En t o mo t r o pic a Vol. 18(1): 69-71. Abril 2003 ISSN 1317-5262 © 2003, Sociedad Venezolana de Entomología First report of Americabaetis Kluge (Ephemeroptera: Baetidae) from Rio de Janeiro, Brazil Cesar N. Francischetti 1,3 , Frederico F. Salles 2,3,5 , C.R. Lugo-Ortiz 2 & Elidiomar R. Da-Silva 1,4 1 Laboratório de Insetos Aquáticos, Departamento de Ciências Naturais, Universidade do Rio de Janeiro. Av. Pasteur, 458 / 4 o andar, CEP 22290- 240, Rio de Janeiro, RJ, Brasil. E-mail: labiaqua@unirio.br. 2 Museu de Entomologia, Departamento de Biologia Animal, Universidade Federal de Viçosa, 36571-000, Viçosa, MG, Brasil. 3 Pós-graduação em Entomologia, Universidade Federal de Viçosa. 4 Laboratório de Entomologia, Departamento de Zoologia, Universidade Federal do Rio de Janeiro, Caixa Postal 68044, 21944-970, Rio de Janeiro, RJ, Brasil. 5 Corresponding author. Abstract F RANCISCHETTI C, SALLES F, LUGO-ORTIZ CR, DA-SILVA E. 2003. First report of Americabaetis Kluge (Ephemeroptera: Baetidae) from Rio de Janeiro, Brazil. Entomotropica 18(1):69-71. Americabaetis alphus , A. labiosus , A. longetron, and A. titthion are for the first time reported from Rio de Janeiro State, southeastern Brazil. Additional key words: Americabaetis alphus, Americabaetis labiosus , Americabaetis longetron, Americabaetis titthion, mayflies, neotropics. Resumo F RANCISCHETTI C, SALLES F, LUGO-ORTIZ CR, DA-SILVA E. 2003. Primeiro registro de Americabaetis Kluge (Ephemeroptera: Baetidae) para o Estado do Rio de Janeiro, Brasil. Entomotropica 18(1):69-71. Americabaetis alphus , A. labiosus , A. longetron e A. titthion são pela primeira vez registradas para o Estado do Rio de Janeiro, sudeste do Brasil. Palavras chave adicionais:: Americabaetis alphus, Americabaetis labiosus , Americabaetis longetron, Americabaetis titthion, efêmeras, neotrópico. Kluge (1992) erected Americabaetis (Ephemeroptera: Baetidae) as a subgenus of Baetis Leach for species described from Cuba. Lugo-Ortiz & McCafferty (1994) considered Americabaetis a synonym of Acerpenna Waltz & McCafferty, but subsequently Lugo-Ortiz & McCafferty (1996) elevated it to generic status. Of the twenty currently known species (see Lugo-Ortiz & McCafferty 1996, 1999; Hoffman et al. 1999; Waltz & McCafferty 1999), only five, viz. A. alphus Lugo-Ortiz & McCafferty, A. labiosus Lugo-Ortiz & McCafferty, A. longetron Lugo-Ortiz & McCafferty, A. oldendorffi (Weyenbergh), and A. titthion Lugo-Ortiz & McCafferty have been registered for Brazil, and they are confined to the south-central part of the country (Lugo-Ortiz & McCafferty 1996; Lugo-Ortiz et al. 2002). Recently, larvae of A. alphus , A. labiosus , A. longetron, and A. titthion were collected as part of taxonomic and ecological studies conducted in lotic habitats in Rio de Janeiro (southeastern region of Brazil). The findings are important because they represent the first reports of the four species and of Americabaetis from the state. Material examined Brazil, State of Rio de Janeiro: Itatiaia, Fazenda Aleluia, Rio Campo Belo (22 o 28’S; 44 o 34’W), 14.x.1999, 18 larvae of A. alphus , 8 larvae of A. longetron, C.N. Francischetti col.; Nova Friburgo, Cascatinha, Rio Cascatinha (22 o 20’S; 42 o 34’W), 20.iv.2001, 3 larvae of A. labiosus , 3 larvae of A. titthion, P.C. Ceotto, R.M. Darigo, C.N. Francischetti, F.F. Salles col. The material examined is housed in the entomological collection of Departamento de Zoologia, Instituto de Biologia, Universidade Federal do Rio de Janeiro (Rio de Janeiro, RJ, Brazil). The studied species were identified based on the morphology of the mouthparts (Lugo-Ortiz & McCafferty 1996), assisted, in the case of A. longetron and A. alphus , by the abdominal color pattern (Figures 3-4). The abdominal color patterns of A. titthion and A. labiosus (Figures 1-2) are also illustrated herein, as they were not presented in the original descriptions by