Further assessment of the Genus Neodon and the description of a new species from Nepal - PubMed (original) (raw)

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

Nelish Pradhan et al. PLoS One. 2019.

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.

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Conflict of interest statement

The authors have declared that no competing interest exist.

Figures

Fig 1. Localities of specimens of Neodon examined.

Distributional boundaries of Neodon species novum (red), N. sikimensis (dotted), and N. irene (blue). Collecting localities of museum specimens of N. sikimensis (circles), N. irene (triangle), and N. species novum (squares) examined in the study, with the type locality of N. sikimensis indicated with a star. Localities of sequenced specimens of N. species novum (black squares), approximate location of specimens of N. sikimensis sequenced by Liu et al. [20, 22] (black circle), and N. irene misidentified as N. sikimensis in the FMNH (black triangle). Range shapefiles of N. sikimensis and N. irene acquired from Terrestrial Mammal dataset IUCN Red List (

https://www.iucnredlist.org/resources/spatial-data-download

). Shapefiles for Himalayan ecoregions acquired from The Nature Conservancy terrestrial ecoregion data set (

http://maps.tnc.org/gis\_data.html

Fig 2. Illustration of occlusal patterns of m1 (top) and M3 (bottom) molars of Neodon.

Illustrations derived from photos of the dentition of specimens (S1 Fig) examined by Nadachowski and Zagorodnyuk following their numbering system (see Fig 2 [16]).

Fig 3. Arvicolinae phylogenetic tree.

Bayesian tree of concatenated Cytb, COI, _Rbp_3, and Ghr genes with nodal support as Maximum Likelihood bootstraps (1000 replicates) and Bayesian posterior probability values (ML/PP; only if >50%) where an asterisk (*) refers to ML = 100 and PP = 1.00.

Fig 4. Box plots of morphometric characters.

Box plots for eight cranial, four dental, and four external field measurements comparing specimens of Neodon species novum (n = 15), N. sikimensis (n = 146), and N. irene (n = 14). Mean±SEM in red and median denoted by thick black horizontal bar. SGL = skull greatest length, SBL = skull basal length, CBL = condylobasal length, ZB = zygomatic breadth, MB = mastoid breadth, IOW = least interorbital width, SH = skull height, ABL = auditory bullae length, LMxT = length of maxillary tooth row, LMbT = length of mandibular tooth row, MM = width across upper molars, TUIB = breath across upper incisors, TBL = total body length, TL = tail length, HF = length of hind foot, and EL = length of ear.

Fig 5. Projection of canonical variates from discriminant analyses.

Includes analysis of 8 cranial (SGL, SBL, CBL, ZB, MB, IOW, SH, and ABL), 4 dental (LMxT, LMbT, M-M, and TUIB) and 4 external field measurements (TBL, TL, HF, and EL) for Neodon species novum (n = 12), N. sikimensis (n = 74), and N. irene (n = 8).

Fig 6. Pie chart of variation of molar occlusal patterns.

Comparison of first lower molar (m1) and third upper molar (M3) of Neodon species novum (n = 15) and Neodon sikimensis (n = 156).

References

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Further assessment of the Genus Neodon and the description of a new species from Nepal - PubMed (original) (raw)