Reevaluation of several taxa of Chinese lagomorphs (Mammalia: Lagomorpha) described on the basis of pelage phenotype variation

Melanism is a common phenomenon in the animal kingdom. While the occurrence of melanism in lagomorphs has been less studied, this phenomenon has led to systematic confusion among different forms of pikas (Ochotona) and hares (Lepus). Within Ochotona, the Pianma black pika (O. nigritia) was established primarily based on its pelage phenotype variation compared with the sympatric Forrest's pika (O. forresti). The Gaoligong pika (O. gaoligongensis) was also described based on pelage color differences with O. forresti. However, the specific status of these two taxa has been questioned for several years. We conducted a detailed examination of the cranial characters used for the initial diagnosis of each of these forms (O. forresti, O. gaoligongensis and O. nigritia). Insignificant differences were displayed among these species, thus contradicting the classification of O. gaoligongensis and O. nigritia as separate species. Within Lepus, the Manchurian black hare (Lepus melainus) was also initially described based on the melanistic pelage possessed by this form. We conducted a detailed examination of the cranial characteristics of L. melainus and the sympatric Manchurian hare (L. mandshuricus) and confirmed the synonomy of these forms; L. melainus represents melanistic individuals of L. mandshuricus. These taxonomic mistakes probably resulted from underestimating the prevalence of melanism and the potential for adaptative variation of pelage coloration in nature. A more detailed study on the genetic background leading to the occurrence of melanistic lagomorphs is needed.