Pseudotocinclus parahybae, Takako & Oliveira & Oyakawa, 2005

Takako, Adriana Kazue, Oliveira, Claudio & Oyakawa, Osvaldo Takeshi, 2005, Revision of the genus Pseudotocinclus (Siluriformes: Loricariidae: Hypoptopomatinae), with descriptions of two new species, Neotropical Ichthyology 3 (4), pp. 499-508 : 503-504

Pseudotocinclus parahybae , new species Fig. 3

Pseudotocinclus tietensis (not of Ihering, 1907). - Bizerril, 1999: 243 (citation of Siluriformes species of Paraíba do Sul basin). - Bizerril & Lima, 2000:109 (reference, distribution).

Holotype. MZUSP 49122 , female, 62.9 mm SL, Brazil, São Paulo, a tributary of the ribeirão Grande, Fazenda São Sebastião do Ribeirão Grande, rio Paraíba do Sul basin, approx. 22 o 46’S, 45 o 27’W, Pindamonhangaba, C. E. E. Santo, 12 Aug 1995.

Paratypes. MZUSP 47581 , 1 c&s, 62.0 mm SL, same locality of the holotype; O . T. Oyakawa & C. Moreira, 31 Mar 1994 . MZUSP 83611 , female, 66.4 mm SL, same locality as holotype, C. Oliveira et al., 15 Feb 2001 .

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 ).

Description. Morphometric and meristic data given in Table 1; examined specimens 62.0- 66.4 mm 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 scapular bridge; convex from this point to origin of anal fin, and straight from this point to caudal-fin origin. Head plates with small odontodes and comparatively smooth; median region of snout with low crest that finishes between nares; another low crest on either side of snout that continues in 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. Parieto-supraoccipital crests broader than compound pterotic ones. Posteriorly, parieto-supraoccipital bordered by three to four large plates. Interorbital region flattened. Anterior orbit margin positioned approximately midway between snout tip and pterotic posterior process; distance between ventral orbit margin and ventral surface of head approximately twice as long as orbit length. Snout tip usually covered with small platelets, which have odontodes; narrow area of upper lip near tip of snout, usually with platelets with odontodes. Length of maxillary barbel comparatively smaller than in P. tietensis . Frontal contacting anterior margin of compound pterotic isolating sphenotic from orbit.As consequence, infraorbital canals of cephalic laterosensory system enter infraorbital series via frontal compound pterotic junction. Infraorbital 4 greatly expanded ventrally and contacting preopercle. Mid-dorsal series of plates interrupted, only five plates counting from dorsal-fin origin. Plates of median series dorsally expanded and touching dorsal series of plates. Plates in median (lateral) series with lateral line system pore; third lateral line plate large and nearly completely covering expanded distal tip of rib on sixth centrum. First two canal plates reduced in size; first five plates of midventral series comparatively larger; inferior tip of first plate surpassing tip of coracoid ventrolateral process. Fifth plate touching external side of basipterygium and totally covering lateropterygium; unplated area above pelvic fin comparatively smaller; first three plates of ventral series comparatively larger, and totally covering basipterygium posterior process. Coracoid with only small ventrolateral portion exposed and covered with odontodes implanted directly on bone. Abdomen entirely covered with comparatively large platelets contacting one another, leaving no naked area of skin exposed; region between pelvic-fin and urogenital pore naked. Dorsalfin origin situated slightly posterior to vertical line through pelvic-fin origin; posterior margin of dorsal fin straight. When depressed, tip of dorsal-fin unbranched ray reaching vertical line through origin of third ray of anal-fin ray; first dorsal-fin 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. 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.

Color in alcohol. Light brown ground coloration on dorsal and lateral region of body; ventral region of head and belly grayish with numerous dark-brown melanophores distributed randomly. One comparatively broad dark brown midlateral stripe extending from snout to end of caudal peduncle; stripe more conspicuous anteriorly, becoming progressively faded on caudal peduncle. Three, sometimes indistinct, transverse, dark-brown bands on dorsal region of body coalesced with midlateral stripe, first just behind dorsal-fin base, second in middle of caudal peduncle, and last at end of caudal peduncle. Unbranched and branched caudal-fin rays and interradial membranes uniformly dark-brown ground coloration with numerous small melanophores; unbranched rays of other fins with three to five dark brown bands; branched rays with bands of melanophores irregularly arranged; interradial membranes hyaline.

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 .

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.

Figures

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.

Fig. 1. Southern part of São Paulo, Brazil, showing the geographic distribution of P. tietensis (squares), P. juquiae (triangles), and P. parahybae (circle). Some symbols represent more than one lot or locality. Open symbols = type locality. The precise type locality of P. tietensis is not known. 1- rio Paraíba do Sul basin; 2 - rio Tietê basin; 3 - rio Ribeira de Iguape basin.