| Publication Type: | Journal Article |
| Year of Publication: | 1983 |
| Authors: | FRITH, CB, FRITH, DW |
| Journal: | Zoological Journal of the Linnean Society |
| Volume: | 78 |
| Issue: | 1 |
| Date Published: | 1983 |
| ISBN Number: | 1096-3642 |
| Keywords: | Aceros coronatus, Anthracoceros, Anthracoceros coronatus, Bucerotidae, hybrid zones, immature plumage, sexual dimorphism, synonomies, World |
| Abstract: | An examination of 758 Anthracoceros skins in eight major collections, leads us to recognize six taxa in five species within the genus: Anthracoceros coronatus, A. albirostris albimstris, A. a. convexus, A. malayanus, A. marchei and A. montani. The subspecies A. malayanus deminutus Sanft is considered invalid as are earlier erected subspecies of A. albirostris on the South-East Asian mainland and Indonesian islands. The previous arrangement, of species in which A. coronatus was conspecific with A. albirostris, resulted from a misinterpretation of relative sexual dimorphism in these species. Anthracoceros coronatus exhibits very limited sexual dimorphism in bill and casque shape and coloration whereas it is marked, and similar, in both A. a. albirorostris and A. a. convexus which differ much from A. coronatus in both sexes. This is contrary to data presented, erroneously, in the standard hornbill taxonomy (Sanft, 1960). Supposed hybrid zones between the species A. coronatus and A. albirostris, and between the two subspecies of A. albirostris, are discounted as being based on sightings on immature and/or abnormally pigmented individuals in the areas concerned. Size variation within A. albirostris is examined, indicating a north to south decrease in size within A. a. albirostris in compliance with Bergmann's Rule; and a random variation in size across the island distribution of A. a. convexus. Extensive, but not exhaustive, synonomies are presented to clarify earlier problems created by the synonomy. Full plumage and soft part descriptions and measurements of wing, tail, tarsus, bill and casque are presented in support of our conclusions. Vernacular names, too, have caused confusion and we suggest names that will clarify the situation with the hornbills of the world in mind. Our data do not support the view that there is a unique immature plumage in A. coronatus and A. albirostris, involving black pigment on outer tail feathers. There is evidence, however, of a gradual loss of such pigmented feathers through life, the outer feathers being replaced before those closest to the central pair. We also note a clinal correlation in increasing occurrence of the black pigment on normally white tail feather tips in A. a. albirostris from north to south. |
| URL: | http://dx.doi.org/10.1111/j.1096-3642.1983.tb00862.x |
| Short Title: | Zoological Journal of the Linnean Society |
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