Systematics of the Australian members of bee fly subfamily Bombyliinae and molecular phylogeny of the superfamily Asiloidea using anchored hybrid enrichment and transcriptome data

Abstract

The Bombyliidae (bee flies), comprising 15 subfamilies, and more than 250 genera and 5,000 described species, and is one of the most species-rich families of lower Brachycera (Diptera) (Evenhuis and Greathead, 2015; Yeates, 1994). The family gets its common name from its resemblance to bees, as the adult bee flies feed on nectar and pollen and are important pollinators (Armstrong 1979; Heard et al., 1990). The phylogenetic position of Bombyliidae has never been strongly supported. The most widely used contemporary classification schemes nowadays placed Bombyliidae in the superfamily Asiloidea, as sister to all the remaining Asiloidea (Woodley, 1989; Weigmann et al., 2011). However, the relationship of Bombyliidae as sister to the remaining Asiloidea + Eremoneura has also been supported by recent studies (Trautwein et al., 2010; Shin et al., 2017). The relationships between bee fly subfamilies have never been resolved robustly. Higher level phylogenetic studies over the past few decades have been based on quantitative analysis of morphological (Yeates, 1994) and molecular data (Trautwein et al., 2011), however, not many subfamily relationships were strongly supported. In this thesis, two phylogenomic analysis were performed focusing on the phylogenetic position of Bombyliidae and the family relationships of Asiloidea, and an analysis with more focused taxon sampling for the subfamily relationships of Bombyliidae, respectively. For the Asiloidea phylogenomic analysis, I generated combined matrices from both the transcriptomes of 36 species and anchored hybrid enrichment (AHE) data from 89 species, representing 101 Asiloidea (including Bombyliidae) species, and 24 outgroup species. Based on the phylogenomic results, the monophyly of Bombyliidae was supported with Heterotropinae and Mythicomyiinae as successive sister-groups to the remainder of the family. Results confirmed that the Asiloidea is not monophyletic, with Bombyliidae sister to the remaining Asiloidea + Eremoneura. For the phylogenomic analysis of Bombyliidae subfamilies, 18 transcriptomes and AHE data for a further 95 terminals were used, including 94 bee fly species and 12 representative outgroup families. Ten out of 15 subfamilies were recovered as monophyletic. The relationships within Bombyliidae were largely resolved, with low support at a small number of nodes. Regarding their morphology, the sand chamber appeared to evolve once, but was lost multiple times. The cup-shaped postcranium is more labile, evolving at least four times independently and being lost twice. Therefore both "sand chamber subfamilies" and "Tomophthalmae" are not monophyletic in the phylogenomic trees. The Bombyliinae is one of the largest subfamilies of bee flies distributed worldwide, comprising over 1,100 species described in 73 known genera. I present the first phylogenetic hypothesis for this subfamily, based on 157 adult morphological characters scored for 123 species representing 60 genera. Five previously recognized tribes are revised and four new tribes are erected. I placed almost all genera in the tribal classification, based on the phylogenetic results and available character evidence. A Gondwanan origin for the major lineages of Bombyliinae is strongly indicated by my biogeographic analysis which reconstructs ancestral areas. The Australian Bombyliini currently has 13 described genera and 68 described species (Evenhuis & Greathead, 1999). I established the phylogeny of the Australian members of the subfamily Bombyliinae using morphological characters. Phylogenetic analysis recovered the relationships between the recognised Australian genera of Bombyliinae and clarified generic limits. Moreover, several genera have been revised. Based on the phylogenetic results, six new genera and 32 new species are described; three generic and two specific junior synonyms are identified; 11 new combinations are proposed. Taxonomic keys are also updated for the use of future workers.