Systematics and host associations of the Australian Gasteruption (Gasteruptiidae: Evanioidea)

Author: Ben Parslow

  • Thesis download: available for open access on 9 Nov 2023.

Parslow, Ben, 2020 Systematics and host associations of the Australian Gasteruption (Gasteruptiidae: Evanioidea), Flinders University, College of Science and Engineering

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The wasp genus Gasteruption (Gasteruptiidae: Gasteruptiinae) is found in all biogeographical regions with approximately 514 described species worldwide. Their larvae are considered predator-inquilines in the nest of aculeate Hymenoptera, but these records are often conflicting isolated observations. The Australian fauna is considered the most diverse with 114 described species, however, little taxonomic work exists for the genus since the last formal revision in 1957. Additionally, there has been a paucity of molecular research on the genus with no exploration into evolutionary relationships. In this thesis of work, I summarise all available information on the biology and host association of the Gasteruption, providing insights into the specialisation and patterns of host utilisation across the world-wide distribution of the genus. Correct identification of both parasite and host are extremely important to further explore relationships; this was evident when reviewing the literature as the majority of Australian records are without species identification due to the current state of the taxonomy. A revision of the Australian fauna was conducted to allow further identification of Australian species. Here I redescribe 90 species, including descriptions for three new species and provide an identification key to treated species. Unfortunately, there are many missing type specimens and some species are only known from males, making identification difficult. To provide additional identification tools I assembled a DNA barcode dataset of 187 sequences from a combination of publicly available sequences and newly sequenced material for the Gasteruptiidae. I tested six molecular species delimitation methods and found tree-based methods effective at delineating species. However, there is still a large unknown Australian diversity, with many species represented by only a single specimen. These single-gene trees effectively informed species boundaries among closely related species but have limited reliability for deeper phylogenetic relationships. To explore the evolutionary relationships within the family, I used three gene fragments with an emphasis on the Gasteruption. These results suggest the crown age for Gasteruption is younger than previously suggested with support indicating the group initially radiated from the Australasian region and coincides with the radiation of their known bee hosts. There are limitations with the produced multilocus phylogeny with low support recovered within the main Gasteruption clade. To improve resolution, I used target capture of ultraconserved elements and increased taxon sampling across biogeographic regions and within the Gasteruptiinae. These data produced a better-resolved phylogeny with increased support at basal nodes, providing a robust framework for future exploration of evolutionary relationships within the Gasteruption. This research provides the first major contribution to the Australian Gasteruption in over 60 years, with a complete review of biology, treatment of species and the exploration of evolutionary relationships.

Keywords: Taxonomy, Hymenoptera, phylogenetics

Subject: Biodiversity and Conservation thesis

Thesis type: Doctor of Philosophy
Completed: 2020
School: College of Science and Engineering
Supervisor: Michael Schwarz