The ecology and specialized plant interactions of the South American oil-bees Chalepogenus (Apidae: Tapinotaspidini)

Bees of the South American genus Chalepogenus (Apidae: Tapinotaspidini) are floral-oil specialists, harvesting in at least three different plant families. Although their taxonomy has been partially revised some years ago, their evolutionary relationships, ecology, and ranges are very poorly known. The goal of this work was to start filling that knowledge gap to eventually better understand the drivers of the ecology and evolution of the group. We reviewed and collected data from the literature, and public and museum databases, and evaluated floral choices, bee and host-plant morphological traits for all bee species. Further, using georeferenced observations, we estimated the ranges of the species and their climatic preferences. We could successfully and for the first time delimit the ranges of each species and group, demonstrating that the genus has a structured distribution. Our results show that different taxonomic groups visit almost exclusively different floral families, with some of them visiting Calceolaria (Calceolariaceae), and others Nierembergia (Solanaceae) or Cypella (Iridaceae). Our climatic space results suggest that only one group clearly shows a distinct climatic preference. Our study is the first extensive investigation of the biology of this group, providing fundamental information for understanding the role these biotic and abiotic variables played in the diversification of the genus.