Adult females of Anopheles (Nyssorhynchus) species are difficult to identify in the field using available keys. Entomological studies of vector species and subsequent evaluation of malaria control programs are mainly based on the collection of adult Anopheles, hence a reliable means for identification of adult specimens in the field is required. A dichotomous key based on reared adults with associated immature stages was developed to identify field-collected adult females belonging to the subgenus Nyssorhynchus from a vivax-malaria endemic area in western Venezuela.