Phylogenetic Relationships and Classification of the Major Lineages of Apoidea (Hymenoptera), with Emphasis on the Crabronid Wasps

Abstract

The superfamily Apoidea is one of the three major groups of Hymenoptera Aculeata, being composed of the sphecoid wasps, the bees, and the Heterogynaidae, a small and poorly known group of wasps. The phylogenetic relationships among the major lineages of apoids were investigated using 130 characters from the morphology of the adult insects, six from larval morphology, and three characters from adult behavior. These 139 characters were analyzed under three parsimony methods: equal weighting, implied weighting, and successive weighting. Different phylogenetic hypotheses were produced by each method (55 trees under equal weighting, four trees under implied weighting, and one tree under successive weighting, for analyses including all 54 exemplar taxa). The results from implied weighting are favored over those of the other two methods and are used to propose a higher level classification for the Apoidea. Heterogynaidae and Ampulicidae constitute the most basal apoid clades; however, the position of Heterogynaidae remains ambiguous: in three implied weighting-trees, it comes out as the sister group of Ampulicidae and in the fourth as the sister group of the remaining Apoidea, ecluding Ampulicidae. The remaining families recognized and their relationships are: [Sphecidae (sensu stricto) + [Apidae (sensu lato) + Crabronidae]]. Only five subfamilies of Crabronidae are recognized: Astatinae, with the tribes Astatini, Eremiasphecini and Ammoplanini; Bembicinae; Crabroninae (including the genera Dinetus, Laphyragogus, Mellinus and Xenophex); Pemphredoninae, with the tribes Psenini (including the genera Obontosphex and Entomosericus) and Pemphredonini; and the Philanthinae.