Hisonotus leucofrenatus

Carvalho, Tiago Pinto & Reis, Roberto E., 2011, Taxonomic review of Hisonotus Eigenmann & Eigenmann (Siluriformes: Loricariidae: Hypoptopomatinae) from the laguna dos Patos system, southern Brazil, Neotropical Ichthyology 9 (1), pp. 1-48 : 18-19

Hisonotus leucofrenatus (Miranda Ribeiro, 1908) Figs. 20a and 21a

Otocinclus leucofrenatus Miranda Ribeiro, 1908: 2 [original description, type locality: Rio das Pedras, Ribeira de Iguape River basin, Brazil] .

Microlepidogaster laevior non (Cope, 1884). - Gomes, 1947: 30-32 [misidentified redescription].

Hisonotus leucofrenatus . - Schaefer, 2003: 323 [listed] - Andreata et al., 2006 [karyological description]. -Oyakawa et al., 2007: 94 [comments on ecology and illustration].-Reis & Carvalho, 2007: 84 [listed]. - Ferraris, 2007: 248 [listed]. - Menezes et al., 2007: 214 [illustrated].

Diagnosis. Hisonotus leucofrenatus differs from all congeners except H. armatus , H. leucophrys , and H. notatus by having the combination of anterior margin of the snout completely covered by odontodes, vs. anterior margin of the snout with a narrow or wide odontode-free band; and large plates in the abdominal median series, usually comprising one series of plates between the lateral abdominal plates, vs. abdominal median series of plates small, with several plate series irregularly arranged between the lateral abdominal plates. Hisonotus leucofrenatus differs from H. armatus , H. leucophrys , and H. notatus by an almost completely dark caudal fin ( Fig. 21a) or presence of a faint series of light hyaline spots, forming a vertical bar in the midventral portion ( Fig. 20a), vs. a rounded hyaline blotch in the midventral portion in H. notatus ( Fig. 21b), and one or more series of conspicuous light vertical bars in the ventral portion in H. armatus ( Fig. 21 c-d) and H. leucophrys . Hisonotus leucofrenatus further differs from H. armatus and H. leucophyrs by the color pattern of dorsal surface of the head, which is plain dark to light brown, vs. dorsal surface of the head covered by vermiculate and ovoid white and dark spots. Hisonotus leucofrenatus can be also distinguished from H. leucophyrs by the absence of a conspicuous tuft of odontodes on parieto-supraoccipital tip, vs. presence of a conspicuous tuft of odontodes on parietosupraoccipital tip and by the presence of comparatively narrower light horizontal stripes on posterodorsal portion of head, vs. broader light horizontal stripes on the posterodorsal surface of the head.

Description. A redescription of Hisonotus leucofrenatus is beyond the scope of this paper.

Distribution. Hisonotus leucofrenatus is distributed along the eastern coastal plain of laguna dos Patos in Rio Grande do Sul ( Fig. 22) and is sympatric with H. laevior in this region. Outside the boundaries of the laguna dos Patos system, H. leucofrenatus is distributed in the Brazilian Atlantic coastal drainages of São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul States; from the rio Ribeira de Iguape basin (type locality) to the rio Tramandaí system.

Remarks. Hisonotus leucofrenatus is found in the rio Tramandaí system, where it has been misidentified by Gomes (1947) as Hisonotus laevior in the resurrection and redescription of the latter.Although the three specimens used in the redescription of Gomes (1947) were not examined, extensive material from the same river (rio Maquiné) and other localities in the rio Tramandaí system were examined. Hisonotus laevior is absent in that system, being H. leucofrenatus the only species of Hisonotus in that region. Also noteworthy is the presence of H. leucofrenatus in the laguna dos Patos system. That species has a patchy distribution in that region contrasted with its wider distributions in neighboring basins. Hisonotus leucofrenatus was described from the rio Ribeira de Iguape basin, a Brazilian Atlantic coastal drainage in southern São Paulo State. No difference was found between examined populations from rio Ribeira de Iguape and rio Tramandaí and all can be diagnosed as above. Recently, a karyologycal characterization of H. leucofrenatus byAndreata et al. (2006), revealed no differences between H. leucofrenatus populations along the Atlantic coastal drainages from rio Ribeira de Iguape to rio Itapocú drainage at northeast Santa Catarina, indicating not only the morphological similarity mentioned here, but karyotype homogeneity. Considering the wide range of this species, an accurate review of H. leucofrenatus populations from Brazilian southeastern coastal drainages should be done to determine with certainty whether these populations are a single species.

Material examined. All from Brazil. Laguna dos Patos system: MCN 4640, 1, 29.1 mm SL, Viamão, lagoa Negra at Parque Estadual de Itapuã. MCN 17790, 1 , 33.2 mm SL, lagoa do Casamento at southeast coast of Ilha Grande, Palmares do Sul, 30º24’11”S 50º36’56”W . MCN 18137, 5 , 25.4-28.9 mm SL, Palmares do Sul , lagoa do Casamento at southern margin, 30º29’S 50º35’W . MCP 21373, 1 , 36.4 mm SL, São José do Norte , laguna dos Patos at Barra Falsa, downstream dam, 31º34’19”S 51º27’35”W . MCP 41630, 7 , 26.3 -39.0 mm SL, São José do Norte , laguna dos Patos at Barra Falsa, upstream dam, 31º34’19”S 51º27’35”W . Outside of laguna dos Patos system . INPA 28608 , 10 , 33.6 -44.0 mm SL, São Paulo , rio Tejuco on road to Itapirapuã Paulista . MCP 11540, 60 + 3 c&s, Santa Catarina , rio Cubatão (norte) . MCP 13645, 12 , Rio Grande do Sul , Capão da Canoa, Canal at Vila Cornélios between lagoa Itapeva and lagoa dos Quadros . MCP 14834, 8 , Santa Catarina , Praia Grande, rio Canoas 8 km from Praia Grande on the road to Mãe dos Homens . MCP 20722, 3 , Rio Grande do Sul , creek tributary to rio Maquiné near Maquiné . MCP 21342, 7 , Rio Grande do Sul , canal between lagoa Emboaba and lagoa Emboabinha . MCP 29298, 2 , Rio Grande do Sul , rio Três Forquilhas on Vila Itati . MCP 32217, 31 , Santa Catarina , Jaraguá do Sul , rio Alma tributary of rio Jaraguá . MCP 39094, 4 , 38.3-47.6 mm SL, Paraná , Morretes , rio Marumbi tributary of rio Nhundiaquara, 25º29’S 48º49’W . MZUSP 36565 , 20 , São Paulo , small creek on road from Eldorado to Sete Barras . MZUSP 60220 , 11 , São Paulo , córrego Fria . UFRGS 4986 , 4 , Rio Grande do Sul , arroio Água Parada tributary to rio Maquiné . UFRGS 11526 , 19 , 22.2-30 mm SL, Rio Grande do Sul , Mostardas, lagoa do Bacupari, 30º31’S 50º25’W .