Abstract.A new stingless bee species of the genus Nogueirapis Moure (Apinae: Meliponini) is described and figured. Nogueirapis costaricana Ayala & Engel, new species, is distinguished from its congeners, particularly N. mirandula (Cockerell), a species also known from the Pacific forests of Costa Rica. A key to the species of Nogueirapis, based on the worker caste, is provided.1 Estación de Biología Chamela, Instituto de Biología, Universidad Nacional Autónoma de Méxi-co (UNAM), Apartado Postal 21, San Patricio, Jalisco, 48980, México (rayala@ib.unam.mx
INTRODUCTIONThe stingless bees of Costa Rica represent a relatively well known fauna (e.g., Wille & Michener, 1973;Griswold et al., 1995 Griswold et al., , 2006, in no small part due to the efforts of Alvaro Wille (1928-2006 who was particularly focused on the biology and systematics of Meliponini and spent his career researching the regional fauna, among many other fields of scientific inquiry (Monge-Nájera, 2006;Michener, 2007a). Nonetheless, new species continue to be recovered from this area and highlight how ongoing studies into the melittofauna are needed even in seemingly intensively worked regions such as Costa Rica. It is from the discovery and description of new species that we continually refine our understanding of patterns of variation, relationships, and biogeography, and test long-ignored concepts of species (Grimaldi & Engel, 2007;Engel, 2011;Gonzalez et al., 2013).During recent work in the extensive collections of the Instituto Nacional de Biodiversidad (Santo Domingo de Heredia, Costa Rica), the authors discovered specimensNo. 37 of the stingless bee genus Nogueirapis Moure that clearly belonged to a species distinct from those previously known. Nogueirapis may somewhat resemble species of Plebeia Schwarz, but in the former the inner surface of the metatibia has a narrow, bare, shiny, but distinctly not depressed upper margin, whereas this same surface is clearly depressed in the latter. In addition, the corbicula is distinctly larger than that of species of Plebeia, with one or two very large bristles arising from its surface (as in the genus Partamona Schwarz), and the frons and mesoscutum is almost devoid of the relatively long setae so noticeable in Plebeia. Nogueirapis differs from Partamona in the less expansively developed corbicula (large and spoon-shaped in species of Partamona), the presence of abundant yellow markings, the few and mostly curved (not sinuous) large setae of the labial palpi (as is found in various species of Plebeia s.str.), the shining and asetose basal area of the propodeum, and the generally small body size (Wille, 1964(Wille, , 1979. The genus is not diverse, with only three previously described species, and only one of those has hitherto been documented from Costa Rica (Camargo & Pedro, 2007). Wille (1959, 1962) described a species in Early Miocene amber from Mexico, Nogueirapis silacea (Wille), one of only two bee species formally described from the deposits of Chiapas, Mexico (Engel & Michener, 2013;Engel, 201...