A taxonomic re-assessment of the widespread oriental bumblebee Bombus flavescens (Hymenoptera, Apidae)

Bombus flavescens Smith is one of the most widespread bumblebee species in the Oriental region. Due to colour polymorphisms, this species or species-complex has been a challenge for taxonomy. This study aims to assess the taxonomic status of the flavescens-complex using evidence from COI barcodes and morphology. We then reconstruct its biogeographic history from a phylogenetic analysis of populations across the current range, combining COI with 16S and nuclear PEPCK data. Despite a large range of polymorphisms across its distribution, the results show that B. flavescens is a single species based on algorithmic species delimitation methods, and it is clearly separated from its sister species, B. rotundiceps Friese. We suggest that B. flavescens diverged from its sister lineage in the Himalaya and dispersed into Southeast Asia in the Pleistocene. Conservation of the widespread B. flavescens will need to consider its several unique island populations.