: Cichliformes) from the rio Uruguay drainage

“…The rio Uruguay harbors an extraordinary richness and endemism of several fish groups such as Australoheros, Crenicichla, Cyanocharax, Hisonotus, Hypostomus, Loricariichthys and Rineloricaria (Ričan & Kullander, 2008;Lucena & Kullander, 1992;Malabarba & Weitzman, 2003;Aquino et al, 2001;Reis et al, 1990;Reis & Pereira, 2000;Ghazzi, 2008, respectively). This high richness and degree of endemism is also seen in Gymnogeophagus, with 10 of the 16 extant species of the genus occurring in the Uruguay river basin.…”

Size matters: diversity in swimbladders and Weberian ossicles affects hearing in catfishes

“…The structures of the Weberian apparatus and the morphology of the swimbladder in catfishes have been described by several authors since the late 19th century (Sagemehl, 1885;Bridge and Haddon, 1889;Bridge and Haddon, 1892;Bridge and Haddon, 1893;Sörensen, 1895;Chranilov, 1929;Alexander, 1964;Alexander, 1965;Mahajan, 1967;Chardon, 1968;Schaefer, 1987;Aquino and Miquelarena, 2001;Chardon et al, 2003). Our morphological findings that free bladders are larger than encapsulated ones and are accompanied by more ossicles are consistent with most of their observations.…”

Redescription of the endangered hypoptopomatine catfish Parotocinclus spilurus (Fowler, 1941) (Siluriformes: Loricariidae) from the upper rio Jaguaribe basin, northeastern Brazil

“…3). Ontogenetic shape changes were already observed in loricariids, including hypoptopomatine catfishes (Aquino & Miquelarena, 2001;Rosa et al, 2014) and must be related to allometric development of bones, muscles and plates structures (Geerinckx et al, 2008(Geerinckx et al, , 2009.…”