Trichomycterus puriventris (Teleostei: Siluriformes: Trichomycteridae), a new species of catfish from the rio Paraíba do Sul basin, southeastern Brazil

Trichomycterus puriventris, new species is described from the upper Paraíba do Sul river basin, southeastern Brazil. It dif­ fers from all species of the genus by the unique colour pattern consisting of dark pigmentation concentrated along and above midline of flank, but absent below midline. The new species is similar to T. alternatus, T. caudofasciatus, T. longibarbatus, and T. pantherinus by all possessing a long pectoral-fin filament. The new species differs from the above species by the pres­ ence of anteriormost section of infraorbital canal, number of pleural ribs, pelvic-fin insertion, dorsal and anal-fins origin, size of nasal barbel, depth and width of the body, and length of the head.


Introduction
Trichomycterus Valenciennes comprises small sized catfishes (about 50 -150 mm SL), constituting the most species-rich genus of the Neotropical Tri chomycteridae (alencar & costa, 2006), with over140 species, distributed mainly in mountain rivers of South America and southern Middle America (Ferraris, 2007).Species of this genus have a remarkable ability to climb waterfalls, resisting strong currents (BarBosa & costa, 2010b), probably due to the presence of opercular and interopercular bone plates, filled with numerous odontodes and linked by a robust ligament.Despite its wide geographic range, most species show a limited distribution, usually endemic to a single small stream (eigenmann, 1918;costa, 1992;BarBosa & costa, 2003a;lima & costa, 2008;sarmento-soares et al., 2011).Trichomycterus has been intensely inves tigated in recent years, with many species being de scribed (e.g., BarBosa & costa, 2010a, b;BarBosa & costa, 2011;BarBosa & costa, 2012;Fernandez & Vari, 2009;Ferrer & malaBarBa, 2011;sarmetosoares et al, 2011).In contrast to other genera of the Trichomycterinae, Trichomycterus is not diagnosable by unique apomorphic features, possibly constituting an artificial assemblage of species (costa, 1992; de Pinna, 1998;BarBosa & costa, 2010b).A high con centration of species has been recorded for southeast ern Brazil, with several being described for the São Francisco, Paraíba do Sul and Paraná river basins, as well as smaller adjacent coastal basins (alencar & costa, 2004;BarBosa & costa, 2003a;BarBosa & costa, 2008;BarBosa & costa, 2010a,b;lima & costa, 2008).The new species herein described was collected in a tributary of the rio Paraíba do Sul ba sin, and seems to be closely related to T. alternatus (eigenmann, 1918) BarBosa & costa (2003b).Measurements are presented as percentages of standard length (SL), except for subunits of head, which are presented as percentage of head length (HL).Counts of procurrent caudal-fin rays, vertebrae, branchiostegal rays, teeth and odontodes were made only in cleared and stained specimens (c&s) prepared according to taylor & Van dyke (1985).The method for species delimitation follows the methodology pro posed by daVis & nixon (1992) formally known as population aggregation analysis (PAA), in which spe cies are delimited on the basis of unique combination of non-overlapping character states.Material of the new species is deposited in Instituto de Biologia da Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro.Comparative material is listed in BarBosa & costa (2008) and BarBosa & costa (2010a); com parisons also included x-rays images of T. alternatus deposited in the Field Museum of Natural History (FMHN 58082) Trichomycterus puriventris n. sp.

Description
Morphometric data for holotype and paratypes given in Table I.Body moderately deep, subcylindrical on anterior portion, compressed on caudal peduncle.Dorsal profile slightly convex between snout and end of dorsal-fin base, straight to slightly convex on caudal peduncle.Ventral profile straight to slightly convex between lower jaw and end of anal-fin base, straight on caudal peduncle.Greatest body depth in vertical immediately in front of pelvic-fin origin.Skin papillae minute.Urogenital papilla spherical, in ver tical through anterior third of dorsal-fin base.Dorsal and anal fins approximately triangular.Dorsal-fin origin in vertical between centrum of 19th and 21st vertebra.Anal-fin origin in vertical between base of dorsal fin ray 8 and 10 and through centrum of 23rd or 24th vertebra.Pectoral fin about triangular, lateral and posterior edges slightly convex.First pectoral-fin Vertebrate Zoology n 62 (2) 2012 5; caudal-fin principal rays 13, dorsal procurrent rays 16 -19, ventral procurrent rays 14 -16.Total vertebrae 36 -38; pleural ribs 13 -14.Upper hypural plates sep arated, both approximately equal in width.
Head subtriangular in dorsal view.Maxilla slight ly longer than premaxilla.Teeth cylindrical, slight ly pointed.Tip of nasal barbel reaching middle of pectoral-fin base.Tip of maxillary barbel exceeding ray terminating in long filament, about 50 -75 % of pectoral-fin length.Pelvic fin shorter than anal fin, covering urogenital pore, tip not reaching anal fin, in vertical through base of first branched dorsal-fin ray; pelvic-fin bases separated by interspace; pelvic-fin insertion in vertical through centrum of 17th or 18th vertebra.Caudal fin truncate.Dorsal-fin rays 11 -13; anal-fin rays 9 -11; pectoral-fin rays 8; pelvic-fin rays   todes light yellow; barbels dark grey.Iris light yellow.Dorsal fin pale yellow with small dark brown spots on basal portion.Caudal fin pale orange with small dark brown spots on basal portion.Anal and pelvic fins pale yellow.Pectoral fin yellow, with basal region of fin and distal portion of first ray dark brown (Fig. 1, 2, 3).

Distribution
Tributaries of the upper rio Santíssimo, rio Grande drainage, rio Paraíba do Sul basin, Serra do Barracão, southeastern Brazil.

Habitat notes
The rio Santíssimo at the type locality of T. puri ventris is a fast running water stream, with about 2 m wide and 1 m deep, and sandy bottom (Fig. 4).The water was pale brown and turbid.This species was also collected in Córrego do Leitão (Fig. 5), a clear water stream with rocky bottom.At the exact point of capture, just above a waterfall, the stream was shallow (about 20 -40 cm deep) and reached high current velocities (not meas ured).In both localities all specimens were found un der marginal vegetation, and no specimen was seen swimming at daylight, suggesting that T. puriventris is a nocturnal or crepuscular species.

Etymology
From the Latin purus (pure) and ventris (venter), re ferring to the absence of dark pigmentation below lat eral midline of body.
Colouration.Side of body pale brown above, yellow ish white below lateral midline; longitudinal row of dark purplish brown to black spots on lateral midline, often coalesced to form lateral stripe; row of brown spots along dorsal midline and another similar row of darker spots between dorsal and lateral midlines, some times forming stripes; no spots below lateral midline, but sometimes inconspicuous dots; venter white.Head dark brown on dorsal, white on ventral surface; sub orbital region light brown, preopercular region dark brown; opercular and interopercular patches of odon  costa, 2003; and T. vermiculatus (eigenmann, 1918)], based on an unique placement of odontodes on the opercular plate, which exhibits a diagonal arrange ment.Another species complex is herein proposed on the basis of the presence of a long pectoral-fin filament (costa, 1992)   costa, 2004).Trichomycterus puriventris is a member of the latter group being easily distinguished from all other congeners from southeastern Brazil by its dark pigmentation concentrated along and above midline of flank, but absent below midline (vs.dark pigmentation extending over the ventral region of flank).
endemic to the rio Doce basin, T. caudofasciatus alencar & costa, 2004 from the rio Itabapoana basin, T. longibarbatus costa, 1992 from the rio Reis Magos basin, and T. pantherinus alencar & costa, 2004 from the rio Santa Maria da Vitória basin, southeastern Brazil.