Reflecting the state of invertebrate taxonomy globally, many bee taxa in Australia are in need of revision, and this includes the most species-rich endemic subfamily, the Euryglossinae. In addition to undescribed species, many euryglossine species have been described from only a single sex. Over 30 taxonomic papers on euryglossines have been published, however the majority of these were by a single author, and before the advent of molecular technologies that can be used to efficiently and reliably associate the sexes of these often sexually-dimorphic species.

Additionally, the reproductive behaviours of most bee species are unknown, and published observations of reproductive activities are few and far between. Based on DNA barcoding we associate the male of Xanthesma (Xenohesma) perpulchra (Cockerell, 1916) (Hymenoptera: Colletidae), with the female of Xanthesma (Xanthesma) brachycera (Cockerell, 1914). We propose that Xanthesma perpulchra syn. nov. is a junior synonym of X. brachycera, and, due to the enlarged male eyes, that X. brachycera should be placed in subgenus Xenohesma. Consistent with other X. (Xenohesma), we report swarming behaviour for this species observed in bushland remnants within an urbanised biodiversity hotspot, which can be related to the male’s enlarged eyes. Our research has indicated the value of DNA barcoding, and raises further questions regarding the taxonomy of this diverse endemic Australian subfamily.