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| Eospalax muliensis Zhang, Chen & Shi, in Zhang, Lei, Zhou, Chen & Shi, 2022. |
Abstract
Zokors in the genus Eospalax, which are endemic to northern and western China, are subterranean rodents that inhabit various niches, including grasslands, high-altitude meadows, forests, and farmlands. Six species in Eospalax were described a century ago but their taxonomy and phylogeny remain controversial. In this study, we performed high-depth whole-genome sequencing of 47 zokor samples, comprising all six previously described species. Genomic analyses revealed a reliable and robust phylogeny of Eospalax and supported the validity of the six named species. According to the inferred phylogenetic relationships, Eospalax first divergent into two clades in the early Pliocene (ca. 4.68 million years ago (Ma)), one inhabiting the high-altitude Qinghai-Tibet Plateau and adjacent regions, and the another inhabiting the low-altitude Loess Plateau and Qinling-Daba Mountains. The most recent divergences occurred between E. baileyi and E. smithii and between E. rufescens and E. rothschildi in the late Pliocene (ca. 2.09 and 2.19 Ma, respectively). We also collected specimens of zokors in the southern Hengduan Mountains (Muli County, Sichuan Province), far from the known distributions of all other zokors. Morphological and molecular analyses strongly suggested that the specimens represent a new species, formally described here as Eospalax muliensis sp. nov. The new species belongs to the high-altitude clade and diverged from closely related species (ca. 4.22 Ma) shortly after the first divergence in Eospalax. Interestingly, Eospalax muliensis sp. nov . possesses more supposedly plesiomorphic characters, suggesting a possible origin of the genus in the Hengduan Mountains.
Keywords: Zokor, Eospalax, Phylogenomic analyses, New species, Hengduan Mountains
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| Image of typical Eospalax muliensis sp. nov. (upper panel) and aboveground mound (lower panel). |
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| Geographic distribution of sampling sites. |
Eospalax muliensis Zhang, Chen & Shi, sp. nov.
Suggested common name: Muli zokor;
木里鼢鼠 (Muli Fenshu)
Diagnosis: Eospalax muliensis sp. nov. can be distinguished from other described species of Eospalax by a combination of the following characters: size small (mean BW=155.64 g; mean GLS=40.52 mm); tail relatively long, densely hairy; nose-pad trifoliate; rostrum weak, nearly rectangular, nasals small, posterior border of nasals transverse, anterior halves of premaxilla nearly aligned with nasals; braincase well-domed, temporal ridges not conspicuous, parallel in front, lambdoid crests only present on side of skull; occipital shield with developed occipital ridges, extending well posteriorly, almost forming plane with occipital condyle; about 1/3 of incisive foramina included within maxillae, remaining 2/3 of incisive foramina included within premaxillae; palate and pterygopalatine fossa large, M2–M2 almost equal to LUM; M3 with two reentrant angles on outer side.
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| Dorsal, ventral, and lateral views of skull and mandible of Eospalax muliensis sp. nov. (KIZ 040324, holotype) (A), E. baileyi (DF 004) (B), E. cansus (LM 001) (C), E. fontanierii (FS 001) (D), E. rothschildi (ZB 001) (E), E. rufescens (FP 001) (F), and E. smithii (XZ 001) (G) |
Etymology: The species name muliensis is derived from Muli County, the type locality of the new species in Sichuan Province, China, and the Latin adjectival suffix -ensis means “belonging to”.
Distribution and habitat: Eospalax muliensis sp. nov. is currently known only from the Kangwu Ranch, Muli County, Sichuan Province, China (elevational range ~3 700 m). The habitat is alpine meadow, surrounded by shrubs (Supplementary Figure S4). This species may be adapted to high-elevation habitats, and thus may occur in other alpine meadows in the southern Hengduan Mountains.
Tao Zhang, Meng-Long Lei, Hao Zhou, Zhong-Zheng Chen and Peng Shi. 2022. Phylogenetic Relationships of the Zokor Genus Eospalax (Mammalia, Rodentia, Spalacidae) inferred from Whole-genome Analyses, with Description of A New Species Endemic to Hengduan Mountains. Zoological Research. 43(3); 331-342. DOI: 10.24272/j.issn.2095-8137.2022.045
