Neodon linzhiensis Liu, Sun, Liu, Wang, Guo and Murphy, sp. nov
Creators: name: Liu, Shao Ying
name: Sun, Zhi Yu
name: Liu, Yang
name: Wang, Hao
name: Guo, Peng
name: Murphy, Robert W.
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Cricetidae
Neodon
Neodon linzhiensis

description: Neodon linzhiensis Liu, Sun, Liu, Wang, Guo and Murphy sp. nov
Holotype: Adult female, collected by Shaoying Liu, Yang Liu and Rui Liao on 22 August 2007. The specimen was prepared as a skin with cleaned skull and deposited in Sichuan Academy of Forestry (XZLL 02002).
Type locality: Gongbu Nature Reserve, eastern Linzhi, Xizang, China, 29.72891° N and 94.75630° E, 3890 m above sea level (a.s.l.; Fig. 1).
Measurements of holotype: Weight: 44 g; HBL: 100 mm; TL: 37 mm; HFL: 17 mm; EL: 15 mm; SGL: 26.64 mm; SBL: 24.4 mm; CBL: 25.5 mm; ZB: 14.94 mm; IOW: 3.22 mm; MB: 12.54 mm; SH: 9.42 mm; ABL: 7.42 mm; LMxT: 5.80 mm; LMbT: 5.72 mm; M-M: 5.00 mm (Table 1).
Paratypes: Sixteen specimens, skins with skulls; male specimens with glans penes. Twelve specimens (XZLL01001, Ƥ; XZLL01002, 3; XZLL01003, 3; XZLL01004, 3; GB09N188, Ƥ; GB09N189, 3; GB09N190, 3; GB09N201, 3; GB09N205, Ƥ; GB09N206, Ƥ; GB09N207, Ƥ; and GB09N211, 3) were collected from Lunang Town (29.72894° N, 94.72942° E, 3890 m a.s.l., 2 kilometers west of the type locality), Linzhi County, Xizang, China. Another specimen (XZLL02003, 3) was collected from the type locality. Three specimens (GB 081001, 3; GB 081101, Ƥ; and GB 081102, 3) from Langxian County (29.70298°– 29.74884° N; 93.3300°9– 93.35358 ° E, 3640–3770 m a.s.l.) Xizang, China.
Additional specimens. Ten specimens. Three (XZLL 02001, 3; GB09N204, 3; and GB09N210, 3, with skull broken) were from the type locality; three (XZLL 01005, Ƥ, with skull broken; XZLL 01006, juvenile, Ƥ; and XZLL 01007, juvenile, 3) were from 2 kilometers west of the type locality; four specimens (GB 080505, 3; GB 080406, Ƥ; B 081103, Ƥ; and B 081206, Ƥ, with skulls broken) came from Langxian County, China.
Geographic distribution. The new species is recorded only from Gongbu Nature Reserve, Linzhi, China (Fig. 1). The type locality consists of an abandoned field adjacent to cropland plants with highland barley (Hordeum vulgare L. var. nudum Hook f.).
Etymology. The name is derived from the type locality, Linzhi County.
Diagnosis. An arvicoline rodent with the typical palate of Microtus. The 1st lower molar has five closed triangles and six inner and five outer angles. The inner side of the 3rd upper molar of 50% specimens exhibits four angles; the remaining specimens have three. The 1st transversal loop of the 3rd lower molar lacks an outer angle, thus the 3rd lower molar exhibits only two outer angles and three inner angles. The tail is short, only 30% of head and body length. Fore and hind claws moderately developed. Frontal base of ears without long hairs. Back of hindfeet covered with short, sparse hairs. Back of toes with few hairs and plantar hairs short and sparse. Skull with very distinct temporal ridges fused to form a linear median interorbital crest. Squamosals, frontals, and parietals modified with ridges. The baculum is unique, with the proximal baculum trumpet-shaped and sturdy, the distal baculum tongue-shaped and sturdy, and the lateral bacula slightly ossified. The mean cyt b distances (p-distance) between Neodon linzhiensis and other species of Neodon are 10.9–12.6%.
Description. Generally, the holotype is black-brown in pelage. Dorsum is covered with hairs. Hairs are thin and long, about 8–10 mm. The proximal end of fur is black-grey, and the distal end is black-brown and dense over the body. Among furs, there are sparse guard hairs which were black, longer and firmer than the undercoat. The ventrum is more lightly colored than the dorsum. The ventral fur is black-gray at the base and off-white at the tip, with no guard or pile hairs; the color from the throat to belly and anus is uniform, but the tips of hairs on the ventral middle are faint yellow. The transition between the darker dorsal and lighter ventral pelage is not abrupt. The margin of lip is grey-white. The pelage of the paratypes is similar to that of the holotype.
Mystacial vibrissae are mostly white, but some are black (18–20 each side). The shortest vibrissa is about 7 mm, and the longest one is about 28 mm.
The ears project slightly above the pelage, with the rim on the front of the ears covered with dense fur; pelage is gray at the base and black-brown at the tip; the back of the ears has thin black-gray fur. The dorsal tail is blackbrown and the underside is light gray-white. The hairs of the tip of the tail are slightly long. Hairs on the forelimbs are black-gray, and the base of the hairs on the dorsal surface of the forefoot is black-gray; the tip is grey-white. The pelage on the hindlimbs is dark-gray. Hairs on the dorsal surface of the hindfoot are almost similar with those of the forefoot. The dorsal part of claws is black and ventral part is grey-white and translucent. There are five palmar pads and six plantar pads. Females have eight mammae consisting of two pectoral pairs and two inguinal pairs.
The skull is sturdy (Fig. 2 A), with the dorsal profile straight, and the brain case flattened. The nasals are broad anteriorly and narrow posteriorly. The posterior margin of the nasals is circinal, and protrudes in front of the maxilla. The posterior and anterior of the frontal bone are broad, while narrow in the middle. The interparietal bone is broad and irregularly indented, with the anterior middle part protruding to the frontal bones. Ridges in the interorbital space are very distinct; in an old specimen the two ridges syncretizes into a crest. There are two ridges behind the temporal bone and above the auditory bulla. The squamosals, frontals, and parietals are modified with ridges. The zygomatic arches are sturdy. Auditory bullae are medium-size. The incisory foramen is long and narrow, averaging 1.2 mm in width and 5.2 mm in length. The posterior palate is typical of that of Microtus, continuing as a narrow bridge, sloping dorsally to join the anterior edge of the mesopteryoid fossa, and separating the two lateral pits. Many small nutritive foramina occur on the palatine and pterygoid, and the mandibles are sturdy.
The upper incisors are narrow (TUIB = 1.91 mm) and orange in color. Molars are rootless. The 1st upper molar (Fig.2 B1 and B2) exhibits five closed triangles (two inner and three outer). The 2nd upper molar has four closed triangles (two inner and two outer), the inner triangles are large and the outer triangles are small, forming two inner and three outer angles (Fig.2 B1 and B2). In 50% of the specimens examined, the 3rd upper molar consists of a transverse prism followed by two small outer, and a larger inner, closed triangles, and a C-shaped loop, so this tooth forms four inner and three outer angles (Fig.2 B1). In other specimens, the 3rd upper molar consists of a transverse prism followed by two small outer and a larger inner closed triangles, and a Y-shaped loop, so this tooth forms three inner and three outer angles (Fig.2 B2).
The length of the lower incisors exceeds that of the concave of the mandibular condyle and the coronoid process, and is about 86% of the mandible length. The 1st lower molar (Fig. 2 B3) has five closed triangles in front of the posterior transverse space, the anterior space large and anomalistic forming two inner angles, so that this molar has six inner and four outer angles. The 2nd lower molar (Fig. 2 B3) has four closed triangles in front of the posterior transverse space, the most anterior triangle being the smallest. This molar has three outer and three inner angles. The 3rd lower molar (Fig. 2 B3) consists of three transverse lobes, of which the anteriormost has no external projection. This molar has three inner and two outer angles.
The glans penis of the new species (Fig. 3 A) is broad (Table 3). The exterior of the glans is pole-shaped and has a ventral groove. There are no outer crater papillae. The urethral lappet forks into three branches. The dorsal papilla is conical-like and as high as the outer dorsal crater. The proximal baculum is bony, broad and trumpetshaped. The distinct distal baculum also is bony and tongue-shaped, but the lateral bacular processes are only slightly ossified (Table 3).
Habitat. The specimens were collected from abandoned farmland and along the footpath of a rice field where highland barley was grown.
Comparison with other species. The new species shares the following characters with other members of Neodon: same pattern of M1, M2, M2, and M3; and same ratio of tail length to head and body length. The new species can be distinguished from its congeners by the following characters: head and body length larger than in N. irene and N. fuscus, and smaller than in N. sikimensis and N. leucurus (Table 1); first lower molar with five closed triangles (N. fuscus has four closed triangles, and the other species of Neodon only three closed triangles. Table 3); inner side of first lower molar with six angles (trait shared with N. sikimensis, but different from the other species of Neodon, which have only five inner angles); third upper molar multivariate with three or four inner angles (N. sikimensis has four inner angles and the other species of Neodon have only three. Table 3 and Fig. 2); and the skull is modified with ridges on the squamosals, temporal, frontals, and parietals (differs only from N. irene, which is void of skull ridges; Table 3). Characteristics of the five species of Neodon as newly defined are listed in Tables 1–3 and Figs. 2 and 3.
The new species shares several characteristics with the known species of Lasiopodomys. For example, they have the same structure of M1, M2, M2 and M3, and the glans penis is without outer crater papilla, and the dorsal papilla is bean-like (Yang et al. 1992). The new species can be distinguished by the length of the ear and tail, the number of the inner angles in M3 and M1 (Table 2), and the lateral bacula (Yang et al. 1992) as follows: M1 of Lasiopodomys has only three inner angles, and M3 shows only five inner angles. Lasiopodomys has a shorter ear, shorter tail length ratio, smaller skull height ratio, broader zygomatic breadth ratio, and longer forefinger claw; and the palmar and plantar possess denser hairs, and the base of front of the ears develops dense and long hairs. The lateral bacula of Lasiopodomys brandtii are cartilaginous.
Compared with Microtus, the new species is morphologically most similar to M. limnophilus, with which it shares the same pattern of M1, M2, M2, and M3, and the same ratio of the tail length to body length. However, 50% of the M3 of the new species have three inner angles, whereas M. limnophilus has four inner angles, and the first lower molar of the new species exhibits five closed triangles and six inner angles, whereas M. limnophilus has only four closed triangles and five inner angles. The results of the t -test showed significant differences in TL, ZB, MB, SH, ABL, M-M, LMxT, LMbT and LIL between both species (Appendix V).
Morphologically, the glans penis of the new species shares the following characteristics with other members of Neodon: no outer or very thin crater papillae; the distal baculum is comparatively short; the lateral bacula only slightly ossified (that of N. leucurus is cartilaginous). The new species is unique in having a trumpet-like proximal baculum and a tongue-shaped distal baculum; all other species of Neodon have a rhombic or flask-like proximal baculum and a stick-shaped or triangular distal baculum. Further, the urethral lappet of the new species has three forks, similar to that of N. sikimensis and N. fuscus, but differing from the two forks of N. irene and N. leucurus. Similar to N. sikimensis and N. leucurus, the dorsal lappet of the new species is conical shaped, but this condition differs from N. irene and N. fuscus, which consists of two forks (Fig.3; Table 3).
Intraspecific variation. Specimens of Neodon linzhiensis were collected from two localities along the Yaluzhanbu River. They formed two lineages in the cyt b gene tree. The mean uncorrected p-distance of the two lineages was 0.83% and the pairwise genetic distance of the four individuals ranged from 0.17% to 1.05%.
description: Published as part of Liu, Shao Ying, Sun, Zhi Yu, Liu, Yang, Wang, Hao, Guo, Peng & Murphy, Robert W., 2012, A new vole from Xizang, China and the molecular phylogeny of the genus Neodon (Cricetidae: Arvicolinae), pp. 1-22 in Zootaxa 3235 on pages 10-15, DOI: 10.5281/zenodo.280393