A new species of the catfish genus Trichomycterus ( Teleostei : Siluriformes : Trichomycteridae ) from the rio Paraná basin , southeastern Brazil

A new species of the catfish genus Trichomycterus is described from tributaries of the upper rio Grande, rio Paraná basin, southeastern Brazil. Trichomycterus pirabitira new species is diagnosed by the morphology of the metapterygoid and the caudal fin, and number of vertebrae, branchiostegal rays and interopercular odontodes, relative position of the dorsal, anal, and pelvic fins, head length, and body width. The new species seems to be closely related to the species of the T. brasiliensis complex by having the oblique arrangement of opercular odontodes described for the group.


Introduction
The catfish family Trichomycteridae is a monophyletic group of freshwater fishes, currently including over 250 valid species (EschmEyEr & Fong, 2012).The family is extensively distributed throughout almost all the major river drainages of the Neotropics, from Costa Rica to Patagonia, occurring in practically all types of freshwater habitats, from inundated lowland forest to high-elevation streams of the Andes (dE Pinna, 1998).Despite this wide distribution, taxa of the family have not been recorded to the rio Parnaiba basin, northeastern Brazil, the only break of this broad distribution (dE Pinna & Wosiacki, 2003;BarBosa & costa, 2011).
Supraorbital canal with three pores; first pore in transverse line through anterior nostril, second in trans verse line just posterior to posterior nostril, third in trans verse line just posterior to orbit; third pore appro xi mately equidistant to symmetrical pore and orbit.Infraorbital canal with four pores; first pore in transverse line through anterior nostril, second in transverse line just anterior to posterior nostril, third and fourth posterior to orbit.Preopercular canal with one pore, in vertical through anterior margin of opercular 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 analfin base, straight on caudal peduncle.Greatest body depth in vertical immediately in front of pelvic-fin origin.Skin papillae minute.Urogenital papilla conical, in vertical through anterior third of dorsal-fin base.Dorsal and anal fins approximately triangular.Dorsal-fin origin in vertical through centrum of 20 th or 21 st vertebra.Anal-fin origin in vertical just posterior to midlength of dorsal-fin base and through centrum of 24 th or 25 th vertebra.Pectoral fin about triangular, lateral and posterior edges slightly convex.First pectoral-fin ray terminating in short filament, about 15% of pectoral-fin length.Pelvic fin shorter than anal  per rio Grande, rio Paraná basin, southeastern Brazil: rio Cuiabá, and a small river without name (Fig. 3).Both streams were clearwater and ran modera tely between rocks.The substrate was muddy with submerged litter, where a great number of individuals were found.Trichomycterus candidus (miranda riBEiro, 1949) also dwells the rio Cuiabá, (BarBosa & costa, 2003b;miranda riBEiro, 1949), but the two species were not collected together.Whereas T. pirabitira was found on the uppermost part of the stream, T. candidus was collected a few kilometers away.
Etymology.Pirabitira, from the Tupi, is a contraction of: pira, meaning fish, and ybytyra, meaning mountain.This name is a reference to the peculiar habit of species of the genus Trichomycterus, which usually inhabit mountainous regions.
Discussion.Trichomycterus is a diversified and complex taxon, with many species described and numerous others being collected in several headwater streams of the Neotropics.One of the great tools to the knowledge of the Trichomycterus taxonomy has been the close relationship between some species of the genus, suggesting that they constitute complexes of related species.BarBosa & costa (2010a) recently established the T. brasiliensis complex based on the presence of a unique arrangement of opercular odontodes, disposed obliquely.This group consists of thirteen species distributed through the upper rio São Francisco, Paraíba do Sul, and Paraná basins, as well as, small coastal river basins in southeastern Brazil (BarBosa & costa, 2010a).Among the four species of Tri chomycterus currently recorded for the upper rio Paraná basin, T. candidus, T. paolence (EigEnmann, 1918), T. ma racaya, and T. pauciradiatus alEncar & costa, 2006(alEncar & costa, 2006;BarBosa & costa, 2003b;2010a;Bockmann & sazima, 2004;EigEn mann, 1918), patch of odontodes.Lateral line of body short, with three pores, posteriormost pore in vertical just posterior to pectoral-fin base.
Colouration in life.Side of body and head light yellow, with a pinky colouration on ventro-lateral region.Brown dots coalesced to form vermiculate pattern; coalesced dots forming two narrow stripes, sometimes intermittent, along lateral midline; tiny dots form narrow stripe on ventrolateral region of flank body; a light yellow stripe above and below lateral midline started on pectoral fin to dorsal-fin base.Pinky colouration on ventro-lateral region, light yellow stripes above and below lateral midline cannot be viewed at preserved specimens, but sometimes tiny dots on whole region below lateral midline are present.Dorsum and head brown, with coalesced tiny scattered dots; nasal barbel light brown on base, maxillary and rictal barbels yellow.Venter yellow, without dots.Iris dark grey.Dorsal fin hyaline, with yellow bases and brown dots scattered; anal fin hyaline, with yellow bases; caudal fin yellow on base, with brown dots scattered, light brown on extremity; tiny transverse reddish stripe on caudalfin base, absent at preserved specimens; pectoral and pelvic fins hyaline with light yellow bases.
Distribution and habitat notes.Trichomycterus pira bitira is known from two streams, tributaries of the up-  only T. maracaya belongs to T. bra siliensis complex.Therefore, T. pirabitira is the se cond species of this complex assigned to the upper rio Paraná basin, which may suggest that other new spe cies can be found in the area.