Petilipinnis, A New Genus For Corvina Grunniens Schomburgk, 1843 (Perciformes, Sciaenidae) From The Amazon And Essequibo River Basins And Redescription Of Petilipinnis Grunniens

KEYWORDS: Petilipinnis, freshwater Sciaenidae, Petilipinnis grunniens. INTRODUCTION The Sciaenidae (croakers, drums, pescadilhos, pescadas, and corvinas) is one of the largest perciform families in number of species and distribution, including approximately 78 genera and 287 species worldwide, in coastal and brackish waters of temperate and tropical areas of the world (Chao, 1986). The genera Aplodinotus Rafinesque, Pachypops Gill, Pachyurus Agassiz, Plagioscion Gill, and Boesemania Trewavas are restricted to freshwater.

Aplodinotus occurs in North America; Pachypops, Pachyurus, and Plagioscion in South America, from northern Venezuela to the lowlands of Argentina (Chao, 1978); and Boesemania in Thailand, Vietnam, Cambodia, and Sumatra (Kottelat et al., 1993). Furthermore, Dendrophysa Trewavas, Johnius Bloch and Nibea Jordan & Thompson, from the Indo-Pacific, can occasionally enter freshwater (Kunio Sasaki, personal communication). 1 Laboratório de Ictiologia, Departamento de Biologia, FFCLRP-USP, Av.

Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil. E-mail: licasatti@netsitemail.com.br. Trabalho recebido para publicação em 16.XI.1999 e aceito em 08.II.2001.

The genus Corvina was proposed by Cuvier (1829) and the type species, C. nigra, was subsequently designed by Gill (1861). According to Trewavas (1966), Corvina is a pre-occupied name in Aves, and moreover is a synonym of Sciaena Linnaeus, 1758. Since Corvina is an invalid name in the zoological literature, Corvina grunniens Schomburgk cannot presently be placed in any valid genus.

Notwithstanding this, the diagnosable external character (the presence of one anal spine) and the locality (Essequibo and Amazon River basins), among other characters pointed out in the discussion, show that this species cannot be assigned to any other genus in the Sciaenidae. A new genus, Petilipinnis, is here proposed for Corvina grunniens with a redescription of Petilipinnis grunniens (Schomburgk). METHODS Counts and measurements were taken with calipers with 0,1 mm of resolution and follow Hubbs & Lagler (1958); lateral-line scales counts include the perforated scales to the hypural joint.

Subunits of body are expressed as proportions of standard length (SL), except the anal fin spine length; the anal fin spine length and subunits of the cephalic region are expressed as proportions of head length (HD). One specimen was cleared and stained according the method proposed by Taylor & Van Dyke (1985), and compared with cleared and stained specimens of Pachypops and Pachyurus. The list of the material examined comprises the locality, including the country, state or department, river and complement, institutional number, number of specimens, in parentheses the standard length in mm, collection date and collector.

The examined specimens are deposited in the following institutions: AMNH, American Museum of Natural History; ANSP, Academy of Natural Sciences of Philadelphia; FMNH, Field Museum of Natural History; MZUSP, Museu de Zoologia da Universidade de São Paulo; and INPA, Instituto Nacional de Pesquisas da Amazônia.