A new fossil family of aculeate wasp sheds light on early evolution of Apoidea (Hymenoptera)

In the present work, we describe a new fossil family of Apoidea supported by phylogenetic analyses involving both fossil and extant groups. †Burmasphecidae fam.n. is based on †Burmasphex Melo & Rosa, a genus described from Burmese amber. We include in this family the monotypic genus †Decasphex Zheng, Zhang & Rasnitsyn also from Burmese amber. Additionally, we describe two new genera and four new species in †Burmasphecidae fam.n.: †Burmasphex mirabilis sp.n.; †Simplisphex gen.n., containing S. scutellatus sp.n. and †S. burmensis sp.n.; and †Callisphex robustus gen. et sp.n. In our phylogenetic study, we extended a pre-existing matrix of morphological data and analysed it under parsimony and Bayesian inference. In the Bayesian inference analyses, the morphological dataset was partitioned under a homoplasy criterion. We postulate the first phylogenetic hypotheses for the placement of †Angarosphecidae based on the type species, †Angarosphex myrmicopterus Rasnitsyn, plus a new Burmese amber taxon, †A. alethes sp.n. We demonstrate that †Burmasphecidae fam.n. clearly belongs to Apoidea and has a sister relationship with the other representatives of the superfamily. Our results indicate that †Burmasphecidae fam.n. and †Angarosphecidae are distinct lineages, with the second clearly more derived than the first. We discuss the phylogenetic relationships of these fossil lineages with extant groups of both Apoidea and other Aculeata, and present morphological evidence for the first time supporting the Formicidae + Apoidea clade. Finally, we indicate some considerations about the paleoenvironment and the nature of the Burmese amber biota, suggesting an alternative hypothesis to the island endemism described in previous works.