A New Species of Hisonotus (Siluriformes: Loricariidae: Hypoptopomatinae) from the Laguna dos Patos Basin, Southern Brazil

Hisonotus armatus, a new hypoptopomatine species, is described from the Laguna dos Patos basin, Rio Grande do Sul State, southern Brazil. The new species is distinguished from other Hisonotus species by aspects of the morphology of the rostral plate, the arrangement of abdominal plates, and the caudal-fin color pattern.

Hisonotus armatus, nova espécie de hipoptopomatíneo, é descrita do sistema da laguna dos Patos, Rio Grande do Sul, sul do Brasil. A nova espécie se diferencia das demais do gênero Hisonotus pela morfologia da placa rostral, pelo arranjo das placas abdominais, e pelo padrão de colorido da nadadeira caudal.

Figure 1

Hisonotus armatus, holotype, MCP 41323, 44.4 mm SL, female, Brazil, Rio Grande do Sul, Pedro Osório, Arroio Arambaré, about 5 km south of Vila Basílio, on road to Pedro Osório.

Figure 2

Scanning electron microscope images of anterior tip of snout. Hisonotus armatus, MCP 37682, 40.1 mm SL (A, C), showing the snout completely covered by odontodes; and Hisonotus laevior, MAPA 1755, 40.9 mm SL (B, D), showing a stripe devoid of odontodes.

Figure 3

Arrangement of abdominal plates in Hisonotus armatus, female, MCP 25138, 42.5 mm SL. Anterior toward top. Scale bar represents 2 mm.

Figure 4

Geographic distribution of Hisonotus armatus in the Laguna dos Patos basin; T indicates type-locality. 1–Rio Jaguarão, 2–Canal de São Gonçalo, 3–Rio Camaquã, 4–Lago Guaíba, 5–Rio Taquari, and 6–Rio Jacui.

Contributor Notes

Associate Editor: C. J. Ferraris.

¹ Laboratório de Ictiologia, Pontifícia Universidade Católica do Rio Grande do Sul, Av. Ipiranga 6681, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil; E-mail: (TPC) tiagobio2002@yahoo.com.br. Send reprint requests to TPC.

Received: 06 Jun 2007

Accepted: 05 Nov 2007