Phylogenetic Position ofCallosciurus erythraeus griseimanusfrom Vietnam in the GenusCallosciurus

Abstract

Callosciurus squirrels are widely distributed in Southeast Asia, eastern parts of South Asia, and southern parts of East Asia (Wilson and Reeder 2005). In this genus, there are 15 species; each species has many geographical forms (Corbet and Hill 1992; Wilson and Reeder 2005). Especially, at present, the Pallas’s squirrel (Callosciurus erythraeus) has 25 subspecies (atrodorsalis, bartoni, bhutanensis, bonhotei, castaneoventris, erythrogaster, flavimanus, gloveri, gordoni, griseimanus, harringtonii, hendeei, hyperythrus, intermedius, michianus, ningpoensis, pranis, rubeculus, shanicus, siamensis, sladeni, styani, thai, thaiwanensis, and zimmeensis) (Wilson and Reeder 2005). These many geographical forms clearly make sub-specific classification of C. erythraeus complicated (e.g., Lekagul and McNeely 1988). Of these subspecies, 18 (atrodorsalis, bonhotei, castaneoventris, flavimanus, gloveri, gordoni, griseimanus, hendeei, michianus, ningpoensis, pranis, rubeculus, shanicus, siamensis, styani, thai, thaiwanensis, and zimmeensis) were previously assigned to a distinct species, the bellybanded squirrel C. flavimanus (Ellerman and MorrisonScott 1951; Moore and Tate 1965). Corbet and Hill (1992), however, regarded C. flavimanus as a subspecies of C. erythraeus (i.e., C. erythraeus flavimanus) and assigned all C. flavimanus subspecies to C. erythraeus. At present, this taxonomic status is generally accepted (Wilson and Reeder 2005). Debates on subspecific classification of C. erythraeus have been based on morphological characteristics, such as skull shapes and pelage patterns, but not on any other systematic characteristics, such as molecular and cytogenetic data. To provide additional evidence for resolving the taxonomic and systematic status of C. erythraeus subspecies, we examined the phylogenetic position of C. erythraeus griseimanus among Callosciurus squirrel species by using mitochondrial (mt) cytochrome b gene sequences. Callosciurus erythraeus griseimanus is found in only the southeastern parts of the Indochina Peninsula. Judging from its restricted distribution pattern, this subspecies may be genetically distinct from other C. erythraeus subspecies and other Callosciurus species. We discuss here where we place this squirrel in the phylogeny of Callosciurus.