The Eurasian, chestnut-vented, Kashmir and chestnut-bellied nuthatches form another superspecies and replace each other geographically across Asia. They are currently considered to be four separate species, but the south-Asian forms were once believed to be a subspecies of the Eurasian nuthatch. A recent change in this taxonomy is a split of the chestnut-bellied nuthatch into three species, namely the Indian nuthatch, Sitta castanea, found south of the Ganges, the Burmese nuthatch, Sitta neglecta, found in southeast Asia, and the chestnut-bellied nuthatch sensu stricto, S. cinnamoventris, which occurs in the Himalayas. Mitochondrial DNA studies have demonstrated that the white-breasted northern subspecies of Eurasian nuthatch, S. (europea) arctica, is distinctive, and also a possible candidate for full species status. This split has been accepted by the British Ornithologists' Union.