Gephyrocharax torresi (Characiformes: Characidae: Stevardiinae), a new species from the río Cascajales basin, río Magdalena system, Colombia

Abstract

A new species of Gephyrocharax is described from the río Cascajales basin, a tributary of the río La Colorada, río Magdalena system, Colombia. The new species is distinguished from its congeners, except G. melanocheir, by the absence of an adipose fin in most specimens and by the possession of a lateral branched pectoral-fin ray in males with a distal fan-shaped structure with minute bony hooks and a dark blotch or a few scattered dark brown chromatophores along its branches. The new species differs from G. melanocheir by the absence of an intense black pigmentation at the base of the anterior five dorsal-fin rays, the number of vertebrae (40-41 vs. 38-39), the frontals contacting each other anterior to the epiphyseal bar in adults (vs. the absence of contact), the posterior margin of the mesethmoid straight in its central portion (vs. strongly concave at this point), the pouch scale of mature males reaching caudal-fin ray 11 or the area between caudal-fin rays 11 and 12 (vs. reaching only to caudal-fin ray 10 or the area between caudal-fin rays 9 and 10), the number of minute terminal branches of the lateral branched pectoral-fin ray of mature males (60-88 vs. 28-54), a longer black lateral stripe along the body in males (reaching to the base of the caudal-fin rays vs. reaching the middle of the length of the caudal peduncle), and the snout length (28.3-31.8% HL vs. 22.2-28.0% HL). The diagnosis of Gephyrocharax is modified to include species with the adipose fin variably present.Una nueva especie del género Gephyrocharax se describe para la cuenca del río Cascajales, tributario del río La Colorada, sistema del río Magdalena, Colombia. La nueva especie se distingue de sus congéneres, excepto G. melanocheir, por la ausencia de aleta adiposa en la mayoría de los individuos y por la presencia del radio ramificado lateral de la aleta pectoral con una estructura distal en forma de abanico, la cual tiene ganchos óseos diminutos y una mancha difusa oscura o unos pocos cromatóforos pardos oscuros a lo largo de sus ramificaciones. La nueva especie difiere de G. melanocheir por la ausencia de una intensa pigmentación negra sobre la base de los cinco radios anteriores de la aleta dorsal, el número de vértebras (40-41 vs. 38-39), los frontales contactando entre sí anteriormente a la barra epifisaria en adultos (vs. la ausencia de contacto), el margen posterior del mesetmoides recto en su porción central (vs. fuertemente cóncavo en este punto), la extensión dorsal de la escama-bolsillo de machos maduros alcanzando el radio caudal 11 o el área entre los radios caudales 11 y 12 (vs. alcanzando el radio caudal 10 o el área entre los radios caudales 9 y 10), el número de ramificaciones terminales diminutas del radio ramificado lateral de la aleta pectoral (60-88 vs. 28-54), la línea negra lateral sobre el cuerpo en machos más alargada (alcanzando la base de los radios de la aleta caudal vs. alcanzando la mitad de la longitud del pedúnculo caudal), y la longitud del hocico (28,3-31,8% LC vs. 22,2-28,0% LC). Modificamos la diagno...

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“…Counts of the pectoral-, pelvic-, and dorsal-fin rays follow Böhlke (1958). Measurements and other counts were taken according to Fink and Weitzman (1974), with the addition of two measurements: anal-fin lobe length, following Menezes and Weitzman (1990), and the distance between dorsal-and pectoral-fin origins, following Vanegas-Ríos, Azpelicueta, Mirande, and Gonzales (2013).…”