ABSTRACT

In this chapter we review the published literature on the social behavior of the halictid tribe Augochlorini, and present a generic–level phylogeny. The augochlorine genera show a wide variety of social behaviors ranging from solitary nesting to eusociality, and there is considerable within–species variation. Most species can be characterized as facultatively solitary to semisocial; three genera, Augochlorella, Pereirapis and Augochlora (Oxystoglossella), contain primitively eusocial species. In order to determine the pattern of social evolution in the Augochlorini we performed a phylogenetic analysis using eighty–one morpholo – gical characters derived from Eickwort's (1969b) generic revision of the tribe. These phylogenetic results have some significance for interpreting patterns of social evolution within the Augochlorini. First, although eusociality occurs in three genera, our phylogeny indicates that eusociality arose once within the tribe, in the common ancestor of Augochlorella, Ceratalictus, Pereirapis and Augochlora sensu lato. Second, these results also suggest that eusociality in the Augochlorini arose independently of its origin in the Halictini. Third, the existence of solitary behavior in at least one species of Augochlora sensu stricto can be most parsimoniously explained as a reversal to solitary nesting from a eusocial ancestor. Finally, the sole kleptoparasitic genus in the Augochlorini, Temnosoma, appears closely related to its presumed host, Augochloropsis sensu lato. We discuss the importance of these results for other studies of social evolution and indicate future directions for research on this tribe of bees.