Taxonomic revision of the Carebara oni species group, with descriptions of two new species from Vietnam (Hymenoptera, Formicidae, Myrmicinae)

The myrmicine genus Carebara is comprised of subterranean ants mainly distributed in tropical and subtropical regions. Based on morphological characters found in the major and minor worker subcastes, we established that the Carebara oni species group is comprised of three species: C. eguchii sp. nov., C. bifida sp. nov., and C. oni (Terayama). The two new species were collected from Mt.

Phansipan and Cuc Phuong National Park, respectively, in northern Vietnam. Members of this species group are distinguished from other congeners by the massive mesosoma in major workers, the pronounced median clypeal projections in minor workers, and the nine-segmented antennae and six-toothed mandibles in both worker subcastes. Herein, we describe the new species, provide diagnostic characters for the species group, and present a worker-based identification key to species.