Search

We describe a new species of squirrel (Sciuridae, Callosciurus) from Hon Khoai Island, located off the coast of southern Vietnam (centered at ca. 8°26′08″N, 104°49′58″E) and discuss its phylogenetic position in the genus Callosciurus. Compared to other Callosciurus occurring on the Indochina Peninsula, the new species (Callosciurus honkhoaiensis) is strikingly small, especially head and body length, body mass, and hind foot length. Unlike other species of Callosciurus, the hairs at the tip of the tail are white with a black base, and the venter and feet are whitish cream. The new species at present is known only from the type locality, Hon Khoai Island. Phylogenetically, the new species is closely related to C. caniceps, suggesting that it evolved from C. caniceps or an ancestor in common with C. caniceps, possibly during the Pliocene. Genetic distances between the 2 species calculated from comparison of mitochondrial cytochrome b sequences are 10.1–10.3%. During both glaciations and interglaciations of the Pleistocene, the new species may have been isolated from other Callosciurus populations by rivers and sea, respectively. [ABSTRACT FROM AUTHOR]

The taxonomic position of Annandale's rat, Rattus annandalei (Bonhote, 1903), has been uncertain given its mix of Rattus-like and Sundamys-like morphological features. Annandale's rat and all described species in Sundamys (the lowland S. muelleri and the montane S. maxi and S. infraluteus) are endemic to Sundaland, a center of diversification and endemism for their tribe, the Rattini. Using mitochondrial genomes and 3 nuclear markers (rag1, rbp3, ghr), we provide the 1st phylogenetic framework for Sundamys. We find that R. annandalei is nested within Sundamys and that the 4 species likely diverged during the Pleistocene. We move R. annandalei to Sundamys and provide an emended diagnosis for Sundamys. Using geometric morphometric analyses of skulls and mandibles, we identify morphological differences between lowland and highland species of Sundamys that may be associated with adaptations to distinct diets. [ABSTRACT FROM AUTHOR]

Knowledge of the diversity and relationships of species in many groups of plants and animals in Southeast Asia is severely limited, preventing an integrative understanding of evolutionary and ecological processes in island archipelagos. We generated a 3-locus DNA sequence data set to estimate phylogenetic relationships among species and populations of Maxomys, a genus of rodents endemic to Southeast Asia. Our inclusion of Crunomys as a potential outgroup supported the monophyly of Crunomys, but the genus was deeply nested within Maxomys. Because of the relatively ancient divergences (mean uncorrected p-distances up to 0.15 in cytochrome-b sequences) among species of Maxomys and short branch lengths among basal lineages of the phylogeny, we obtained little support for the oldest relationships in Maxomys + Crunomys. However, our analyses revealed unrecognized diversity in the form of divergent populations both between and within islands and the presence of 2 potentially undescribed species from Sulawesi. The Maxomys and Crunomys of Sulawesi belonged to 4 clades sister to extralimital species, suggesting that repeated overwater dispersal between Sundaland--Philippines and Sulawesi was an important isolating mechanism in the history of this group. [ABSTRACT FROM AUTHOR]