Systematics and phylogeny of Cheloninae (Hymenoptera: Braconidae) with an emphasis on Australian species.

Abstract

This study explores the systematics of the genera of Cheloninae (Hymenoptera: Braconidae) and presents a number of taxonomic revisions of Australian species. The phylogenetic relationships of the world genera were analysed by applying molecular phylogenetic analyses (based on three markers: CO1, 28S and ef1α, totalling 1454 bp of sequenced data) combined with morphological data. The results show that most genera are monophyletic, although the current tribes were not. Also the previously recognised subgenera of Chelonus were not recovered as monophyletic and thus do not represent valid subgenera. A total-evidence approach of 84 sequenced species and 16 dated fossil taxa to calibrate the molecular clock was performed to estimate the age of the subfamily and component genera. Divergence dating analyses and ancestral range reconstruction suggest that the Cheloninae evolved in the Neotropics 150 Ma ago. Prior to this study, 45 chelonine species were recognised from Australia, of which the majority were described more than 80 years ago. Yet there are many undescribed species, some of which could not be easily assigned to existing genera. Thus the first step of a taxonomic revision was to assess the current state of the fauna. This study evaluates the species richness of the Australian chelonines, provides a key to genera to facilitate their identification, provides a checklist of species and notes on their taxonomy, and discusses their biology. In so doing two new genera, Austroascogaster gen. nov. and Phanaustrotoma gen. nov. were recognised from Australia, together comprising six new species. Additionally, the genus of Wushenia, which was previously known only from a single species from Taiwan has been found in Australia and is represented by a new species. A revision of the Australian Phanerotomella species has been conducted, revealing 18 new species. They are described and the three previously species of Phanerotomella redescribed. Additionally, nine species belonging to the genera Phanerotoma and Ascogaster were discovered from central arid Australia, and two species of Phanerotoma from this area are redescribed. Dichotomous keys are included to facilitate identification of the species. Finally, the broader implications of the study and future research directions are discussed.