Neodon minor Wang & Liu, 2025

Wang, Xuming, Pan, Xuan, Liu, Yingxun, Murphy, Robert W., Peng, Buqing, Duan, Chao, Liao, Rui, Wang, Xin & Liu, Shaoying, 2025, Three new species of Neodon (Rodentia, Cricetidae) from Sichuan and Xizang, China, Zoosystematics and Evolution 101 (3), pp. 999-1012 : 999-1012

Neodon minor Wang & Liu sp. nov.

Note.

Unnamed clade N. sp 1

Holotype.

An adult female, field number JJSA 384 (Museum number SAF 09244 ), collected from Baoxing County, Sichuan, by Rui Liao on 2 September 2009 . The specimen was prepared as skin with a cleaned skull and deposited at the Sichuan Academy of Forestry.

Type locality.

Jiajin Mountains , Baoxing County, Sichuan, China; 30.83635°N, 102.70953°E; 3,460 m a. s. l.

Measurements of holotype.

Weight, 28 g; HBL, 92 mm; TL, 37 mm; HFL, 15 mm; EL, 13 mm; SGL, 23.62 mm; SBL, 22.31 mm; CBL, 23.26 mm; ZB, 13.31 mm; IOW, 3.22 mm; MB, 11.17 mm; SH, 8.51 mm; ABL, 6.54 mm; LMxT, 5.31 mm; LMbT, 5.28 mm; M-M, 4.52 mm; ML, 13.72 mm; and LEPILM, 7.94 mm.

Paratypes.

Twelve specimens (7 ♂♂, 5 ♀♀), skins with skulls, and male specimens with glans penis. Seven specimens (JJSA 382 [ SAF 09242 ], ♂; JJSA 383 [ SAF 09243 ], ♀; JJSA 385 [ SAF 09245 ], ♂; JJSA 386 [ SAF 09246 ], ♂; JJSA 487 [ SAF 09347 ], ♂; JJSA 491 [ SAF 09350 ], ♀; and JJSB 010 [ SAF 09374 ], ♀) from Jiajin Mountains. One specimen (BLS 001 [ SAF 09779 ], ♂) from the Balang Mountains. Four specimens (WOL 14015 [ SAF 14245 ], ♂; WOL 14033 [ SAF 14263 ], ♀; WOL 14103 [ SAF 14333 ], ♂; and WOL 14131 [ SAF 14361 ], ♀) from the Wolong National Nature Reserve. All specimens were collected by Rui Liao.

Geographic distribution.

This new species has been recorded in most areas of the Qionglai Mountains, Sichuan, China, including the Jiajin and Balang Mountains, Wolong National Nature Reserve, and Xiling Snow Mountain.

Etymology.

The species epithet was derived from its being the smallest species of Neodon . Common names: Lesser Mountain Vole, 小松田鼠 (Xiao Songtianshu).

Diagnosis.

The smallest species of Neodon , where adult HBL does not exceed 100 mm and TL comprises nearly 38 % of the HBL. Upper incisors straight, not tilting forward. Lower first molars with three closed triangles in front of posterior transverse space, five inner angles, and three outer angles. Second upper molar without posterior inner angle, with two inner and three outer angles. Third upper molar with four inner and three outer angles. Distribution of N. minor sp. nov. near to that of N. irene , but allopatric, occurring at a higher elevation. Tooth patterns similar. Skull of N. irene much larger than that of N. minor sp. nov., and the third upper molar of N. irene typically with three inner and three outer angles, while that of N. minor sp. nov. with four inner and three outer angles.

Description.

General pelage color of holotype brown, with back fur approximately 10 mm long. Proximal part of fur black-gray, while the distal parts brown, with an indistinct color boundary between the dorsal and ventral fur. Ventral fur gray-white with a black-gray base, uniform color from throat to belly and anus. Pelage of paratypes same as that of the holotype. Mystacial vibrissae mostly brown, but some black, with approximately 20 on each side. Shortest vibrissa approximately 4 mm, and longest approximately 27 mm. Ears projected slightly above pelage. A rim present on the front and entire back, with dense brown fur. Color on the top and underside of tail consistently tan, similar to dorsal fur. Hairs on the tip of tail slightly longer. Forelimb hairs were gray-white, hindlimb pelage gray-brown (Fig. 4 C 1 – C 3 ). Claws yellow-white, with long, stiff hair. Five palmar pads and six plantar pads. Females with two pectoral and two inguinal pairs of mammae. Skull sturdy (Fig. 5 C ) and straight in dorsal profile, nasal bridge slightly arched, and braincase approximately orbicular. Nasal bones broad anteriorly and narrow posteriorly. Posterior and anterior frontal bones broad but narrow in the middle. Interparietal bone broad, trapezoid-shaped. Distinct ridges in interorbital space, elderly individuals having two ridges forming a crest. Two ridges behind temporal joint above auditory bulla. Zygomatic arches sturdy. Auditory bullae medium-sized. Posterior palate typical of Arvicolinae , continuing as a narrow bridge and separating two lateral pits. Palatine and pterygoid with many small foramina. Mandibles sturdy. Upper incisors straight with lip-sides light orange. First upper molar with four closed triangles after anterior transverse space (two inner and two outer), forming three inner and three outer angles. Second upper molar with three closed triangles after the anterior transverse space (one inner and two outer), forming two inner and three outer angles. Third upper molar transverse prism-like, followed by two small outer triangles, one larger inner closed triangle, and a C-shaped loop, forming four inner and three outer angles. Lower incisors relatively long, and lip sides light orange. First lower molar with three closed triangles anterior to posterior transverse space; anterior space large and anomalistic, forming two inner and two outer angles, with five inner and four outer angles. Second lower molar with three inner and three outer angles. Third lower molar with three transverse lobes, forming three inner and three outer angles. Glans penis smaller than that of other Neodon species (Fig. 6 C ). Exterior of gland stick-shaped with a ventral groove. Outer crater papillae absent. Most specimens with urethral lappets forked into three branches, middle branch slightly lower; a few specimens with only two branches. Two shapes of dorsal papillae: most specimens with two cusps, a few with only one cusp. Proximal, distal, and lateral bacula bony. Proximal baculum slightly enlarged and spoon-shaped. Distal baculum thick and stick-shaped. Lateral baculum stick-shaped and short.

Habitat.

This species inhabited alpine shrubs and alpine meadows at elevations ranging from 3,400 to 4,300 m. It typically digs holes approximately 20 mm in diameter, usually in grass or under shrub roots.

Figures

Figure 4. Dorsal, ventral, and lateral views of N. kulakangria sp. nov. (A 1 – A 3), N. konggordous sp. nov. (B 1 – B 3), and N. minor sp. nov. (C 1 – C 3).

Figure 5. Dorsal, ventral, and lateral views of the skull and dorsal and lateral views of the mandible of N. kulakangria sp. nov. (A), N. konggordous sp. nov. (B), and N. minor sp. nov. (C).

Figure 6. Penis of N. kulakangria sp. nov. (A), N. konggordous sp. nov. (B), and N. minor sp. nov. (C). Numbered structural features are as follows: 1. penis; 2. midventral cut view of glans; 3. urethral papilla; 4. dorsal papilla. Lowercase letter structural features are as follows: a. distal baculum; b. outer crater papillae; c. outer crater; d. urethral papilla; e. ventral groove; f. glans; g. prepuce; h. body of penis; i. tip of distal baculum; j. site of dorsal papilla; k. lateral baculum; l. proximal baculum; m. the base of proximal baculum.