Eothenomys jinyangensis, 2019

EOTHENOMYS JINYANGENSIS SHAOYING , SP. NOV.

JINYANG CHINESE VOLE

Holotype: Adult male, field number JY0313 (museum number SAF07013), collected by Liao Rui on 26 August 2007. The specimen was preserved at the Sichuan Academy of Forestry as a skin, cleaned skull, penis and tissue. The external and cranial measurements (in millimetres) are as follows (see abbreviations under Material and methods): HBL 94.0 mm; TL 53.0 mm; HFL 18.0 mm; EL 16.0 mm; SGL 23.40 mm; SBL 21.78 mm; CBL 23.26 mm; ZB 12.26 mm; IOW 3.50 mm; MB 10.52 mm; SH 8.72 mm; ABL 6.28 mm; LMxT 4.56 mm; LMbT 4.68 mm; LM 15.35; M-M 4.26 mm; and OLLI 7.28 mm. Body mass was 22 g. The skull, dentition and mandible are shown in Figure 7A 1–A 6, A 9, and pictures of the holotype are shown in the Supporting Information ( Fig. S4A).

Type locality: Baicaopo Nature Reserve , Jinyang county, Liangshan Canton, southwestern Sichuan, China, 103.275°N, 28.700°E, elevation 3490 m. This specimen was trapped with a steel trap [Jiangxi Mouse Devices Factory ( JMDF)] in tall grassland with scattered young natural firs .

Paratypes: Forty-two specimens (22 males and 20 females). Eighteen topotype intact adult specimens (12 males and six females; field numbers: JY0221 ♂, JY0222 ♂, JY0223 ♂, JY0234 ♀, JY0235 ♂, JY0309 ♀, JY0310 ♂, JY0314 ♂, JY0315 ♂, JY0318 ♀, JY0417 ♂, JY0418 ♂, JY0423 ♂, JY0718 ♂, JY0719 ♀, JY0727 ♀, JY0729 ♂ and JY0833 ♀). Twenty-four topotype adults with skulls broken (ten males, 14 females; field numbers: JY0218, JY0219, JY0220, JY0311, JY0312, JY0316, JY0317, JY0414, JY0415, JY0416, JY0419, JY0420, JY0421, JY0422, JY0720, JY0721, JY0724, JY0725, JY0726, JY0821, JY0824, JY0827, JY0831 and JY0832).

Distribution: Currently known only from the type locality and contiguous area,> 3000 m, moist grass with sparse fir habitat.

Etymology: The species name was derived from the county, Jinyang, wherein the type locality is found. Baicaopo Natural Reserve occurs at high elevation in Jinyang County. Here, a large area of wetland supports a high biodiversity. In addition to E. jinyangensis sp. nov., the rare species Proedromys liangshanensis occurs in this reserve. The lower part of this county is facing environmental threats from farming and grazing. By naming the new species after the county, we highlight the importance of this area for conservation of endemic biodiversity.

Diagnosis: Small body and head, usually <100 mm in length (averaging 92 mm); hindfeet <19 mm. Tail averages approximately half of HBL (equal to, slightly shorter than or slightly longer than half HBL). Grey pelage on back without an abrupt transition to ventral pelage. Third upper molar usually has six inner or six outer angles, although very complex with much variation; third upper molar has five inner and five outer, or five inner and four outer angles in some specimen ( Fig. 7A).

Description: Pelage from neck to hip uniform grey; some specimens with feeble yellow or yellow-brown colour. Entire back covered with fine, long, velvet hair of approximately 10–12 mm in length; proximal part of fur black-grey and distal part grey. Scarcely any guard hairs in inner fur. Venter more lightly coloured than the dorsum, black-grey at the base and grey-white at the tip of hairs with no guard or pile hairs; some specimens with brushed grey-yellow tips. Transition between darker dorsal and lighter ventral pelage not abrupt. Margin of lip grey. Approximately 25 mystacial vibrissae on both sides, half of the hair white and other half black; shortest vibrissa ~ 5 mm and longest 28 mm.

Ears project slightly above the pelage. Front part of the ears covered with dense fur, the colour same as that of the back; back of ears covered with thinner, shorter grey fur. Tail grey on top and yellow-white below. Hair at tip of tail slightly elongated. Hair on the dorsal surface of the forefoot grey brushed with yellow. Hairs on venter of forefeet grey and longer than the dorsal hairs. Hair on dorsal surface of hindfeet yellow-white and on ventral surface of hindfeet grey. Claws white. Five palmar and six plantar pads. Females with one pair of inguinal and one pair of pectoral mammae.

Skull slender, straight in dorsal profile, with flattened brain case ( Fig. 7A). Nasal broad anteriorly narrowing posteriorly. Posterior margin of nasals rounded and protruding in front of the maxilla ( Fig. 7). Posterior and anterior of frontal broad, middle a little narrower. Interparietal broad, anterior part triangle shaped and posterior margin arc shaped ( Fig. 7A). Interorbital or temporal ridges absent. Zygomatic arches slender and middle part slightly broader. Auditory bullae moderately sized. Incisory foramen 1.5 mm wide and 4.2 mm long. Posterior palate typical of Eothenomys , ending as a thin transverse shelf without a median bony bridge ( Fig. 7A). Mandibles medium sized.

The first upper molar with four closed triangles after anterior transverse space, two inner and two outer closed triangles, and three outer and three inner angles. The second upper molar with three closed triangles after anterior transverse space, one inner and two outer closed triangles, thus forming two inner and three outer angles. The third upper molar of holotype with seven triangles and an inward ‘C-loop’, with only two triangles closed, and five inner and six outer angles. Pattern of third upper molar varies; among 41 adult specimens (excluding three adults with skulls broken), 49% have five inner and six outer angles, 7% have six inner five outer angles, 39% have five inner and five outer angles, and 5% have five inner and four outer angles ( Fig. 7A).

The OLLI is 7.24 (7.10–7.30) mm. Lower incisors relatively long, averaging 14.07 (13.84–14.32) mm, occupying 86 (84.5–87.3)% of mandible length, and exceeding concavity of mandibular condyle and coronoid process. The first lower molar ( Fig. 7) with a transverse posterior space and two pairs of triangles open and confluent to each other in front of it, the anterior of which has an inner opened triangle and a trefoil, resulting in six inner and four outer angles. Some specimens, including the holotype, with five inner and four outer angles. The second lower molar has a transverse posterior space with two opposing pairs of triangles widely open and confluent at their bases; three outer and three inner angles. The third lower molar has three transverse superimposed spaces and three inner and three outer angles ( Fig. 7A 9).

Glans penis ( Fig. 8A) pole-like and slender, with a ventral groove ( Table 6). The LG averages 3.65 mm and DG averages 1.84 mm ( Table 6). Outer crater with four obvious papillae on all sides ( Fig. 8A). Morphology of urethral lappet varies; most specimens with four forks, middle being very short; a few with three forks ( Fig. 8A 2). Dorsal papilla large and with two fore-and-aft tips ( Fig. 8A 3). Proximal baculum bony and rhombus shaped; some specimens with slightly concave base. Total length of baculum ( TLB) averages 3.70 mm; proximal baculum length ( PBL) averages 2.34 mm ( Table 6). Distal baculum also bony and stick shaped, with proximal part bulgy. Lateral bacular processes also stick shaped. Distal baculum length ( DBL) averages 1.23 mm, and lateral baculum length averages 0.87 mm ( Table 6).

Reproduction: Pregnancy ratio of adult females was ~48% in August. Two embryos usually occur in pregnant individuals, but some individuals have one.

In adult males, 42% of individuals with orchidoptosis in August.

Habitat: This species inhabits moist highland grasslands with sparse fir at elevations> 3000 m. Grass height is ~ 1.5 m and very dense. In low areas, there are grass marshes.