Sitta (frontalis) oenochlamys (Sharpe, 1877)
The Palawan taxon, palawana Hartert, 1905, is very similar to Bornean corallipes (Sharpe, 1888), and has the bright red bill that places it with S. frontalis. Curiously, all the other populations in the Philippines have yellow bills. Although the main dispersal route of birds from Asia into the Philippines has come through Borneo (Dickinson et al., 1991) some species seem to have arrived from China either through Taiwan or perhaps earlier and more directly. It is not impossible that the root stock of solangiae and these forms is the same. Yet it is equally possible that they arrived through Palawan at a time before the present red-billed population had reached there. To determine this and to settle whether oenochlamys should be treated as an endemic Philippine species or a species that includes solangiae from Vietnam and Hainan a molecular study is essential. It also remains possible that it is neither but is closer to S. frontalis.