Morphometric analysis within populations of Hylomyscus walterverheyeni (Rodentia: Muridae) confirms complex relationships between small rodent populations of West Central African forests

Abstract

Our recent morphometric study on the strictly forest-dwelling small rodent (Praomys misonnei) in West Central Africa revealed complex relationships between populations. The present study tests this hypothesis on another species of forest rodent (Hylomyscus walterverheyeni), and more precisely compares specimens from Kessala (Gabon) with specimens from southern Cameroon. Sixty-eight specimens were used for the morphometric analyses, and four standard external characters were measured: head + body length, tail length, hindfoot length, and ear length. Highly significant morphometric differences were observed between the H. walterverheyeni populations at the local and regional scales. A principal component analysis showed that the Gabonese H. walterverheyeni populations were morphometrically closer to one another than to the Cameroonian ones. Moreover, the body size of the Gabonese H. walterverheyeni populations was smaller than that of the Cameroonian populations. Overall, H. walterverheyeni is characterized by a local morphometric structure pattern similar to that of P. misonnei. These new results further support the scenario of complex relationships between the forest populations of West Central African rodents. This suggests the existence of persistent local biogeographical barriers despite several forest expansion episodes in the upper Pleistocene, as documented by the landscape history of West Central Africa.