Niviventer andersoni (Thomas, 1911) is an endemic species of China. This taxon has the largest body-size when compared with congeneric species of the genus Niviventer Marshall, 1976. Fossil records showed this species extended to the low altitude regions of Southeast China during the late Quaternary in Chongqing and Guizhou, suggesting its potentiality of southward expansion during the cold climate. However, historical resources suggested that N. andersoni is mainly confined to the Southwestern mountainous region in China. A comprehensive study on its morphological differentiation is also lacking. Our study is intended to explore the intraspecific morphological variation among different populations and revise the distribution range of this species by integrating information from collection records, DNA sequences, and morphological data. Our databases were derived from specimens preserved in major zoological museums of the world, field work carried out in the last ten years, and fossil records compiled from all available historical publications. Phylogenetic structure analyses based on Cytochrome b displayed three genetic lineages within this species. N. andersoni andersoni is included in the lineage of Mountains around Sichuan Basin and Southeast and Central China, N. a. ailaoshanensis is included in the lineage of Southwest Yunnan and Southeast Tibet. Based on statistical

analyses of craniodental measurements, significant morphological variation was presented beween different geographical populations of N. andersoni. Molecular voucher specimens and museum collections showed that N. andersoni is widely distributed in Central and Southern China, including southeastern Tibet region to the Hengduan Mountains, Qinling Mountains, and the southeast Wuling Mountains. However, when compared with the elevation of fossil sites, the distribution of extant populations showed clear trend of upward shift.

安氏白腹鼠（Niviventer andersoni） (Thomas, 1911) 是中国特有种，也是白腹鼠属体型最大的种类。这一物种的基础研究较为薄弱，形态分化也缺乏系统分析。化石记录显示这一物种在第四纪晚期曾广泛分布于中国川黔地区中低海拔环境，然而国内外主要的数据库和专著均显示安氏白腹鼠现生种群分布区较为狭窄，主要在中国西南地区。本文通过检视国内外主要动物博物馆馆藏标本，结合课题组近十年来的野外采集，对安氏白腹鼠不同地理种群的形态分化进行研究，综合利用采集记录和博物馆馆藏数据对这一物种的分布范围进行修订。基于线粒体细胞色素b（Cyt b）的系统发育分析显示这一物种具有3个遗传支系。安氏白腹鼠指名亚种包含于四川盆地周边山脉与华中、华南支系，安氏白腹鼠哀牢山亚种分布于云南西南及藏东南支系。基于头骨测量数据的分析显示安氏白腹鼠不同地理种群已产生显著的分化。安氏白腹鼠现生种群从中国西藏东南地区到秦岭，甚至武陵山地区中高海拔森林环境均有分布，但与第四纪晚期这一物种的化石分布记录相比，现生种群分布海拔已明显上升。