The Liberian Greenbul Phyllastrephus leucolepis is known only from the Cavalla Forest, Liberia, where it was seen between 1981 and 1984 but has not been found since the collection of the type, and only, specimen. It is similar to the common and widespread Icterine Greenbul P. icterinus, from which it differs primarily in having white subterminal spots on the wing coverts and all flight feathers. Its validity as a distinct species has been questioned but left unresolved. This paper describes the first genetic study of the Liberian Greenbul, to attempt to determine whether it is a distinct species, a plumage variant of Icterine Greenbul, or a hybrid. Total genomic DNA was isolated independently by two separate laboratories from the type specimen, as well as from Icterine and White-throated Greenbuls P. albigularis sampled close to the type locality in Liberia. Mitochondrial and nuclear DNA was sequenced and compared to that of Icterine and other greenbul species from Liberia and elsewhere. Sequence analysis of three mitochondrial genes and one nuclear gene showed that the Liberian Greenbul is not a hybrid but falls within the range of intraspecific genetic variation observed in the Icterine Greenbul. Reasons for this are discussed, but the most likely explanation is that the Liberian Greenbul represents a plumage variant of the Icterine Greenbul. The alternative possibilities that the Liberian Greenbul represents a distinct species which only recently diverged or has ongoing gene flow with the Icterine Greenbul cannot be formally refuted. Conservation implications for the Cavalla Forest are discussed.
Bibliographical noteWe thank Jochen Martens for his long-lasting patience in dealing with the specimen of leucolepis, and Brian Hillcoat for comments and advice. It is hardly possible to thank by name all those who have supported WG over the past 30 years and more since 1981 in the fields of forest ecology and ornithology in eastern Liberia. In particular, we express gratitude to Alex Peal and Theo Freeman, both Heads of Wildlife and National Parks, for their many years of cooperation, and the Silviculture Officers Wynn Bryant, Momo Kromah and Steve Miapeh. The knowledge of the tree experts Joe Keper and Daniel Dorbor helped us to gain insights into the ecological complexities of the relationship between man, birds and trees. William Toe worked for three years as bird trapper and assistant in bird banding. WG’s attachment to the University of Liberia and to the students who so often accompanied him was made possible by Ben Karmorh from the Environmental Protection Agency (EPA) and University of Liberia. NABU, the German Conservation Society, has supported the Liberian projects for almost 30 years now. We also thank Nigel Collar, Françoise Dowsett-Lemaire and Hannah Rowland for comments and advice. We thank the African Bird Club and the Royal Society for the Protection of Birds for helping to fund the 2013 expedition to the Cavalla Forest, in particular Alice Ward-Francis, Robert Sheldon, Alan Williams and Keith Betton. We also are extremely grateful to Michael Garbo and staff of the Society for the Conservation of Nature in Liberia for all manner of help with the expedition, to Harrison Karnwea and colleagues at the Forest Development Authority of Liberia for permissions and other support, as well as to Emmanuel Loqueh, Trokon Grimes, Flomo Molubah and Amos ‘Dweh’ Dorbor for being such excellent companions in the field. YL performed the genetic work as part of her M.Sc. (Genetics) at the University of Aberdeen, whose support is acknowledged.
- Liberian Greenbul
- Icterine Greenbul