Abstract
Recent molecular systematic studies of arvicoline voles of the genera Neodon, Lasiopodomys, Phaiomys, and Microtus from Central Asia suggest the inclusion of Phaiomys leucurus, Microtus clarkei, and Lasiopodomys fuscus into Neodon and moving Neodon juldaschi into Microtus (Blanfordimys). In addition, three new species of Neodon (N. linzhiensis, N. medogensis, and N. nyalamensis) have recently been described from Tibet. Analyses of concatenated mitochondrial (Cytb, COI) and nuclear (Ghr, Rbp3) genes recovered Neodon as a well-supported monophyletic clade including all the recently described and relocated species. Kimura-2-parameter distance between Neodon from western Nepal compared to N. sikimensis (K2P = 13.1) and N. irene (K2P = 13.4) was equivalent to genetic distances observed between recognized species of this genus. The specimens sampled from western Nepal were recovered sister to N. sikimensis in the concatenated analysis. However, analyses conducted exclusively with mitochondrial loci did not support this relationship. The occlusal patterns of the first lower (m1) and third upper (M3) molars were simpler in specimens from western Nepal in comparison to N. sikimensis from eastern Nepal and India. Twelve craniodental characters and four external field measurements were examined from specimens of N. sikimensis from eastern Nepal and India, N. irene, and Neodon from western Nepal. Neodon from western Nepal were significantly different from N. sikimensis from eastern Nepal and India in ten out of 16 characters measured and from N. irene for all characters except ear height. Specimens from western Nepal were smaller in size than N. sikimensis from Eastern Nepal and India and larger than N. irene. Together the results of the molecular and morphological analyses indicate that Neodon from western Nepal are distinct under the phylogenetic, genetic and morpho species concepts.
Highlights
The genus Neodon (Tribe Arvicolini, Subfamily Arvicolinae) was described by Horsfield [1] and was retained as a genus in early revisions [2,3,4]
Two species of Neodon are recognized as occurring in Nepal, N. sikimensis and N. leucurus [26], though the molar patterns of two specimens (NHML 541076 & NHML 662583) referred to as N. irene were illustrated by Nadachowski and Zagorodnyuk [16]
Specimens cataloged as N. irene collected from locations in Nepal are housed in the American Museum of Natural History and the Natural History Museum of London
Summary
The genus Neodon (Tribe Arvicolini, Subfamily Arvicolinae) was described by Horsfield [1] and was retained as a genus in early revisions [2,3,4]. Allen [5] recognized Neodon as a subgenus of Microtus whereas Ellerman and Morrison-Scott [6] included it in the genus Pitymys, a large and rather ill-defined genus with taxa occurring in the Palearctic and Nearctic. Gromov and Polyakov [7] considered Neodon a subgenus of Microtus whereas Corbet [8] followed the suggestion of Ellerman and Morrison-Scott [6] including Neodon in the genus Pitymys. Central Asia voles including the genera Neodon, Blanfordimys, and Phaiomys have been hypothesized to be Pleistocene relicts due to their primitive molar occlusal patterns resembling the fossil genus Allophaiomys [16].
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