Eozapus wanglangensis Yang, Liu & Chen, 2025

Yang, Siyu, Xie, Fei, Zhou, Chengxin, Zhang, Zongyun, Wang, Xuming, Liu, Shaoying & Chen, Shunde, 2025, Molecular phylogeny and taxonomy of the genus Eozapus (Mammalia, Rodentia, Zapodidae) with the description of a new species, Zoosystematics and Evolution 101 (2), pp. 597-608 : 597-608

Eozapus wanglangensis Yang, Liu & Chen sp. nov.

Type material.

Holotypes: • An adult female ( SAF 191248 ) captured by Rui Liao and Xuming Wang in September 2019 from the Wanglang National Nature Reserve , Pingwu, Sichuan Province, China (32.0069 ° N, 104.0221 ° E; 2931 m a. s. l.). The study skin and skull specimens have been deposited at the Sichuan Academy of Forestry ( SAF) .

Paratypes (n = 5): • Three specimens ( SAF 181406 ♂, SAF 181457 ♀, and SAF 181458 ♀) were collected by Rui Liao, Xuming Wang, and Haijun Jiang in September 2018 from the type locality at elevations ranging from 2900 to 3200 m . • One specimen of unknown sex ( SAF 06364 ) was collected by Shaoying Liu in 2006 from the type locality . • One female specimen ( SAF 03225 ♀) was collected by Zhiyu Sun in June 2003 from Jiuzhaigou , Sichuan Province, China (33.0619 ° N, 103.8474 ° E; 3100 ma. s. l.) .

Measurements of holotype

(mm). BW = 27 g; HBL = 78.00; TL = 120.00; HFL = 28.00; EL = 13.00; PL = 21.78; SBL = 16.39; MPL = 9.97; LBO = 3.66; BB = 9.98; HB = 8.02; ABL = 5.90; UTRL = 9.61; LUM = 3.91; UMRB = 4.74; ML = 12.96; LTRL = 8.07; LLMR = 3.64; ZB = 10.09.

Etymology.

The special name “ Wanglang ” refers to the Wanglang National Nature Reserve, the type locality of the new species, known for its rich biodiversity. We suggest “ Wanglang jumping mouse ” as the English common name and “ 王朗林跳鼠 (Wang lang Lin tiao shu) ” as the Chinese common name.

Diagnosis.

Slender body, longer hindfoot, adapted for jumping. The head-body length (HBL) averages approximately half as long as the total length (TL) and is slightly shorter or longer than half the TL. The skull is smaller than that of the other two species of Eozapus . Physical characteristics include a brownish-yellow body on the back. The tail is slender and covered with sparse, short, tan hairs, and the scales are conspicuous. It is distinguished from other species based on the following features: (1) Abdominal hair coloration differs from that of the other two species of Eozapus . Compared to the pure white abdominal hairs of E. vicinus , the abdominal hairs of this species are white at the base and yellow at the tips. E. setchuanus has a brownish-yellow longitudinal stripe on the abdomen, which is absent in this species.; (2) The second lower molar (m 2) has a longitudinal deep groove, and the metalopaid is concave inward medially; (3) a distinctly depressed longitudinal groove in the middle of the third lower molar (m 3) and towards the lingual side.

Description.

Small jumping mouse with a head-body length of 65–78 mm (average 71 mm) and tail length of 120–132 mm (average 126 mm), featuring a distinctly bicolored (grayish to brown) tail above and white below (HBL / TL = 0.56). Hind foot length ranges from 28 to 30 mm (average 29 mm), with ear height measuring 12–15 mm (average 13 mm). The muzzle was light brown with a tan ring above the nasal pads. The dorsum of the body is bright rusty brown with a longitudinal brown stripe from the forehead through the eyes to below the eyes and between the ears and the base of the tail. Abdominal hair has a white base and a light-yellow tip, clearly distinguishing the coloration between the back and abdomen. The tail was slender and covered with sparse, short, yellowish-brown hairs. All four feet are beige, with shorter forefeet and elongated hind limbs and hind feet.

The skull of E. wanglangensis sp. nov. is the smallest in the genus Eozapus , measuring 21.58 ± 0.67 mm. It features a curved cranial surface with the highest point at the junction of the frontal and parietal bones. The muzzle is slender, with the anterior end of the nasal bone much longer than the anterior end of the maxillary incisors. The skull has a well-developed and pronounced sagittal crest, a wider interorbital region, slender and curved zygomatic bones, nearly parallel zygomatic arches on both sides, and small auditory bullae. Compared to other Eozapus species, the skull length (SBL) of E. wanglangensis sp. nov. is the smallest, averaging 16.22 mm.

The maxillary incisors of E. wanglangensis sp. nov. are orange-red and vertically oriented, with pronounced longitudinal grooves on their anterior margins. The premolars are small and round. The first upper molar (M 1) is larger than the second, featuring four small, equal cusps on its occlusal surface with deep concave folds on both the buccal and lingual sides. The third upper molars (M 3) are the smallest. The anterior third of the anterior margin of the first upper molar (M 1) exhibits a concave fold that divides the tooth into an anterior inner lobe, with five prominent small transverse lobes on the outer side. The second and fourth lobes are taller than the other lobes. However, the second upper molar (M 2) lacks an anterior inner lobe (Fig. 5 b 2 ). The lower molars all have four distinct medial lobe-like projections. The first lower molar (m 1) is almost the same size as the second lower molar (m 2), with one concave fold on the anterior margin and two folds on the lateral side. The second and third lower molars each have one medial concave fold. There is a distinctly depressed longitudinal groove in the middle of the third lower molar (m 3) (Fig. 5 b 6 ).

Distribution and ecology.

E. wanglangensis sp. nov. is primarily found in the Wanglang National Nature Reserve and central Jiuzhaigou County, Sichuan Province. This species inhabits forests and forest-edge grasslands at altitudes ranging from 1800 to 3100 m, preferring forests with denser shrubs and streams.

Comparisons.

E. wanglangensis sp. nov. is the smallest species of Eozapus , with a head-body length-to-total length ratio (HBL / TL) of 0.56. In comparison, E. setchuanus has an HBL / TL ratio of 0.65, whereas E. vicinus has an HBL / TL ratio of 0.61. Compared to E. setchuanus (UTRL = 10.26 ± 0.48 mm; UMRB = 5.01 ± 0.11 mm) and E. vicinus (UTRL = 9.83 ± 0.57 mm; UMRB = 4.87 ± 0.11 mm), E. wanglangensis sp. nov. exhibits smaller values for UTRL (9.51 ± 0.12 mm) and UMRB (4.80 ± 0.10 mm). Eozapus wanglangensis sp. nov. has no brownish-yellow longitudinal stripes on its chest, and its hair base is white with yellow tips on its abdomen. This species differs in that the second lower molar (m 2) is discontinuous on the mesofossette and has a longitudinal groove medially, and there is a distinctly depressed longitudinal groove in the middle of the third lower molar (m 3) and towards the lingual side.

Figures

Figure 5. Skulls and tooth comparison among species of the genus Eozapus. a. E. vicinus a 1 – a 6; b. Eozapus sp. b 1 – b 6; c. E. setchuanus c 1 - c 6 holotype; (1) ventral view; (2) upper tooth row; (3) dorsal view; (4) lateral view; (5) lower jaws; (6) lower tooth row; The red arrow indicates the position of the dental variation.