关键词: 西藏, 麝鼩, 分类, 形态学, 小型兽类

Abstract: Crocidura is the most speciose mammalian genus. The taxonomy of Chinese taxa remains controversial and unexplored. In this study, a total of 189 specimens of eight large-sized white-toothed shrews (mean condyloincisor length > 19.5 cm) were collected in China, including C. attenuata, C. tanakae, C. anhuiensis, C. dracula, C. lasiura, C. pullata and two undescribed species (Crocidura sp. 1 and Crocidura sp. 3) from Xizang, China. Their fur, skull and tooth morphology were compared with each other. A principal component analysis (PCA) was conducted to assess morphological variation, including cranial characters, on 14 measurements among six Crocidura species and the two undescribed species. A canonical discriminant analysis was also computed for these specimens. For further comparison, we retrieved Cyt b sequences from GenBank, which included 86 Crocidura species from China and adjacent areas. BEAST was used for Byesian Inference (BI) analyses for these Crocidura species and a general mixed Yule-coalescent model (GMYC) was used to delineate species boundaries. Two undescribed species (Crocidura sp. 1 and Crocidura sp. 3) are recognized based on morphological and molecular evidence from Zhada County of Xizang (Western China) and Motuo County of Xizang, respectively. The two new Crocidura species are described as Crocidura zhadaensis Chen, Wu et Liu, sp. nov. and Crocidura medogensis Chen, Wu et Liu, sp. nov. The diagnostic characteristics of Crocidura zhadaensis are headbody length 69 ? 77 mm, tail length 49 ? 56 mm, and condyloincisive length 20.04 ? 20.74 mm. The hair is light in color, and the whole color is brown. Three quarters of the tail is covered with sparse white long hairs, and the tail ends form short hair bundles. Cranium is flattened. There are a pair of large oval foramen on the medial side of the inferior articular surface. Maxillary U³ was significantly greater than U² in size. There is a small depression near the protocone of P⁴. The diagnostic characteristics of Crocidura medoensis are head-body length 67- 76 mm, tail length, 62-65 mm, condyloincisive length 20.33-22.21 mm. The body color is dark, the back hair is dark brown, and the belly hair is dark gray. The tail is long, often more than 85% of the head length. The cranium is full and the parietal bone is protuberant. The U¹ is the largest, two times the height of U² and U³. The lingual surface of hypocone of the M¹ is extended, and appear a half-moon shape. The mastoid process is prominent. This article includes a taxonomic key to these species, which provides basic data for further clarifying the classification and species diversity of the genus Crocidura in China.

Key words: Xizang, Crocidura, Taxonomy, Morphology, Small mammals