HEMIPSILICHTHYS GOBIO (LÜTKEN) (FIG. 4)

Xenomystus gobio Lütken, 1874: 217, pl. 4 (type locality: originally unknown. Restricted herein to the Rio Paraíba do Sul, south-eastern Brazil).

Upsilodus victori Miranda Ribeiro, 1924: 366 [type locality: in Paquequer at Therezopolis, Rio de Janeiro ( Rio Paquequer, a tributary of the Rio Paraíba do Sul)].

Specimens examined: Brazil: Holotype of Xenomystus gobio: ZMUC 76 (121.2 mm SL), male, South America . Lectotype of Upsilodus victori: MNRJ 639 (101.4 mm SL), male, Rio Paquequer, Teresópolis, Rio de Janeiro . Paralectotype of Upsilodus victori: MNRJ 646 (108.3 mm SL) Rio Paquequer, Teresópolis, Rio de Janeiro . Other specimens: MNRJ 13654 (3 + 1 cleared and stained, 60.3–88.7 mm SL) Rio dos Frades, near mouth of Córrego da Chácara, Teresópolis, Rio de Janeiro (22°17′27′S 42°50′48′W), 27 July 1995. MCP 19780 (13, 36.7–123.9 mm SL) and MHNG 2587–31 (4, 45.0– 108.4 mm SL) Arroio Macaquinho, tributary of Rio Paraitinga c. 5 km of Bairro dos Macacos, Silveiras, São Paulo (22°50′47′S 44°50′30′W), 16 January 1997. UFJF 0362 (21, 104.8– 131.8 mm SL) Ribeirão Santana, tributary of Rio Preto, Rio Preto, Minas Gerais, 22 July 1997.

Diagnosis: Hemipsilichthys gobio can be distinguished from H. nimius and H. papillatus by its rectangular or oval-shaped dorsal-fin spinelet (Fig. 3) (vs. V-shaped in H. nimius and absent in H. papillatus), and by the intermediate orbital diameter (12.0–14.7% HL vs. 8.6–11.8% in H. papillatus and 15.3–16.9% in H. nimius).

Description: This species was recently described and illustrated by Pereira & Reis (2002) and the description will not be repeated here. Morphometric data, however, are presented in Table 1 for comparative purposes.

Distribution: Hemipsilichthys gobio is known from several localities in the Rio Paraíba do Sul basin, in the states of São Paulo, Rio de Janeiro, and Minas Gerais, Brazil (Fig. 5).

Ecology: Found in small rivers, with clear water, moderate to strong current, and a substrate of rocks, loose stones and gravel.

Remarks: The type locality of Xenomystus gobio was not cited in the original description. Eigenmann & Eigenmann (1889) described the genus Hemipsilichthys for Xenomystus gobio and included one specimen from the Rio Paraíba do Sul basin. All known specimens collected so far are also from that basin, and it is probable that the holotype is from the Rio Paraíba do Sul drainage. For this reason, we herein restrict its type locality to the Rio Paraíba do Sul.