Collection of Pollen Grains by Centris (Hemisiella) tarsata Smith (Apidae: Centridini): Is C. tarsata an Oligolectic or Polylectic Species? Lia Gonçalves 1 , Cláudia Inês da Silva 2 , and Maria Luisa Tunes Buschini 1, * 1 Departamento de Biologia, Univ. Estadual do Centro-Oeste, Rua Presidente Zacarias 875, CEP: 85010-990, Guarapuava (PR), Brasil 2 Departamento de Biologia, Univ. de São Paulo, Faculdade de Filosofa Ciências e Letras, Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto-SP, Brasil. E-mail:claudiainess@gmail.com (Accepted September 21, 2011) Lia Gonçalves, Cláudia Inês da Silva, and Maria Luisa Tunes Buschini (2012) Collection of pollen grains by Centris (Hemisiella) tarsata Smith (Apidae: Centridini): Is C. tarsata an oligolectic or polylectic species? Zoological Studies 51(2): 195-203. Among pollinator species, bees play a prominent role in maintaining biodiversity because they are responsible, on average, for 80% of angiosperm pollination in tropical regions. The species richness of the bee genus Centris is high in South America. In Brazil, these bees occur in many types of ecosystems. Centris tarsata is an endemic species occurring only in Brazil. No previous studies considered interactions between plants and this bee species in southern Brazil, where it is the most abundant trap-nesting bee. Accordingly, the goals of this study were to investigate plants used by this species for its larval food supply and determine if this bee is polylectic or oligolectic in this region. This work was conducted in the Parque Municipal das Araucárias, Guarapuava (PR), southern Brazil, from Mar. 2002 to Dec. 2003. Samples of pollen were collected from nests of these bees and from fowering plants in grassland and swamp areas where the nests were built. All of the samples were treated with acetolysis to obtain permanent slides. The family Solanaceae was visited most often (71%). Solanum americanum Mill. (28.6%) and Sol. variabile Mart. (42.4%) were the primary pollen sources for C. tarsata in the study area. We found that although C. tarsata visited 20 species of plants, it preferred Solanum species with poricidal anthers and pollen grains with high protein levels. This selective behavior by females of C. tarsata indicates that these bees are oligolectic in their larval provisioning in this region of southern Brazil. http://zoolstud.sinica.edu.tw/Journals/51.2/195.pdf Key words: Centris (Hemisiella) tarsata, Solanum variabile, Solanum americanum, Provision of pollen grains. *To whom correspondence and reprint requests should be addressed. E-mail:liagoncalves22@hotmail.com; isatunes@yahoo.com.br B ees of the family Apidae can fly long distances in tropical forests in search of preferred plant species, thus promoting cross-pollination (Frankie et al. 1983, Roubik 1993). The plant- pollinator relationship is symbiotic and establishes a beneficial relationship between 2 species with different levels of dependency (Boucher et al. 1982, Del-Claro 2004). According to Faegri and Van der Pijl (1979) and Proctor et al. (1996), plant- pollinator interactions are considered to result from natural selection, which produces a wide variety of adaptations in plants, allows the transfer of pollen grains, and increases gene fow within a species. Among pollinator species, bees play an important role in maintaining biodiversity. On average, they are responsible for 80% of angio- sperm pollination in tropical regions (Kevan and Baker 1983, Bawa 1990). The higher effciency of bees as pollinators results from their high numbers compared to other pollinators and from their superior adaptations to complex floral structures. For example, their bodies and mouthparts are adapted to collect and transport resources, such as nectar and pollen, respectively (Kevan and Baker Zoological Studies 51(2): 195-203 (2012) 195