Further assessment of the Genus Neodon and the description of a new species from Nepal

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.

A mitochondrial genome phylogeny of voles and lemmings (Rodentia: Arvicolinae): evolutionary and taxonomic implications

“…Another significant finding is the more clear assignment of Iberomys cabrerae and Agricola agrestis, both species conventionally assigned to Microtus [1], but whоse position at the molecular trees within the Arvicolini tribe was always uncertain. The tendency for clusterization of A. agrestis and Blanfordimys, though without support was shown earlier [9,12,15,17,18]. In the paper where both I.…”

“…1857 (from Western Europe to Siberia). It is important to note that trees uniting Nearctic "Microtus'' species in one cluster were obtained in various studies [12,15,17,18], but for the first time this cluster receives robust support, justifying the genus level status under the name Mynomes.…”

“…Phylogeny of Arvicolinae has been explored using both morphological and genetic methods, allowing comparisons of reconstruction from different datasets for further cross-validation. Application of molecular phylogenetic methods resulted in a series of revisions of phylogenetic relationships and taxonomic structure of several genera and species [3][4][5][6][7][8][9][10][11][12] and references therein. Reconstruction of Arvicolinae phylogeny using nuclear genes GHR and LCAT demonstrated three successive waves of adaptive radiations in the evolutionary history of the group [7].…”

“…The third radiation wave included formation of the steppe lemmings (Lagurini), mole voles (Ellobiusini) and the richest species group -Arvicolini [7]. The branching order both within the first and the last radiation waves also remained unresolved since all attempts to untangle complex phylogenetic relationships within subfamily were made with the use of only a few mitochondrial or nuclear markers, or the study included an insufficient number of taxa in the analysis [3,5,7,9,10,[12][13][14][15][16][17][18].…”

“…To date, this is the most comprehensive dataset aimed at the revision of the Arvicolinae phylogeny considering almost all recent genera represented by nominal species. While the monophyletic origin of Arvicolinae has always been considered indisputable, previous attempts to resolve phylogenetic relationships within the subfamily using either morphological analysis or combinations of mitochondrial and nuclear markers yielded in several hard polytomies[13] or conflicting topologies[3,[5][6][7]9,12,18,73,74]. The more taxa and more markers were considered in the analysis, the better resolution for the nodes marking major tribes within Arvicolinae has been obtained[7,17,18].…”