Phylogenetic Relationships Among Treeshrews (Scandentia): A Review and Critique of the Morphological Evidence

Although the supraordinal relationships of Scandentia (treeshrews) have been studied in great detail from both morphological and molecular perspectives, the phylogenetic relationships among treeshrews have been largely ignored. Here we review several published studies of qualitative morphological variation among living treeshrews and their contribution to our understanding of intraordinal phylogenetic relationships. Reanalysis of the data from each of these studies demonstrates that none of the trees in the original publications represents the most parsimonious interpretation. In addition to performing new analyses, we argue that all such studies to date suffer from one or more fundamental shortcomings, notably the failure to include reference to nonscandentian outgroups and the a priori assumption of generic monophyly of the relatively speciose genus Tupaia. Parsimony analyses of these data sets fail to resolve either intergeneric or interspecific relationships. Finally, several inconsistencies and conflicts with respect to character coding both within and between published studies are discussed. We conclude that a more rigorous investigation of morphological character state variation is sorely needed, one that explicitly identifies voucher specimens and does not make any assumptions of generic monophyly. This is necessary not only for the purpose of resolving phylogenetic relationships, but also for inference of ancestral states in a group that continues to figure prominently in studies of placental mammal diversification.     

Lesula: A New Species of Cercopithecus Monkey Endemic to the Democratic Republic of Congo and Implications for Conservation of Congo��s Central Basin

In June 2007, a previously undescribed monkey known locally as “lesula” was found in the forests of the middle Lomami Basin in central Democratic Republic of Congo (DRC). We describe this new species as Cercopithecus lomamiensis sp. nov., and provide data on its distribution, morphology, genetics, ecology and behavior. C. lomamiensis is restricted to the lowland rain forests of central DRC between the middle Lomami and the upper Tshuapa Rivers. Morphological and molecular data confirm that C. lomamiensis is distinct from its nearest congener, C. hamlyni, from which it is separated geographically by both the Congo (Lualaba) and the Lomami Rivers. C. lomamiensis, like C. hamlyni, is semi-terrestrial with a diet containing terrestrial herbaceous vegetation. The discovery of C. lomamiensis highlights the biogeographic significance and importance for conservation of central Congo’s interfluvial TL2 region, defined from the upper Tshuapa River through the Lomami Basin to the Congo (Lualaba) River. The TL2 region has been found to contain a high diversity of anthropoid primates including three forms, in addition to C. lomamiensis, that are endemic to the area. We recommend the common name, lesula, for this new species, as it is the vernacular name used over most of its known range.     

Skeletal Variation and Taxonomic Boundaries in the Pen-tailed Treeshrew (Scandentia: Ptilocercidae; Ptilocercus lowii Gray, 1848)

The Pen-tailed Treeshrew, Ptilocercus lowii Gray, 1848, is a small arboreal mammal from Southeast Asia. It is the only extant species of Ptilocercidae and includes two subspecies: P. l. lowii from Borneo and offshore islands, and P. l. continentis from the Malay Peninsula, Sumatra, and smaller islands, including the Batu and Mentawai Islands. Intraspecific taxonomic boundaries in Ptilocercus have yet to be rigorously evaluated using modern morphological methods, so we investigated the morphometric variation between these subspecies using quantitative cranial and postcranial data obtained from museum specimens. Multivariate analyses revealed limited overlap between P. l. lowii and P. l. continentis in cranioskeletal morphospace, indicating some divergence of these two lineages. Future studies should incorporate additional morphological and molecular data to further test whether these lineages represent two distinct species. Recognition of two Ptilocercus species would have conservation implications for both populations, which should be reevaluated across their separate ranges in light of region-specific threats. Additional biological surveys, particularly from undersampled island populations, will be critical in reassessing the distribution and conservation priorities for P. lowii.