Murina yuanyang Mou, Qian, Li, Li, Luo & Li, 2024, sp. nov.

Murina yuanyang sp. nov. Holotype: Field number KIZ20230424, adult female, collected on 21 May 2023. The mitochondrial COI nucleotide sequence was submitted to GenBank under accession number PQ179689. Type locality: Pinghe, Xiaoxinjie Town, Yuanyang County, Yunnan Province, China (22.990097 ◦ N, 102.990097 ◦ E, 2434 m). Paratype: Field number KIZ20230450, adult female, collected in Pinghe, Xiaoxinjie Township, Yuanyang County, Yunnan Province, China (22.990097 ◦ N, 102.990097 ◦ E, 2434 m) on 22 May 2023. Field number KIZ20230415, adult male, collected in Pinghe, Xiaoxinjie Township, Yuanyang County, Yunnan Province, China (22.991851 ◦ N, 103.002188 ◦ E, 2412 m) on 21 May 2023. The mitochondrial COI nucleotide sequence of KIZ20230415 was submitted to GenBank under accession number PQ179688. Etymology: The name yuanyang refers to the type locality of the species. Measurements: Measurements of the type specimen are shown in Table 4. Diagnosis: Small-sized Murina species, FA 27.66–30.51 mm and GTL 13.44–14.16 mm (Table 4). Elongated tubular nostrils; third, fourth, and fifth finger metacarpals roughly equal in size; tail vertebrae slightly free at tip; plagiopatagium attached at about one-third from base of claw to base of toe, near base of claw (Figure 2). Fur on back glossy, overall dark golden with deep brown, with clearly demarcated color bands; ventral fur gray-white, with golden color on both sides of chest (Figure 2). Sagittal crest absent, lambdoidal crest not prominent (Figure 3); in lateral view, skull appears slightly elongated with slightly oval braincase, gradually rising with gentle slope from snout to cranial vertex (Figure 3 (A3,B3)); palatine wide without distinct concavity (Figure 3 (A2,B2,C2)). I 2 located in front of I 3, clearly visible from side; noticeable gap between I 3 and C 1; height of P 2 less than half that of C 1 and P 4 (Figure 3 (A3,B3,C3)); crown area of P 2 slightly smaller than that of C 1, less than half crown area of P 4; mesostyle of M 1 and M 2 slightly developed, M 3 reduced (Figure 3 (A2,B2,C2)). C 1 slightly higher than P 4, P 2 significantly lower than C 1 and P 4. Basal area of C 1 similar to P 4 and more than twice basal area of P 2. Lower molars belong to nyctalodont type (Figure 3 (A5,B5,C5)). Description: Body: Small-sized Murina species, HB 31.37–36.34 mm, WT 3.4–4.7 g, FA 27.66–30.51 mm, GTL 13.44–14.16 mm (Table 4). Nostrils tubular, opening sideways and relatively long (Figure 2). Snout darker than nostrils. Ear length 11.85–14.77 mm, overall shape oval, upper part forms rounded arch, not pointed, deep gray in color, color at base slightly lighter than upper part, approaching gray-white. Ear tragus long and pointed, vertical on inside, curved outwards on outside, narrow at top and wider at bottom, reaching approximately half height of ear. Third, fourth, and fifth metacarpals approximately equal in length, second metacarpal slightly shorter than third, fourth, and fifth. Tail 23.89–31.58 mm (Table 4), shorter than head–body length, slightly free at tip (Figure 2). Plagiopatagium attached at about one-third from base of claw to base of toe, near base of claw (Figure 2). Fur: Dorsal fur of holotype dark gold mixed with deep brown throughout, with four distinct bands of color on hairs. Base dark brown, middle light brown, upper-middle part with narrow dark brown or blackish brown band, top yellow-brown, sometimes golden yellow. Overall color of back appears slightly mottled and uneven. Short golden hairs on forearms and sparse yellow-brown hairs on interdigital membranes. Ventral side gray-white throughout, with base of hairs dark gray to gray and top gray-white. Neck and anal region whiter, with slight golden color on sides of chest. Relatively sparse gray-white hairs with slight sheen on interdigital membranes. Facial hair short, gray-brown mixed with golden yellow. Other specimens exhibit slight variations in dorsal fur color, appearing golden or yellowish, with distribution and characteristics of ventral and other fur similar to holotype (Figure 2). Skull: Overall skull relatively small, GTL 13.44–14.16 mm. Sagittal crest absent, lambdoid crest prominent. In dorsal view, braincase almost circular; zygomatic arches weak and slender, gradually widening from front to back, with widest point at root of zygomatic arch; posterior margin of skull slightly prominent; slight downward concavity in middle from snout to frontal region. In lateral view, skull appears slightly elongated with slightly oval braincase; height from snout to parietal shows upward trend, with gradually increasing slope from snout to frontal, and gradually decreasing slope from frontal to parietal, resulting in slight depression between snout and frontal, with slight protrusion at frontal; zygomatic arch rises gradually from anterior to posterior. In ventral view, palatine wide without any obvious concavity, ending at midpoint of C 1; basisphenoid pits tear-drop shaped, extending posteriorly to anterior half of cochlea. Mandible 8.09–8.69 mm. In lateral view, almost straight between coronoid process and condyle, without any depression, slight concavity between condyle and angle; angle short and wide, lower surface of the mandibular dentary forms obvious depression in front of angle; mental foramina clearly visible (Figure 3). Dentition: Dental formula: I 1 2 3 − 2 3 C 1 1 PM − 2 − 4 − 2− 4 M = 34. In maxilla, I 2 positioned in front of I 3, I 2 clearly visible in lateral view; crown area of P 2 slightly smaller than that of C 1, less than half crown area of P 4; species belongs to ‘s uilla -type’ based on these characteristics. Upper tooth rows converge slightly anteriorly, with PWC 1 C 1 1.42–1.78 mm and PWM 3 M 3 2.63–2.86 mm. I 2 and I 3 heights approximately equal, with crown area of I 2 approximately half that of I 3. I 2 with two cusps, smaller secondary cusp located behind primary cusp. Posterior external face of I 2 in contact with anterior internal face of I 3, with noticeable gap between I 3 and C 1. C 1 and P 4 heights approximately equal, C 1 slightly elongated and lacking secondary cusps, P 4 wider. C 1 appears slightly circular when viewed from occlusal perspective, with crown area less than half that of P 4. P 2 smaller and compressed, wider than long, distinctly oval-shaped, height close to half that of C 1 and P 4. Mesostyle of M 1 and second upper molars (M 2) not well developed; paracone, metacone, and protocone well developed, with metacone slightly higher than paracone; trigon basin open and talon well developed, with antero-external valley area significantly smaller than that of postero-external valley. M 3 reduced, with only parastyle, paracone, and protocone. Single commissure connecting parastyle and paracone. In mandible, first, second and third lower incisors (I 1, I 2, and I 3) tricuspid and of equal size, but outer cusp of I 3 relatively less distinct; slight overlap of outer cusps of I 1, I 2, and I 3; C 1 contains pointed cusp on anterior inner margin, which touches outer cusp of I 3, making C 1 slightly higher than I 3 in lateral view, with gradual increase in height from I 1 to C 1. C 1 slightly higher than P 4, P 2 significantly lower than C 1 and P 4. Basal area of C 1 similar to P 4 and more than twice basal area of P 2. In lateral view, trigonid of M 1 and lower second molar (M 2) and M 3 clearly tricuspid, with height of metaconid and paraconid approximately two-thirds that of protoconid; talonid of M 1 and M 2 bicuspid, with entoconid and hypoconid clearly separated from trigonid and lower than metaconid and paraconid, with heights approximately equal to metaconid and paraconid. Talonid of M 3 reduced. Lower molars nyctalodont type, with entoconid and hypoconid connected by postcristid (Figure 3). Comparisons: Based on its dentition, Murina yuanyang sp. nov. clearly belongs to the ‘ suilla -type’ (maxillary toothrows clearly convergent anteriorly; I 2 anterior to I 3; I 2 clearly visible from lateral view; crown area of P 2 half that of P 4) and can be distinguished from all species in the ‘c yclotis -type’. Based on the reconstructed phylogenetic tree, Murina yuanyang sp. nov. formed a monophyletic group with M. chrysochaetes and was distantly related to other species. Therefore, our comparison focuses primarily on species closely related in the phylogenetic tree and on ‘ suilla -type’ species lacking COI sequences. Comparison with M. chrysochaetes: At the molecular level, Murina yuanyang sp. nov. is most closely related to M. chrysochaetes, but exhibits some differences in morphology and cranial structure. Measurement data for FA and TIB show that Murina yuanyang sp. nov. is slightly larger in body size than M. chrysochaetes, and the HB, TL, E, and HF of the female specimens also showed longer HF and E and significantly different HB and TL ratios (HB/TL ratios were 1.23 and 1.67, respectively) compared with IEBR-M6020 and S186699 (both female). In terms of skull size, both male and female Murina yuanyang sp. nov. are slightly smaller than Murina chrysochaetes (values of STOTL, GTL, CBL, ZYW, BCW). From PWC 1 C 1 /PWM 3 M 3 and C 1 C 1 W/M 3 M 3 W, the values of male Murina yuanyang sp. nov. are 0.59 and 0.67, respectively, and female are 0.60 and 0.69, respectively, while the values of S186699 (female) are 0.66 and 0.74, respectively, which is consistent with the observation from the specimen comparison that the maxillary teeth of Murina yuanyang sp. nov. converge more anteriorly than the holotype of Murina chrysochaetes. The value of CPH shows that Murina chrysochaetes has a higher coronoid process. In terms of external morphology, Murina yuanyang sp. nov. has longer tubular nostrils. On the dorsal side, Murina yuanyang sp. nov. is generally dark gold mixed with deep brown, with four color bands on the back, while M. chrysochaetes has a mixture of black and gold stripes and tricolored fur on the back [18]. On the ventral side, Murina yuanyang sp. nov. show