Colymbus ruficollis Vroeg, Cat. d'Ois., Adum., p. 6 (1764).
The typical form found in Europe has more black on the chin; the white on the base of the primaries and the secondaries is less in extent.
The Indian form, albipennis, is now generally considered indistinguishable from the African form capensis. Some specimens from Africa certainly have the upper parts very black but a few Indian specimens closely approach them in depth of colour and there is so much overlapping that it seems advisable to retain them for the present under the one name. Comparison of series of breeding birds may show that division is necessary.
The Philippine form, which might possibly wander into Southern Tenasserim, has chestnut under the eye instead of black and is darker above with a longer bill.