Frequent Oligolecty Characterizing a Diverse Bee?Plant Community in a Xerophytic Bushland of Subtropical Brazil

Bee-plant relations were studied in the Guaritas region in subtropical Brazil. In this habitat most of the melittophilous plants are herbs, dwarf shrubs and succulents. Bees of about 250 species were recorded foraging on flowers of about 220 plant species. Approximately 30% of the bee species were recognized as oligolectic. a-diversity was particularly high in the bee families Anthophoridae and Halictidae. Evidently, the local apifauna comprises taxa originating from adjacent areas with temperate climate in Uruguay and Argentina. Further biogeographic and environmental conditions probably contributing to the species richness in this up to date little disturbed region are discussed as well as presumed coevolutionary links between the bee and plant partners in the numerous oligolectic foraging strategies observed in this community.