Abstract The adult stage of Prebaetodes Lugo-Ortiz & McCafferty is described for the first time based on reared specimens from Venezuela. The adults of the genus can be distinguished from other genera of South American Baetidae by the following combination of characters: paired marginal intercalaries of forewings, anal area rounded and relatively narrow; hind wings absent; male eyes turbinate, contiguous basally and slightly separated dorsally; segment I of forceps without distomedial projection, segment III elongated and uniformly slender. Additionally, a new species, P. meridinensis is described based on nymphs and imagines, and notes on its biology are included. The genus is herein redefined based on variations of characters observed in the new species and the adult generic description. Keywords: Prebaetodes new speciesSouth AmericaVenezuelaAndean streams Acknowledgements We wish to thank Andrew K. Rasmussen, Florida A&M University, for his invaluable assistance in photomicroscopy and scanning images of examined material. We are deeply grateful to Daniela Briceño, Universidad de Los Andes, Mérida, Venezuela, for helping in the collection and rearing of specimens of P. meridinensis. Special thanks to Janice Peters, Florida A&M University, for the loan of some specimens of Baetodes complex and providing some literature for the study. We thank Ralph W. Flowers, Florida A&M University and Cindy Owens, Tallahassee, FL for reading the manuscript and their comments. The research space and equipment provided by the the Center for Water and Air Quality, College of Engineering Sciences Technology and Agriculture to the senior author during her sabbatical at Florida A&M University is deeply appreciated. This research was supported by the Consejo de Desarrollo Cientifico Humanistico y Tecnológico of the Universidad de Los Andes (Proyecto CDCHT-ULA C-960-99-01-C); the Oficina de Intercambio Cientifico de la Universidad de Los Andes; and the Fondo Nacional de Ciencia y Tecnología (FONACIT) de Venezuela.