279 Paranaella luquei gen. et sp. n. (Monogenea: Microcotylidae), a new parasite of Brazilian catfishes Anna Kohn 1,2 , Maria de Fatima D. Baptista-Farias 1 and Simone Chinicz Cohen 1 1 Laboratório de Helmintos Parasitos de Peixes, Departamento de Helmintologia, Instituto Oswaldo Cruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brasil; 2 Research fellow I-A from “Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq” Key words: Monogenea, Microcotylidae, Paranaella luquei, catfishes, Paraná River, Brazil Abstract. Paranaella, a new microcotyline monotypic genus, is erected to accommodate Paranaella luquei sp. n., parasite of gill filaments from Hypostomus sp., Hypostomus regani (Ihering) and Rhinelepis aspera Spix et Agassiz (Loricariidae) from the Paraná River, Brazil. The new genus is most closely related to Microcotyle Van Beneden et Hesse, 1863, Diplostamenides Unnithan, 1971 and Solostamenides Unnithan, 1971. From Microcotyle it differs mainly by having the genital atrium formed by a muscular ring with a concentric row of numerous elongate and straight spines; from Diplostamenides it can be distinguished by the unarmed and not differentiated cirrus and from Solostamenides it differs by the single vaginal pore and absence of larval hooks. Based on the male terminalia and on general distribution or absence of armature, Unnithan (1971) proposed a systematic partition of Microcotylidae, with 4 subfamilies and 18 genera. Mamaev (1986) presented a taxonomical composition of the Microcotylidae with 8 subfamilies and 39 genera. Despite the large number of microcotylid species reported from other geographical localities, only 15 species in 9 genera have been reported in South America (Kohn and Cohen 1998, Kohn and Paiva 1999), 14 from marine and one from brackish water fishes. During recent studies on the helminth fauna of fishes from the freshwater reservoir of the hydroelectric power station of Itaipu, Paraná River, a new species of a new genus of Microcotylinae was found on the gills of two different genera of catfishes. MATERIALS AND METHODS Fishes from the reservoir of Itaipu Hydroelectric Power Station were collected with nets and kept alive until examination. One Hypostomus regani (Ihering) collected in 1992 and seven in 1995 were identified by Dr. Okada from “Universidade de Maringá, Paraná”; seven specimens of Hypostomus sp. and eighteen of Rhinelepis aspera Spix et Agassiz examined in 1999 were identified by Dr. Ferreira de Moraes Junior and Dr. Nunan from “Museu Nacional, Rio de Janeiro”. The methodologies used for light and scanning electron microscopies were described in Kohn and Cohen (1996) and in Kohn et al. (1994). Light micrographs were made using a scanning laser confocal microscope Zeiss LMS 410. Measurements were made using a calibrated filar micrometer and are given in micrometers unless otherwise stated, as the range with the mean in parentheses. Holotype, paratypes and voucher specimens are deposited in the Helminthological Collection of the Oswaldo Cruz Institute, Rio de Janeiro, Brazil (CHIOC) and one paratype in the Institute of Parasitology, Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic (ASCR). RESULTS Family M i c r o c o t y l i d a e Taschenberg, 1879 Subfamily M i c r o c o t y l i n a e Monticelli, 1892 Paranaella gen. n. Diagnosis Body lanceolate. Haptor subsymmetrical with numerous clamps, arranged into sub-equal rows. Clamps of microcotylid type, similar in shape. Hooks absent. Paired buccal suckers unarmed, with septum. Intestinal crura ramified, co-extensive with vitellaria, extending into haptor. Testes numerous, postovarian. Cirrus not differentiated. Genital atrium a muscular ring with numerous long, straight spines disposed in two levels of a concentric row. Ovary tubular, anteriorly folded back on itself. Eggs with a long polar filament. Vagina single, mid-dorsal, unarmed. Vitellaria may extend into haptor. Parasites of freshwater fishes. T y p e s p e c i e s : Paranaella luquei sp. n. E t y m o l o g y : The generic name refers to the type locality at the Paraná River. Paranaella luquei sp. n. Figs. 1-8 Description: Based on 15 mature whole-mounted worms. Body elongate, 2.7-8.1 mm (5.9 mm) in total length, 0.8-1.9 mm (1.3 mm) in maximum width at level of ovary. Haptor distinguished from body, triangular, lateral margin well developed in its anterior part, Address for correspondence: A. Kohn, Laboratório de Helmintos Parasitos de Peixes, Instituto Oswaldo Cruz, FIOCRUZ, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brasil. Phone: ++21 598 4361; Fax ++21 260 4866; E-mail: annakohn@ioc.fiocruz.br; annakohn@marlin.com.br FOLIA PARASITOLOGICA 47: 279-283, 2000