Eothenomys shimianensis, 2019

EOTHENOMYS SHIMIANENSIS SHAOYING , SP. NOV.

SHIMIAN CHINESE VOLE

Holotype: Adult male, field number SHM15004 (museum number: SAF15109), collected by Shaoying Liu on 31 July 2015. Holotype deposited at Sichuan Academy of Forestry as a skin, cleaned skull, penis and tissue. The external and cranial measurements (in millimetres) are as follows (see abbreviations in Material and Methods): HBL 95.0 mm; TL 37.0 mm; HFL 17.0 mm; EL 12.0 mm; SGL 25.21 mm; SBL 23.97 mm; CBL 25.18 mm; ZB 14.26 mm; IOW 4.44 mm; MB 11.33 mm; SH 9.64 mm; ABL 6.56 mm; LMxT 5.77 mm; LMbT 5.71 mm; LM and M-M 5.19 mm. Body mass was 24 g. The skull, dentition and mandible are shown in Figure 6C 1–C 3, C 8, and pictures of the holotype are shown in the Supporting Information ( Fig. S4D) .

Type locality: Liziping National Nature Reserve, Shimian County, Yaan , southwestern Sichuan (28.93888°N, 102.24837°E; elevation 2390 m). This specimen was trapped with large steel trap (made by JMDF) in dense grassland bordering an alder plantation and surrounding broadleaf deciduous forest with abundant bamboos GoogleMaps .

Paratypes: Eight specimens (four males and four females). Three intact adults (one male and two females): SHM 15005 ♀ topotype; NYH02 ♂ from Nanyahe River in Shimian County, Sichuan (28.67473°N, 101.61008°E; elevation 2238 m); and SMLZP02005 GoogleMaps ♀ from 1 km northeast of the type locality. Five adult specimens (three males and two females) with broken skulls: NYH01 ♂ from Nanyahe River of Shimian County; and SMLZP02004 ♂, SMLZP02006 ♂, SMLZP02007 ♀ and SMLZP02008 ♀ from 1 km northeast of type locality (elevation 1850 m).

Distribution: Known only from Liziping Nature Reserve and both sides of Nanyahe River, Shimian County, Sichuan.

Etymology: The new species is named for Shimian County, where the type locality, Liziping Nature Reserve, is located. Eothenomys shimianensis sp. nov. occurs on both sides of the Nanyahe River in Shimian County at very low elevations, ranging from 2200 to 2600 m. Liziping Nature Reserve is located on the upper reaches of the Nanyahe River. This area faces very serious threats from road and tourism. By naming this new species for Shimian County, we highlight that this endemic species needs protection.

Diagnosis: Medium body and head, ~ 100 mm in length; hindfeet <20 mm. Compared with other species of subgenus Eothenomys, TL / HBL equal to that of E. fidelis , but measurements of the new species are much smaller than those of E. fidelis ; TL / HBL of new species longer than those of E. m. colurnus and E. melanogaster , shorter than those of E. cachinus , E. eleusis and E. miletus . Pelage on back yellow-brown. Palate similar to that of other species of Eothenomys ( Fig. 6A). Third upper molar with four inner and three outer angles ( Fig. 6A). Baculum of new species distinct; proximal baculum flask-like, and urethral lappet also unique ( Fig. 9A).

Description: Pelage (summer) from neck to hip uniform, with base of hairs grey and distal area yellow-brown, ~ 7.5 mm long. Nose region, top of head and around eyes grey-black mixed with a few yellow-brown hairs. Ventral hairs grey-black at the base, with a weak yellow-brown tip. Gradual transition between darker dorsal and lighter ventral pelage. Approximately 25 mystacial vibrissae on both sides, black-grey in colour, and tips of long mystacial vibrissae (> 15 mm) white; shortest vibrissa ~ 5 mm and longest 24 mm.

Ears project above pelage; 4 mm margin of front part of the ears covered with dense black fur; lower part and area surrounding the auditory meatus almost without fur; back of ear covered with dense, short, black hairs. Dorsal part of tail grey-black, ventral part grey-white, and dorsal hairs slightly longer. Dorsal hairs on forefoot (tarsus metatarsus to wrist metacarpus) grey-black, ventral forefoot and hindfeet with same colour. Claws yellow-white. Six palmar and five plantar pads. Females with one pair of inguinal and one pair of pectoral mammae.

KEY TO SUBGENERA EOTHENOMYS AND ERMITES 1. First upper molar with 4 inner triangles: subgenus Eothenomys ............................................................. … 2

First upper molar with three inner triangles; tail at least half of HBL; HBL averages <115 mm; skull length averages <27.5 mm; variable structure of third upper molar complex: subgenus Ermites ............. 8 2. HBL averages> 105 mm ….............................................................................................................................. 3

HBL averages <105 mm ................................................................................................................................. 4 3. TL longer than half of HBL............................................................................................................ E. cachinus

TL shorter than half of HBL...........................................................................................................… E. fidelis 4. TL averages> 40% of HBL.............................................................................................................................. 5

TL averages <40% of HBL.......................................................................................................................... … 7 5. HBL small, averaging ~ 95 mm, TL averaging ~45% of HBL.......................................................… E. eleusis

HBL large, averaging ~ 100 mm ...................................................................................................................... 6 6. TL averages ~43.5% of HBL............................................................................................................. E. miletus

TL averages ~41% of HBL................................................................................................... … E. shimianensis 7. Distributed south of Yangzi River ................................................................................................... E. colurnus

Distributed north of Yangzi River .......................................................................................... E. melanogaster 8. HBL averages ≥ 100 mm ................................................................................................................................. 9

HBL averages <100 mm ............................................................................................................................... 11 9. HBL > 110 mm, TL averages ~60% of HBL............................................................................ … E. tarquinius

HBL averages ~ 100 mm ............................................................................................................................ … 10 10. TL averages ~55% of HBL.............................................................................................................. E. hintoni

TL averages ~50% of HBL................................................................................................... E. luojishanensis 11. The third upper molar of> 50% of specimens with six inner or six outer angles; grey pelage on back without an abrupt transition to ventral pelage; glans penis averages <3.7 mm ................. E. jinyangensis

The third upper molar of> 50% specimens with five inner and four outer angles; abrupt transition in colour between dorsal and ventral pelage; brown back; glans penis averages> 4.2 mm ................... E. meiguensis

Dorsal profile of skull cambered ( Fig. 6A), with highest point on frontal between interorbitals. Nasal broad anteriorly, narrowing posteriorly; posterior margin of nasals straight and relatively short, not reaching suture between maxilla and frontal ( Fig. 6A). Posterior and anterior of frontal broad, middle a little narrower. Interparietal broad, quinquangular ( Fig. 6A). Interorbital ridges absent, but with squamosal ridge from the middle to temporal fossa. Zygomatic arches strong, with broader middle part ( Fig. 6A). Auditory bullae relatively small, average 6.5 mm, with welldeveloped paraoccipital process. Posterior palate typical of Eothenomys , ending as a thin transverse shelf without a median bony bridge ( Fig. 6A). Mandibles medium sized.

Upper incisors medium and orange. Molars rootless. The first upper molar with three outer and four inner angles, second with three inner and three outer angles, and third with four inner and three outer angles ( Fig. 6A6).

The OLLI is 6.96 (6.37–7.44) mm on average. Lower incisors relatively long, markedly exceeding the concavity of the mandibular condyle and coronoid process. The first lower molar ( Fig. 6A 7) has five inner and four outer angles, second has a transverse posterior space with two opposing pairs of triangles widely open and confluent at their bases and three outer and three inner angles, and third lower molar has three transverse superposed spaces and three inner and three outer angles ( Fig. 6A 7).

Glans penis ( Fig. 9A) pole-like and relatively sturdy, with ventral groove ( Table 5). The LG averages 4.3 mm and DG averages 2.2 mm ( Table 5). Outer crater with three obvious papillae on all sides ( Fig. 9A). Urethral lappet very distinct, with three forks, and all forks tend to divide into two forks ( Fig. 9A 2). Dorsal papillae cone-like, with two tips ( Fig. 9A 3). Proximal baculum bony and flask shaped. The TLB is 4.1 mm and PBL 2.6 mm ( Table 5). Distal baculum also bony and stick shaped, with bulgy proximal part. Lateral bacular processes stick shaped. The DBL is 1.3 mm and LBL is 1.1 mm ( Table 5).

R e p r o d u c t i o n: I n e a r l y J u l y, 5 0 % o f a d u l t E. shimianensis had orchidoptosis, but at this time no females were pregnant. In late July, the pregnancy ratio of adult females was ~33%.

Habitat: This species inhabits moist broadleaf forest at low elevations (<2400 m), at ~ 2200 m. The understorey consists of bamboo, with 20% coverage. Grass height ~ 40 cm, with 40% coverage. Soil very soft, sand abundant, surrounded with boulders. Humus ~ 5 cm in depth.