Revision of the genus Pseudotocinclus ( Siluriformes : Loricariidae : Hypoptopomatinae ) , with descriptions of two new species

The genus Pseudotocinclus is revised and two new species are described: Pseudotocinclus juquiae from the Ribeira de Iguape basin and Pseudotocinclus parahybae from the rio Paraíba do Sul basin. The presence of a small naked area on the snout tip distinguishes P. tietensis from P. parahybae and P. juquiae, which have the snout tip covered with small platelets. In addition, P. tietensis has four transverse dark-brown bands on the dorsum coalesced with the midlateral stripe instead of three, as in its congeners. Pseudotocinclus juquiae is distinguished from its congeners by having the orbital ring very prominent and conspicuous, a characteristic not found in P. tietensis or P. parahybae. These three species also differ from their congeners by meristic and morphometric data. Comments on the past connection of Ribeira de Iguape, Paraíba do Sul and upper Tietê basins are presented.


Introduction
Among the 680 or more species of Neotropical Siluriformes of the family Loricariidae, the members of the subfamily Hypoptopomatinae are probably best recognized as belonging to a natural group (Schaefer, 1991(Schaefer, , 2003)).These fishes are small to moderate in size (30-130 mm in standard length) and share a similar overall adult physiognomy, distinctive for the Loricariidae.Most are moderately elongated, a few are strongly depressed, and all share a peculiar morphology of the pectoral-fin skeleton (Schaefer, 1991).The Hypoptopomatinae includes 79 species arranged in 16 genera (Schaefer, 2003), broadly distributed in South American freshwaters.The subfamily is divided into two tribes, Hypoptopomatini and Otothyrini, with the genus Pseudotocinclus being a member of the latter (Schaefer, 1991(Schaefer, , 1998)).Until now, Pseudotocinclus has included only one species, P. tietensis (Ihering, 1907), considered endemic to the headwaters of the upper rio Tietê basin (Britski & Garavello, 1984).
The genus Pseudotocinclus was previously treated as valid (Britski & Garavello, 1984;Schaefer, 1991) and distinguished from other Hypoptopomatinae by having a caudal peduncle that is nearly square in cross section, 26 or more plates along the lateral line, a dorsally positioned eye, an exposed preopercle, an abdomen covered with numerous small platelets, and a naked snout tip.However, in our study, we found that a naked snout tip is found in only one of the species.Like other hypoptopomatines, Pseudotocinclus is primarily herbivorous, more commonly found at or near the upper portion of the water column, in close association with sub-surface structures provided by submerged tree branches, aquatic macrophytes, and terrestrial grass blades growing along creek margins and extending into the water (Schaefer, 1998).
Recent collecting efforts revealed the presence of Pseudotocinclus in tributaries of the Ribeira de Iguape basin (Bizerril & Lima, 2000) and the rio Paraíba do Sul basin.In the present paper, specimens found in the different basins were comparatively analyzed and two new species are described.Counts and measurements follow Boeseman (1968), except that body plate counts and nomenclature follow Schaefer (1997).Specimen size is reported as standard length (SL) expressed in mm.All other measurements are expressed as a percentage of standard length, except for subunits of the head, which are expressed as a percentage of head length.Measurements were taken from the left side of the body whenever possible.Specimens were cleared and double stained for bone and cartilage according to the method of Taylor & Van Dyke (1985).

Specimens
An analysis of the relative growth was performed to identify the existence of morphological differences among the samples of Pseudotocinclus.This analysis was conducted in two stages: first, the allometric relationships among morphometric variables for fishes from each basin were analyzed through a simple regression analysis and logarithmic transformation of the data using the natural basis e (Ln); thereafter, it was verified if these relationships were distinct among the specimens through a covariance analysis (Zar, 1999).An analysis of canonical variable was employed to verify if the specimens of Pseudotocinclus from the basins of the rio Tietê, rio Ribeira de Iguape, and rio Paraíba do Sul belong to different groups, according to their morphological and meristic characteristics (Manly, 1994;Sokal & Rohlf, 1995;Hair et al., 1998;Zar, 1999).All statistical tests were conducted at a significance level of 0.05.

Diagnosis.
The genus Pseudotocinclus can be diagnosed from other Hypoptopomatinae by the presence of a caudal peduncle that is nearly square in cross section from the posterior base of the dorsal fin to the caudal fin, and the following combination of characters: 26 or more plates along the lateral line, a dorsally positioned eye, an exposed preopercle, and an abdomen covered with numerous small platelets.Otocinclus (Microlepidogaster) tietensis Ihering, 1907: 26-27 (type-locality: rio Tietê, São Paulo).-Eigenmann, 1910: 413 (reference).-Gosline, 1945: 100 (reference).-Fowler, 1954: 131 (reference).-Britski, 1969: 200 (catalogue of types).Pseudotocinclus tietensis.-Britski & Garavello, 1984: 226 (redescription).-Burgess, 1989: 439 (list of the species of Loricariidae).- Montoya-Burgos et al., 1998: 363-374 (phylogenetic relationships of the Loricariidae).-Isbrücker, 2001: 32 (reference).-Schaefer, 2003: 327 (check list). Microlepidogaster tietensis. -Miranda Ribeiro, 1911: 89, 422 (copy of description).Pseudotocinclus intermedius Nichols, 1919: 534 (type-locality: Campo Grande, Santo André, São Paulo).-Gosline, 1945: 99 (catalogue).-Fowler, 1954: 134 (reference).-Isbrücker, 1980: 86 (classification   Diagnosis.The presence of a small naked area on the snout tip distinguishes Pseudotocinclus tietensis from P. parahybae and P. juquiae, which have the snout tip covered with small platelets.In addition, Pseudotocinclus tietensis has four transverse dark-brown bands on the dorsal region of the body that coalesce with a midlateral stripe, rather than three in its congeners.Distribution and habitat.This species occurs in many tributaries of the upper Tietê basin (Fig. 1).It is found both in small creeks and medium size rivers such as the rio Paraitinga, a tributary of the rio Tietê, where it lives grazing on semisubmersed overhanging plants; in the rio Grande, a small sized river which drains to the Billings Dam near Vila de Paranapiacaba, Santo André.This species can be found attached to the grass along the river margin and in the middle of the river among rocks and pieces of wood in fast current water.Diagnosis.Distinguished from its congeners by having the frontal in contact with the compound pterotic bone, which excludes the sphenotic from the orbit margin (vs.sphenotic ventral margin contributing to the orbit, contacting the frontal anteriorly, and the compound pterotic posteriorly in P. tietensis and P. juquiae); the abdomen is entirely covered with large platelets that are in each other, leaving no naked skin exposed (vs.abdomen covered with comparatively small and roughly rounded platelets not in contact with each other, leaving naked area of skin exposed); and the region between the pelvic fin and urogenital pore naked (vs.region between pelvic fin and urogenital pore scarcely covered with platelets in P. tietensis and P. juquiae).Distribution and habitat.This species is known only from the type-locality, a tributary of the ribeirão Grande, rio Paraíba do Sul basin (Fig. 1).The type-locality is a medium-size creek, 0.5 m to 1.5 m deep and 5.0 m wide at approximately 800 meters above sea level, on the slope of Serra da Mantiqueira, with very clear, well oxygenated, and fast flowing water, running mainly on stone beds.The following species occur with Pseudotocinclus parahybae at type-locality: Astyanax bimaculatus, Astyanax intermedius, Characidium sp., Rhamdia quelen, Imparfinis minutus, Taunayia bifasciata, Trichomycterus sp., Harttia carvalhoi, and Neoplecostomus microps.

Description. Morphometric and meristic data given in
Etymology.The specific epithet, parahybae, from the Tupi Language [pa´ra] plus [a´yba], "paraíba" in Portuguese, meaning a useless river, or a portion of river too difficult to navigate, and refers to the name of the river basin where this species had been collected.Treated as a noun in apposition.

Pseudotocinclus juquiae, new species
Fig. 4 Pseudotocinclus tietensis (not of Ihering, 1907).-Bizerril & Lima, 2000:109 (reference, distribution).Diagnosis.Distinguished from its congeners by having the orbital ring very prominent and conspicuous (vs.orbital ring not prominent or conspicuous in P. tietensis and P. parahybae); the parieto-supraoccipital and paired compound pterotic bones with a very high crest (vs.parieto-supraoccipital and paired compound pterotic bones with a low crest); the parieto-supraoccipital bordered posteriorly by ten or more small plates (vs.parieto-supraoccipital bordered by three to four large plates in P. parahybae, and three to six large plates in P. tietensis); and the exposed portion of the cleithrum and coracoid comparatively smaller than in P. parahybae and P. tietensis.Distribution and habitat.This species is known from a few localities of the rio Juquiá basin (Fig. 1).The type-locality, Juquitiba, is a small creek 0.5 m to 1.0 m deep, 1.0 m wide at approximately 670 meters above sea level.It is clear, with a slow current, mud, and in some places, sand on the bottom.Marginal vegetation includes a small area of pastures, small trees and shrubs.Etymology.The specific epithet, juquiae, from Tupi Language "yeke´a", "juquia" or "jequiá" in Portuguese, means a small fishing device used in shallow water, and refers to the name of the river basin where this species had been collected.Treated as a noun in apposition.

Discussion
Since the sample of Pseudotocinclus parahybae is composed of only three specimens, regression lines for these specimens were not significant (p>0.05).On the other hand, all other lines obtained in the comparison with P. tietensis and P. juquiae, respectively, were highly significant (p<0.0001).The F test for the linear coefficient showed that P. juquiae had dorsal-fin length, anal-fin length, and ventral-fin length proportionally longer than those found in P. tietensis (Figs.5a-c).On the other hand, P. tietensis had the trunk length proportionally longer than that found in P. juquiae (Fig. 5d).The F test for angular coefficient (parallelism) showed that the specific rate of growth of the dorsal-fin length in relation with the standard length was higher in P. juquiae than that found in P. tietensis, but the specific rate of growth of the trunk length in relation with the standard length was higher in P. tietensis than in P. juquiae.
The results obtained in the analysis of the canonical variables is shown in Fig. 6.Among all morphometric and meristic variables analyzed, the discriminative analysis chose the following in the stepwise process: standard length (SL)/dorsalfin length (DFL), SL/predorsal length (PL), interorbital distance (IOD)/orbital distance (OD), SL/pectoral-fin length (PFL), SL/head depth (HD), SL/head length (HL), SL/ventral-fin length (VFL), SL/snout length (SNL), number of dorsal-fin rays, SL/PAL, number of predorsal plates (PDP), and SL/analfin length (AFL).The other variables investigated were maintained out of the model studied.Three groups were formed -P.juquiae, P. tietensis and P. parahybae -with some overlap among the specimens of P. juquiae and P. tietensis.The first canonical function separated P. parahybae from P. juquiae + P. tietensis.The second canonical function separated P. juquiae and P. tietensis.The canonical analysis shows that the discriminative function 1 is more positively correlated with SL/DFL, SL/PL, SL/PFL, SL/HL, SL/VFL, and SL/AFL and the discriminative function 2 is more positively correlated with SL/DFL, SL/VFL and SL/AFL (correlations higher than 0.20).Thus, P. parahybae is more elongate (larger standard length in relation to the other morphometric variables) when compared with P. tietensis and P. juquiae.
The headwaters of the rio Tietê, rio Paraíba do Sul, and rio Juquiá are located very close to each other near the city of São Paulo.Geological studies suggested that tributaries of the rio Paraíba do Sul basin and of the rio Tietê basin were connected until the Miocene [23 to 8 million years ago (Myr)] when they were separated (Malabarba, 1998).However, considering the modern aspect of the paleoflora and mainly of that from the aquatic paleofauna, some paleontologists suggested that this separation could have been more recent (about 1.5 Myr) (Travassos & Santos, 1955;Duarte & Japiassú, 1971;Brito & Ribeiro, 1975).Geological studies showed that the Ribeira de Iguape extended its drainage south by the capture of some old tributaries of the rio Iguaçu, north of Curitiba, and extended its drainage north by the capture of some old tributaries of the rio Tietê , south of Embu-Guaçu (Almeida & Carneiro, 1998).The capture of the rio Tietê tributaries by the Ribeira de Iguape was not dated (Almeida & Carneiro, 1998).However, some evidence suggests that this capture could have occurred during the Miocene (Melo et al., 1989) or even more recently (Riccomini et al., 1989).The occurrence of different species of Pseudotocinclus in the rio Tietê, rio Paraíba do Sul, and rio Ribeira de Iguape basins corroborate the hypothesis that these three basins were connected in the past.Our preliminary phylogenetic studies indicate that P. parahybae may be the sister-group of P. tietensis examined belong to the following institutions: Museu de Zoologia da Universidade de São Paulo, São Paulo (MZUSP); Laboratório de Biologia e Genética de Peixes, Instituto de Biociências, Universidade Estadual Paulista, Botucatu (LBP); Departamento de Zoologia e Botânica, Universidade Estadual Paulista, São José do Rio Preto (DZSJRP); Laboratório de Ictiologia de Ribeirão Preto, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto (LIRP); Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre (MCP); and Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro (MNRJ).
Color in alcohol.Light brown ground coloration on dorsal and lateral regions of body; head, ventral region, and belly grayish, with numerous dark brown melanophores distributed on surface; dark brown midlateral stripe extending from snout to end of caudal peduncle; stripe almost equal in width in entire length.Four transverse dark-brown bands on dorsal region of body coalesced with midlateral stripe, first at dorsal-fin origin, second just behind dorsal-fin base, third in middle of caudal peduncle, and last near posterior end of caudal peduncle; second band broader than others.Unbranched and branched caudal-fin rays and interradial membranes sometimes showing uniformly dark brown ground coloration as in P. parahybae or showing color pattern similar to that of P. juquiae; unbranched rays of other fins with four to five dark brown bands; branched rays with bands of melanophores irregularly arranged; interradial membranes hyaline.

Fig. 5 .
Fig. 5. Biplots showing the distribution of data obtained for specimens of Pseudotocinclus juquiae (circles) and P. tietensis (squares).plus P. juquiae thus, the capture of the rio Tietê tributaries by the Ribeira de Iguape should be more recent than the separation of the drainages of rio Tietê and rio Paraíba do Sul.

Table 1 ;
examined specimens 37.6-58.1 mm SL; dorsal profile of head convex from snout tip to end of parieto-supraoccipital; dorsal profile of body convex from snout tip to dorsal-fin origin; relatively straight and gently descending from dorsal-fin origin to end of caudal peduncle; ventral profile of body straight from snout tip to scapular bridge; convex more posteriorly to origin of anal-fin, and straight along caudal peduncle.Head plates with small odontodes and comparatively smooth; median region of snout with low crest that terminates between nares; another low crest on either side of snout that continues as low crest on dorsal region of orbit; orbital ring not as prominent or conspicuous as in P. juquiae; parieto-supraoccipital and paired compound pterotic bones with low crest, Sphenotic ventral margin contributing to orbit, and contacting frontal anteriorly and compound pterotic posteriorly; as consequence, infraorbital canals of cephalic laterosensory system enter infraorbital series via sphenotic; infraorbital 4 not expanded ventrally and not in contact with preopercle; space between these two bones filled with several small plates.Mid-dorsal series of plates interrupted, only five plates counting from dorsal-fin origin.Plates of median series expanded dorsally and contacting dorsal series of plates.Plates in median (lateral) series with lateral system pores.Third lateral line plate reduced in size, as two anterior plates, positioned posterior to rib of sixth centrum, and not covering distal tip of rib.First five plates of midventral series comparatively small; inferior tip of first plate contacting tip of coracoid ventrolateral process, and fifth plate only touching lateropterygium tip; unplated area dorsal to pelvic fin comparatively larger; first three plates of ventral series comparatively smaller with tips touching external side of basipterygium posterior process.Coracoid with small ventrolateral portion exposed and covered with odontodes implanted directly on bone.Abdomen covered with relatively large and roughly rounded platelets not in contact with one another, leaving comparatively larger in P. parahybae, but smaller in P. juquiae.Parieto-supraoccipital bordered by three to six plates.Interorbital region flattened.Anterior orbital margin positioned approximately midway between snout tip and pterotic posterior process; distance between ventral orbit margin and ventral surface of head slightly greater than twice orbit length; snout tip with small naked area; narrow area of upper lip near snout tip, with scattered platelets having odontodes; length of maxillary barbel comparatively greater than in P. parahybae.

Table 1 .
Morphometric and meristic data for Pseudotocinclus species.Ratios expressed as percent of standard length, head length or interorbital length.For the meristic values the modal number is presented instead of the mean.Hol -holotype.naked area of skin exposed; region between pelvic fin and urogenital pore scarcely covered with platelets.Dorsal-fin origin situated slightly posterior to vertical line through pelvic-fin origin; posterior margin of dorsal fin straight.When depressed, tip of first unbranched dorsal-fin ray reaching vertical line through origin of third ray of anal-fin; first unbranched dorsal-fin ray width greater than width of second unbranched dorsal-fin ray base.Pectoral-fin unbranched ray covered with small odontodes; its tip extending past pelvic-fin origin; length of first branched pectoral-fin ray equal to unbranched pectoral-fin ray.Distal margin of pelvic fin slightly rounded; its tip almost reaching anal-fin origin.Internal and external anterior processes of pelvic-fin basipterygia fused into compact bone.Basal lamina of first proximal radial of anal fin covered with skin and five or six small irregular plates not visible externally.Hemal spine of vertebra 20 bifurcated; caudal fin with four dorsal procurrent rays and three ventral procurrent rays.

Table 1
Basal lamina of first proximal radial of anal fin greatly expanded, not covered with plates and completely visible externally; visible part being rounded in shape; hemal spines of vertebrae 15-20 non-bifurcated; caudal fin with four dorsal procurrent rays and four ventral procurrent rays.
; examined specimens 62.0-66.4mmSL;dorsal profile of head Fig.3.Pseudotocinclus parahybae, holotype, MZUSP 49122, 62.9 mm SL; tributary of ribeirão Grande, Fazenda São Sebastião do Ribeirão Grande, rio Paraíba do Sul basin, Pindamonhangaba, São Paulo, Brazil.unbranched ray width greater than width of second dorsalfin unbranched ray base; pectoral-fin unbranched ray covered with small odontodes; its tip reaching of pelvic-fin origin; length of first pectoral-fin ray equal to length of pectoralfin unbranched ray.Posterior margin of pelvic fin slightly rounded; its tip reaching anus.Internal and external anterior processes of pelvic-fin basipterygia fused in compact bone.

Table 1 ;
examined specimens 28.5-62.2mm SL; dorsal profile of head convex from snout tip to orbital ring; relatively straight from this point to end of parieto-supraoccipital; dorsal profile of trunk straight and gently descending from parieto-supraoccipital to end of caudal peduncle; ventral profile of body gently straight from snout tip to end of caudal peduncle.All plates of head with small odontodes and comparatively rugged; median region of snout with low crest that finishes between nares, which are surrounded posteriorly by low crest, more noticeable in adults males; another low crest on either side of snout, that continues in very high crest on dorsal region of orbit; orbital ring very prominent and conspicuous; parieto-supraoccipital and paired compound pterotic bones with very high crest.Compound pterotic crest continuing in one keel up to plates located near midway of dorsal-fin base.Pseudotocinclus juquiae, holotype, MZUSP 49333, 57.04 mm SL; first tributary of the rio Juquiá, near ribeirão das Antas on the road from São Lourenço da Serra to Juquitiba, Juquitiba, São Paulo, Brazil.