Abstract
The genus Rivudiva Lugo-Ortiz and McCafferty (Ephemeroptera: Baetidae) was established to include two species: Rivudiva minantenna Lugo-Ortiz and McCafferty described from Southern Brazil and Rivudiva trichobasis Lugo-Ortiz and McCafferty described from Southern Brazil and Paraguay. Later, Salles & Nascimento (2009) described the imagos of R. minantenna and transferred Camelobaetidius coveloae (Traver), originally placed in Baetis Leach and Cloeodes venezuelensis (Traver) originally placed in Pseudocloeon Klapalek to Rivudiva.In this work, based on reared material from Presidente Figueiredo, Amazonas state, Brazil, we describe the male imago of R. trichobasis.The descriptions were made in the free program DELTA (DEscription Language for TAxonomy) (Dallwitz, 1980). Nymphs were fixed in 80% ethanol. Euparal (R) was used as the mounting medium for permanent slides.The material examined is housed in the following institutions: Invertebrate Collection of the Instituto Nacional de Pesquisas da Amazonia (INPA), Manaus, Brazil and Invertebrate Collection of the Universidade Federal do Espirito Santo (CEUNES), Sao Mateus, Brazil.
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