Abstract:

Species of the family Spalacidae are exclusively subterranean, possessing a suite of phenotypic traits adapted to life in underground burrows, making them an important group for studying adaptive evolution. The genus Rhizomys represents a basal lineage within this family. While recent years have witnessed significant progress in molecular sequencing and adaptive evolution research on this genus, morphological comparisons and phylogenetic relationships among its constituent species and subspecies remain poorly understood due to limited availability of newly acquired specimens, and diagnostic characters still need to be clearly defined. Based on newly collected specimens and museum collections from China, we performed a systematic taxonomic study using morphological and molecular phylogenetic approaches. Our results demonstrate that Rhizomys pruinosus, R. sinensis, and R. sumatrensis can be distinguished by their long dorsal guard hairs with white tips, cheek coloration, and the ratio of tail length to head-body length (mean values: 42.3%, 27.9%, and 34.5%, respectively). The subspecies R. sinensis vestitus is significantly larger than R. s. davidi；it has a greatest skull length exceeding 70 mm, longer pinkish-brown tips on the dorsal fur, and greyish-white cheeks. In contrast, R. s. davidi has a greatest skull length less than 70 mm, greyish-brown dorsal fur with noticeably shorter brown tips. Rhizomys pruinosus senex can be distinguished from R. p. latouchei by its robust teeth and sparser dorsal long guard hairs with a shorter white tip section. Phylogenetic reconstruction based on the cytochrome b gene revealed a closer relationship between R. pruinosus and R. sumatrensis, with R. sinensis representing an early-diverging lineage within the genus. Interspecific genetic distances ranged from 9.3% to 15.9%. At the intraspecific level, the genetic distance was 2.3% between the subspecies R. s. vestitus and R. s. davidi, and 0.4% between R. p. senex and R. p. latouchei, indicating varying degrees of differentiation among subspecies. This study provides foundational data for the systematics of the genus Rhizomys; However, a definitive taxonomic assessment of R. wardi still awaits more comprehensive sampling.

Key words: Rhizomyinae, Morphology, Phylogeny, Cyt b, Subspecies, Taxonomic key

摘要：

鼹形鼠科（Spalacidae）物种专营地下生活，具有适应地下洞穴环境的系列表型特征，是适应进化研究的重要类群。竹鼠属（Rhizomys）位于该科系统演化的基部分支，近年来分子测序及适应进化研究逐步深入，但受新增标本量限制，属内物种及亚种形态度量比较和系统发育关系研究仍较薄弱、鉴别特征还需厘定。基于国内新采集竹鼠标本和查看的馆藏标本数据，利用形态学和分子系统学方法开展分类研究，结果表明：银星竹鼠（R. pruinosus）、中华竹鼠（R. sinensis）和大竹鼠（R. sumatrensis）可依据体背尖端白色的长柱状毛、脸颊颜色及尾长比例鉴定区分，尾长与头体长之比的均值分别为42.3%、27.9%和34.5%；中华竹鼠四川亚种（R. s. vestitus）个体显著大于福建亚种（R. s. davidi），前者颅全长大于70 mm，体背毛尖粉棕色段较长，脸颊灰白色，后者颅全长小于70 mm，体背灰棕色、毛尖棕色段较短；银星竹鼠云南亚种（R. p. senex）可依据牙齿较粗壮、体背柱状长毛明显稀疏且尖端白色区段较短的特征与华南亚种（R. p. latouchei）相区分；基于Cyt b基因构建的系统发育树显示银星竹鼠与大竹鼠亲缘关系较近，中华竹鼠为竹鼠属内较早分化的类群，种间遗传距离为9.3% ~ 15.9%，中华竹鼠四川亚种与福建亚种、银星竹鼠云南亚种与华南亚种间的遗传距离分别为2.3%和0.4%，揭示不同亚种间的分化程度存在差异。本研究为完善竹鼠属系统分类积累了基础数据，关于暗褐竹鼠（R. wardi）的分类地位有待更全面的采样研究来确定。

关键词: 竹鼠亚科, 形态学, 系统发育, 细胞色素b基因, 亚种, 分类检索表