Re-description of Trichomycterus cubataonis Bizerril , 1994 ( Siluriformes : Trichomycteridae ) from the Cubatão river basin , southern Brazil

Trichomycterus cubataonis, from the Cubatão river, southern Brazil, is re-described and revalidated. It is hypothesized as closely related to T. diabolus, T. itatiayae, T. maculosus and T. nigroautarus based on the presence of a broad metapterygoid, which is wider than deeper. Trichomycterus cubataonis differs from the above four species by the number of pectoral, dorsal, and anal-fins rays, origin of anal fin related to the dorsal-fin base, insertion of pelvic-fin related to the vertebrae, origin of dorsaland anal fins related to the vertebrae, number of dorsal and ventral procurrent rays of caudal fin, number of odontodes of the opercular and interopercular patch, length, depth and width of the head, and eye size. Moreover, T. cubataonis differs from T. zonatus mainly by the insertion of pelvic-fin related to the vertebrae, origin of dorsaland anal fins related to the vertebrae, number of anal fin rays, and the position of the anal fin related to the dorsal-fin base. Therefore, T. cubataonis should be considered a valid species.


Introduction
Trichomycterus Valenciennes, 1832 is a genus of catfishes that are usually found in mountain rivers with highly oxygenated water.This is one of the most diversified gen-era among the neotropical fishes, with over 140 species (costa, 1992;BarBosa & costa, 2003BarBosa & costa, , 2008;;2010a, b;2011;2012a, b;castellanos-Morales, 2008;Fernandez & Vari, 2009;Katz et al, 2013;WosiacKi & Pinna, 2008a, b).The most remarkable feature of its members is the ability to climb rocks in waterfalls, with the help of odontodes present in the operculum and interoperculum.Both the later structures have a special muscular ligament that helps the movement of these bones, assisting the odontodes fixation on the rock (Pinna, 1998).Often it is the only fish genus found in the majority of the rivers headwaters between Costa Rica and Patagonia, including high altitude rivers in the Andes altiplans.However, the highest concentration of species is found in southeastern Brazil (eigenMann 1918;costa 1992;BarBosa & costa, 2010a), the number of species in southern part of the country has increased in the recent years.Nineteen species are known to southern Brazil, among them Trichomycterus nigricans Valenciennes, 1832, the type species of genus (Ferraris, 2007;Ferrer & MalaBarBa, 2013).Trichomycterus cubataonis Bizerril, 1994 was described from the Cubatão river, a southern coastal basin (Bizerril, 1994).Later it was considered to be a junior synonym of Trichomycterus zonatus eigenMann, 1918 (de Pinna & WosiacKi, 2003).Trichomycterus cu bataonis is herein re-described and revalidated.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).Morphometric characters of the holotype were based on examined material (MNRJ 12490), and other measurements were made in topotypes (UFRJ 8736).Counts of procurrent caudal-fin rays, vertebrae, branchiostegal rays, teeth and odontodes were made in cleared and stained specimens (c&s) prepared according to taylor & Van dyKe (1985).Abbreviations for institution are: MNRJ, Museu Nacional, Universidade Federal do Rio de Janeiro; UFRJ, Instituto de Biologia, Universidade Federal do Rio de Janeiro.The method for species de-limitation follows the methodology proposed by daVis & nixon (1992) formally known as population aggregation analysis, which is based on the presence of unique combination of non-overlapping character states to delimit species.Comparative material is listed in BarBosa & costa (2008), BarBosa & costa (2010a), and Katz et al. (2013).

Measurements and counts follow
Trichomycterus cubataonis Bizerril, 1994 Fig. 1 Trichomycterus cubataonis Bizerril, 1994: 29 (original   Description.Morphometric data for holotype and topotypes is given in Table 1.Body subcylindrical on anterior portion, compressed on caudal peduncle.Skin papillae minute.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 vertical through anterior third of dorsal-fin base.Dorsal and anal fins approximately triangular.Dorsal-fin origin in vertical through centrum of 18 th vertebra.Anal-fin origin in vertical after dorsal-fin base and through centrum of 23 th vertebra.Pectoral fin about triangular.First pectoral-fin ray not prolonged as filament.Pelvic fin shorter than anal fin, not covering urogenital pore, tip not reaching anal fin, in vertical just anterior to dorsal-fin origin; pelvic-fin bases separated by interspace, pelvic-fin origin in vertical through centrum of 16 th vertebra.Caudal fin truncate.Dorsal-fin rays 12; anal-fin rays 9; pectoral-fin rays 7; pelvic-fin rays 5; caudal-fin principal rays 13; dorsal procurrent rays 18 -22, ventral procurrent rays 11 -12.Total vertebrae 36 -39; pleural ribs 11 -12.Upper hypural plates separated, dorsal plate smaller than ventral plate.
Head trapezoidal in dorsal view.Snout blunt.Mouth subventral.Maxilla shorter than premaxilla.Teeth conic.Eye at middle of head.Barbels well developed.Tip of nasal, maxillary and rictal barbels reaching anterior edge of opercular patch of odontodes.Tip of maxillary barbel not reaching pectoral-fin base.Seven or eight branchiostegal rays.Interopercular odontodes 21 -29; opercular patch of odontodes with 7 -10; odontodes conical; some opercular odontodes about width to interopercular odontodes; opercular odontodes approximately arranged in circular line.Medial margin of autopalatine slightly to extremely concave; posterior process of autopalatine about equal in length to autopalatine without posterior process.Lacrimal about one third to one quarte supraorbital  length; supraorbital rod-shaped.Metapterygoid moderate in lenght, broad, much wider than deep, without distinct processes; anterodorsal surface of hyomandibula with moderate concavity.Urohyal foramen rounded; distal portion of lateral arm of urohyal laterally pointed.
Supraorbital canal continuous, with three pores; first pore in transverse line through anterior nostril, second in transverse line just posterior to posterior nostril, third supraorbital pore paired, each pore nearer to orbit than to symmetrical pore, in transverse line just posterior to orbit.Infraorbital canal restricted to two pores: first and second pore absent, third and fourth present and posterior to orbit.Preopercular canal with one pore, in vertical through anterior margin of opercular patch of odontodes.Lateral line of body short, with three pores, posterior most pore in vertical just posterior to pectoral-fin base.
Colouration.Side of body and head brown yellowish, with well-defined dark brown blotches along entire body, blotches forming irregular stripe along lateral midline of flank, between pectoral and caudal fins.Dorsal region brown yellowish with large blotches, sometimes fused in irregular and sinuous stripe between head and dorsal fin.Ventral region light brown, without blotches.Nasal, maxillar and rictal barbels light brown.Dorsal, pectoral and anal fins light brown yellowish hyaline on tip.Pelvic-fin transparent.Caudal fin transparent with some small brown dots.In live specimens, body and head golden yellowish with light brown blotches along entire body, well-defined light brown blotches along entire body, blotches forming irregular stripe along lateral midline of flank, between pectoral and caudal fins.Nasal, maxillar and rictal barbels golden yellowish.Dorsal, pectoral and anal fins light orange, with a small diagonal white stripe in the middle.
Distribution.Known from the Cubatão river basin, southern Brazil.Ecological notes.Trichomycterus cubataonis was found in a narrow stream (about 100 cm wide and 50 cm deep) under a bridge.The species was mainly collected along the stream banks, on gravel or litter substrate.Sympatically were in the same habitat the Corydoradinae: Corydoras ehrhardti and Scleromystax barbatus, the Characidae: Astyanax sp., the Loricariidae: Rhineloricaria sp. and the Poeciliidae: Phalloceros sp.

Discussion
Trichomycterus has been the object of many field and taxonomic researches, thanks to that, a great diversity has been described until now.However, little is known about the relationships between the species.A few researchers have created hypotheses of relationships among species of Trichomycterus by grouping them in species complex (e.g.costa 1992; BarBosa & costa, 2003;BarBosa & costa, 2008;BarBosa & costa, 2010a;BocKMann et. al., 2004), but this situation is far from been solved.
A recent checklist of freshwater fishes of South and Central America (Pinna & WoziacK, 2003) listed T. cu bataonis as a junior synonym of T. zonatus, however the evidences leading to the synonymization were not clearly showed.Comparing the morphological data of the topotypes and the holotype of T. cubataonis with the morphological data of the holotype of T. zonatus, it is possible to notice significant differences between the two species.
The pelvic-fin insertion and the dorsal, and anal-fins origin in the T. cubataonis is 16 th , 18 th and 23 th vertebrae centrum respectively (vs. 17
th , 20 th and 22 th in T. zonatus).Moreover, T. cubataonis posses 9 anal-fin rays (vs. 10 in T. zonatus), 18 -22 dorsal procurrent rays (vs.15 in T. zonatus), and anal-fin origin after the dorsal-fin base (vs.7 th ray in T. zonatus).Furthermore, T. zonatus and T. cubataonis are known from two distinct coastal river basins, Ribeira do Iguape and Cubatão river basins respectively, separated by approximately 200 kilometers.These facts corroborate the hypothesis that T. cubataonis should be considered a valid species.BarBosa & costa (2008) described Trichomycterus nigroauratus and redescribed T. itatiayae, considering them closely related for exhibiting a broad metapterygoid, wider than deep.They also considered T. diabolus and T. maculosus to be closely related to the two species referred before for presenting the same kind of structure (BarBosa & costa, 2010b).Trichomycterus cubataonis also present this kind of metapterygoid, broad, wider than deep, thus should be considered closely related to the above four species.Also, the T. cubataonis shares with T. castroi, T. diabolus, T. nigroauratus and T. maculosus a colour pattern consisting in large blotches around the flank.Furthermore BocKMann et al. (2004) considered the Trichomycterus castroi de Pinna, 1992 to be related to T. diabolus by both having a conspicuous unpigmented area on the basal region of the caudal fin.Unfortunately the original description of T. castroi do not provide osteological data, including about the metapterygoid.