Genetically solving a zoological mystery: Was the kouprey (Bos sauveli) a feral hybrid?

A famous zoological discovery of the 20th century was that of the kouprey Bos sauveli, a medium-sized ox inhabiting Cambodian forests. The kouprey was suspiciously intermediate between banteng oxen and domestic zebu cattle in its structure. Mitochondrial DNA sequences of mainland banteng are compared here with a published kouprey sequence, and the comparison demonstrates a close relationship. Either the kouprey derives partly from banteng or (less likely) these particular banteng acquired kouprey DNA via recent genetic introgression. The kouprey may have been a feral hybrid form, a descendant of domestic oxen, rather than a natural species.