Trichomycterus argos

description

Description. Morphometric data of holotype and paratypes are given in Table 1. Body elongate, cylindrical near head and gradually becoming more compressed towards tail. Caudal peduncle strongly compressed. Head wide and depressed. In dorsal view, small specimens with head much wider posteriorly than anteriorly, nearly triangle-shaped; large specimens with rounded head anteriorly. Smaller specimens with straight dorsal head profile, inclined upward from anterior nostril to supraoccipital posterior border; larger specimens with dorsal head profile slightly convex anteriorly, almost horizontal, from eye to supraorbital posterior border; dorsal body profile horizontal or slightly convex from supraoccipital posterior border to dorsal-fin origin, which is somewhat elevated. Dorsal-fin base profile straight and inclined downward, along base of first three rays, continuing straight and horizontal or slightly inclined downward toward end of base, then nearly straight and inclined upward to insertion of caudal fin. Ventral profile of head horizontal or slightly convex; slightly convex or straight towards origin of anal fin; anal-fin base straight and inclined upward (horizontal in small spec

Trichomycterus argos (Teleostei: Siluriformes: Trichomycteridae), a new species from the Doce River Basin, Eastern Brazil

diagnosis

Diagnosis. Trichomycterus argos differs from its congeners, excluding T. alternatus (Eigenmann), T. brasiliensis Lütken, T. brunoi Barbosa & Costa, T. candidus (Miranda Ribeiro), T. claudiae Barbosa & Costa, T. fuliginosus Barbosa & Costa, T. macrotrichopterus Barbosa & Costa, T. maracaya Bockmann & Sazima, T. mariamole Barbosa & Costa, T. mimonha Costa, T. mirissumba Valenciennes, T. novalimensis Barbosa & Costa, T. pantherinus Alencar & Costa, T. potschi Barbosa & Costa, T. rubiginosus Barbosa & Costa, and T. vermiculatus (Eigenmann) by the presence of six branched rays in the pectoral fin, and by having the first pectoral-fin ray prolonged as a filament. Trichomycterus argos is distinguished from T. brasiliensis by the absence of series of spots, as well as absence of confluent spots forming elongated marks or vermiculations (vs. presence of series of large [three times eye-diameter or more] spots dorsolaterally, laterally and ventrolaterally on flank in T. brasiliensis, more clearly visible in small specimens), by a transverse and straight border between the parietosupraoccipital and frontal bones (Fig. 3 a) (vs. oblique and irregular border, in T. brasiliensis; Fig. 3 b) and b

Trichomycterus argos (Teleostei: Siluriformes: Trichomycteridae), a new species from the Doce River Basin, Eastern Brazil

etymology

Etymology. The epithet “ argos ” (Gr.), meaning “ a hundred-eyed monster ” (Brown, 1956: 312), refers to the eye-spotted color pattern of the new species, not forming vermiculations. Biological data. Sampling for study of habitat use was conducted between October 2001 and September 2002 at Serra Nova stream and two of its tributaries, in the same area where the holotype was collected, in a region of the Parque Estadual da Serra do Brigadeiro called Fazenda da Neblina. The local climate presents two well defined seasons, one predominantly mesothermic (Köppen’s “ Cwb ” climate classification) with annual mean temperature of 15 ° C, with possible occurrence of minimum temperatures below 0 ° C. Mean annual precipitation is 1,500 mm, with the dry season extending from July to August. Twenty funnel traps with double entrances were installed monthly in each stream. The height of the water column was measured, and each trap was used for 72 hours / month. The 49 specimens of Trichomycterus collected throughout the study period (SL between 4 and 17 mm) occupied habitats with depth and temperature varying from 13 to 44 cm and from 14 to 19 ° C. A larger number of specimens (15) was collected

Trichomycterus argos (Teleostei: Siluriformes: Trichomycteridae), a new species from the Doce River Basin, Eastern Brazil

materials_examined

Holotype. DZUFMG 103, 95.4 mm SL; Brazil: Minas Gerais State: Araponga municipality, Parque Estadual da Serra do Brigadeiro, Córrego Serra Nova, headwaters of the Rio Casca, right bank tributary of Rio Doce at the limits of Rio Doce and Rio Paraíba do Sul basins, 20 ° 43 ' 19 '' S / 42 ° 28 ' 43 '' W, 1400 m asl; P. S. Santos, 7 October 2001. Paratypes. DZUFMG 0 58, 0 1 ex., 114.7 mm SL; DZUFMG 0 59, 14 ex., 56 – 116.8 mm SL; DZUFMG 0 67, 1 ex., 101 mm SL, C & S; MZUSP 106274, 3 ex., 57.4 – 91.8 mm SL; all collected with holotype.

Trichomycterus argos (Teleostei: Siluriformes: Trichomycteridae), a new species from the Doce River Basin, Eastern Brazil