A new subspecies of the Red-billed Hornbill, Tockus erythrorhynchus, from West Africa

The Red-billed Hornbill, Tockus erythrorhynchus (Temminck), over most of it s distribution range, has pale yellow or pink facial skin. However, in Sene gal, The Gambia and Western Mall, where all Red-billed Hornbills are usuall y referred to the nominate subspecies, oil adults have black circumorbital (facial) bare skin, conspicuous bn live birds as well as on skinned specime ns, and brown eyes. Field and museum studies suggest that these block-faced and brown-eyed birds from the western-most part of Africa belong to a yet undescribed subspecies. A review of the documents (including various black- and-white and colour plates) on which Temminck based his original descripti on and naming of the species shows that there is uncertainty about the loca lity of the type specimen illustrated in the original description. Furtherm ore, neither the plates nor their accompanying texts show the black facial pattern characteristic these western-most West African populations. To avoi d confusion In future, and to ensure nomenclatural stability, a new type-lo cality and a neotype ore designated for nominate Tockus erythrorhynchus, an d a new name is proposed for the populations extending from Senegal, The Ga mbia and Guinea to the inner Niger Delta in Moll. Further studies are neede d to ascertain the status of these brown-eyed and block-faced birds: their facial colouration pattern could be associated with other eco-ethological c haracters and could ploy an important role in specific mote recognition sys tems. IA French translation of the abstract is provided on p. 366.].