Bayesian and parsimony phylogeny of Augochlora bees (Hymenoptera: Apoidea) based on morphology: insights for their biogeography and natural history

Abstract

Augochlora Smith, with 127 valid species, is the most widespread genus of Augochlorini bees, ranging from Argentina to southern Canada, including the Caribbean islands. The genus is divided into three subgenera, Augochlora s. str., Oxystoglossella Eickwort, and the fossil Electraugochlora Engel. The extant subgenera were traditionally diagnosed by their nesting substrate, social behavior and morphology. However, accumulating evidence suggests that these features are not reliable for their separation, especially with the discovery of an enigmatic species sharing characteristics from both subgenera. Our objective is to provide a phylogenetic hypothesis to evaluate the monophyly of the extant subgenera and to place a new species, Augochlora (Augochlora) intermedia sp. nov. For this purpose, we compiled 110 unordered characters for 40 species of Augochlora plus seven outgroup species and analyzed under parsimony and Bayesian inference. Topologies were very similar under both frameworks, allowing us to consistently characterize a few major lineages. Our results demonstrate that the extant subgenera correspond to monophyletic groups and the new species is sister group to remaining Augochlora s. str. species. Both subgenera are widespread in the Western Hemisphere, with species groups differing in range and distributional patterns. Our interpretation is that Augochlora arose in South America, subsequently colonizing Mesoamerica, the Caribbean and North America several times. Facultative social behavior can be found in both subgenera and in most lineages, indicating that the exclusive solitary behavior found in Augochlora pura is an exception. Based on morphological clues we interpret that the habit of nesting out of the soil arose once in Augochlora s. str.