Abstract
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.
Highlights
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, 2003)
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
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)
Summary
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, 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. The Hypoptopomatinae includes 79 species arranged in 16 genera (Schaefer, 2003), broadly distributed in South American freshwaters. Pseudotocinclus has included only one species, P. tietensis (Ihering, 1907), considered endemic to the headwaters of the upper rio Tietê basin (Britski & Garavello, 1984)
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