Biswamoyopterus gaoligongensis, Li, Quan, Li, Xue-You, Jackson, Stephen M., Li, Fei, Jiang, Ming, Zhao, Wei, Song, Wen-Yu & Jiang, Xue-Long, 2019

Li, Quan, Li, Xue-You, Jackson, Stephen M., Li, Fei, Jiang, Ming, Zhao, Wei, Song, Wen-Yu & Jiang, Xue-Long, 2019, Discovery and description of a mysterious Asian flying squirrel (Rodentia, Sciuridae, Biswamoyopterus) from Mount Gaoligong, southwest China, ZooKeys 864, pp. 147-160: 150-157

publication ID

http://dx.doi.org/10.3897/zookeys.864.33678

publication LSID

lsid:zoobank.org:pub:246FA0BE-1170-4DB6-94C7-6C24043A9C4C

persistent identifier

http://treatment.plazi.org/id/21C9D58C-EDC9-4016-8148-3F81DB51D9D3

taxon LSID

lsid:zoobank.org:act:21C9D58C-EDC9-4016-8148-3F81DB51D9D3

treatment provided by

ZooKeys by Pensoft

scientific name

Biswamoyopterus gaoligongensis
status

sp. nov.

Biswamoyopterus gaoligongensis   sp. nov.

Common name.

Mount Gaoligong Flying Squirrel. Chinese common name "高黎贡比氏鼯鼠".

Holotype.

Specimen KIZ: 034924 (field number bs1628), an adult male, skull, dried skin, baculum, and remaining body part in alcohol deposited in the Kunming Natural History Museum of Zoology, Kunming Institute of Zoology, Chinese Academy of Science (KIZ).

Type locality.

Baihualin village [25.298167N, 98.784683E], Lujiang township, Longyang County, Baoshan City, Yunnan, China. The locality is located on the eastern slope of the southern Mount Gaoligong.

Etymology.

The specific name is derived from Mount Gaoligong, the type locality of the new species and - ensis, Latin for belonging to.

Diagnosis.

Biswamoyopterus gaoligongensis   sp. nov. can be distinguished from the other two described species of Biswamoyopterus   by the following combination of traits: 1) The ear tufts at the base of the posterior margins of ears are bicolored, basally white and terminal black. The scrotum is dark brown which strongly contrasts with the yellowish-white abdominal pelage. 2) The muzzle is very short, and the zygomatic arch is distinctly expanding outward, making the outline of the skull short and wide. The outer margin of the nasal bone, the orbital margin of the frontal bone, and the post-orbital margin of the frontal bone are almost parallel to the midline of skull on the dorsal view. The central point of the posterior margin of the palatal bones lies in front of the posterior margin of M3. 3) M1 and M2 are sub-square in outline, and as large as P4. The hypoconid of P4-M2 are very developed, strongly pointed towards posterior buccal side.

Description.

Biswamoyopterus gaoligongensis   sp. nov. is a large flying squirrel (head and body length: 440 mm, tail length: 520 mm, and body mass: 1370 g) with a very developed uropatagium that extends approximately one-third of the proximal tail length in fresh specimen ( Fig. 4 View Figure 4 ). The back and upper surface of patagium are predominantly reddish brown, while the back between the shoulder and uropatagium is speckled with numerous white-tip furs that are absent from the head, shoulder, plagiopatagium, outer edge of uropatagium, limbs, and tail ( Fig. 4 View Figure 4 ). Similar to the shoulder, the head is reddish brown, but showing some yellowish grey in the crown. The ear is naked, with two bunches of long hairs (i.e., ear tufts) at the ear base, the anterior tufts are black, and the posterior tufts are basally white and terminal black. The back of each manus is reddish brown and the digits are black, while the whole pes and digits are black. The tail is cylindrical, the part beyond the uropatagium is black, and the part within the uropatagium is the same colour as the uropatagium. Throat, belly, and ventral surface of patagium are yellowish white. However, the scrotum is dark brown which strongly contrasts with the abdominal pelage.

Skull is large with a short muzzle and an expanded outward zygomatic arch, making the outline of skull short and wide ( Fig. 5 View Figure 5 ). The frontal depression is deep and postorbital processes are large and well developed. The outer margin of the nasal bone, the orbital margin of the frontal bone, and the post-orbital margin of the frontal bone are almost parallel to the midline of skull on the dorsal view. The auditory bullae are relatively large, with a honeycomb pattern of complex septae. The interpremaxillary foramen is well opened, which is not common in most flying squirrel genera. The mandible is generally similar to that of other flying squirrels. The coronoid process is less developed, only slightly higher than condylar process when the mandible is placed on a plane.

The anterior surface of incisors is pale yellow. Cheek teeth are strongly cuspidate brachyodont, with slightly pitted enamel.

Maxillary teeth: P3 is strong and unicuspid. Parastyle is prominent on P4 and dwindle on the following molars in an anterior to posterior gradient. Paracone is prominent on P4, M1, M2, and M3. Metacone is prominent on P4, M1, and M2, and indistinct on M3. Between protocone and metacone, at the exit of the middle valley of P4, M1, M2, and M3, there are two mesostyles form a projecting gutter. Protocone is prominent on P4, M1, M2, and M3. Hypocone is small, separated from protocone by a notch, distinct on M1 and M2, small on P4, and absent on M3. The anteroloph and posteroloph are indistinct on P4 and M3; distinct on M1 and M2, but they do not develop into a ridge as high as the protoloph and metaloph. A protoloph connecting the protocone with the paracone on M1, M2, and M3, and notched on P4. A metaloph connecting the protocone with the metacone on M2, interrupted by one big or two small metaconules on P4 and M1, and absent on M3.

Mandibular teeth: Four main cusps (protoconid, hypoconid, metaconid, and entoconid) are all distinct on P4, M1, M2, and M3. Mesoconid is present on the buccal side of P4, M1, M2, and M3, the notch between mesoconid and hypoconid is distinct, seems to be formed by the intense wear and tear. Mesostylid is small and fused with metaconid on P4 and M1, indistinct on M2 and M3.

Comparison.

Body size, B. gaoligongensis   sp. nov. is similar to B. biswasi   but clearly smaller than B. laoensis   (Table 1). Pelage colour becomes dark gradually from B. biswasi   to B. gaoligongensis   sp. nov. and to B. laoensis   . The back, B. biswasi   is morocco-red speckled with white, B. gaoligongensis   sp. nov. is reddish brown speckled with white, and B. laoensis   is dark reddish brown speckled with white. The belly, B. biswasi   is white, B. gaoligongensis   sp. nov. is yellowish-white, and B. laoensis   is pale orange. The tail beyond uropatagium, B. biswasi   is pale smoky grey, with a dark tip, both B. gaoligongensis   sp. nov. and B. laoensis   are black ( Fig. 4 View Figure 4 ). The ear tufts, B. biswasi   are white, B. gaoligongensis   sp. nov. are bicolour (the anterior tufts are black, and the posterior tufts are basally white and terminal black), and B. laoensis   are black ( Fig. 6 View Figure 6 ).

The muzzle of B. gaoligongensis   sp. nov. is very short, B. biswasi   is intermediate, and B. laoensis   is much longer ( Fig. 5 View Figure 5 , Table 1). As a result, the outline of skull of B. gaoligongensis   sp. nov. is short and wide, B. biswasi   is relatively short, and B. laoensis   appears long. On the dorsal view of skull, the outer margin of the nasal bone, the orbital margin of the frontal bone, and the post orbital margin of the frontal bone of B. gaoligongensis   sp. nov. are almost parallel to the midline of skull, while B. biswasi   slanted, and B. laoensis   slanted even more. The postorbital processes of B. gaoligongensis   sp. nov. and B. biswasi   are clearly larger than B. laoensis   . The preglenoid process of B. gaoligongensis   sp. nov. and B. laoensis   are almost flat, whereas that of B. biswasi   obviously protruding forward ( Fig. 7 View Figure 7 ). The sutures of frontal and squamosal bone of B. gaoligongensis   sp. nov. are bulging, while B. biswasi   and B. laoensis   are almost flat. The auditory bullae of B. gaoligongensis   sp. nov. and B. biswasi   are distinctly smaller than those of B. laoensis   . The posterior margin of the palatal bones of B. gaoligongensis   sp. nov. and B. biswasi   is concave forward, while B. laoensis   is flat. The central point of the posterior margin of the palatal bones of B. gaoligongensis   sp. nov. lies in front of the posterior margin of M3, B. biswasi   just meet, and B. laoensis   lies behind ( Fig. 7 View Figure 7 ).

The metacone and hypocone of M1 and M2 of B. gaoligongensis   sp. nov. are most developed among three species, followed by B. laoensis   , again B. biswasi   . As a result, M1 and M2 of B. gaoligongensis   sp. nov. are almost equal to P4, while those of B. laoensis   and B. biswasi   are smaller than P4. In addition, the outline of M1 and M2 of B. gaoligongensis   sp. nov. is sub-square, B. laoensis   is sub-rectangle, and B. biswasi   is sub-triangular. The hypoconid of B. gaoligongensis   sp. nov. is strongest among three species, followed by B. biswasi   , again B. laoensis   ( Fig. 5 View Figure 5 ).

Distribution.

Apart from the locality of the holotype, there are two more localities in Yunnan, China, where the Biswamoyopterus gaoligongensis   sp. nov. was photographed. These include Linjiapu (25.28693N, 98.70102E), 10 km west of the type locality; and Banchang (25.145876N, 98.796026E), 9 km south of the type locality ( Fig. 1 View Figure 1 ). Although these three localities cover the east and west slopes of Mount Gaoligong (the watershed of the Irrawaddy River and the Nu River [Salween River]), they are all restricted in a small area of southern Mount Gaoligong.

Natural history.

Little is known about the natural history of Biswamoyopterus gaoligongensis   sp. nov. The holotype was collected from evergreen broad-leaved forest at an altitude of 2,000 meters above sea level. A set of photos taken in Linjiapu showed a Biswamoyopterus gaoligongensis   sp. nov. resting on the branches of Daphniphyllum   sp. Petaurista yunanensis   , P. elegans   , and Hylopetes alboniger   were also collected in the same habitat where the holotype was collected.

Conservation status.

The limited available information suggests that Biswamoyopterus gaoligongensis   sp. nov. has a relatively low abundance. Because low-altitude forests inhabited by Biswamoyopterus gaoligongensis   sp. nov. are close to human settlements, they are vulnerable to human activities. The currently known threats are agricultural reclamation and poaching.