Biswamoyopterus sp. L35

Li, Guogang, Lwin, Ye Htet, Yang, Bin, Qin, Tao, Phothisath, Phouthong, Maung, Kyaw-Win, Quan, Rui-Chang & Li, Song, 2020, Taxonomic revision and phylogenetic position of the flying squirrel genus Biswamoyopterus (Mammalia, Rodentia, Sciuridae, Pteromyini) on the northern Indo-China peninsula, ZooKeys 939, pp. 65-85 : 65

Morphological description of Biswamoyopterus sp. L35 Table 3 , Suppl. material 2: Figure S1

Remarks.

The sample L35 from northern Laos shares the same pelage color of the tuft hair at the base of the ear and side of the neck (Figure 5 , Suppl. material 2: Figure S1) with the Biswamoyopterus laoensis specimen (NUoL FES. MM.12.163) from central Laos. However, specimen M644 from northern Myanmar shares some key characters that have been used to distinguish the three known species from each other (Figures 4 - 7 , Table 3 ): its large body size and long muzzle are similar to B. laoensis (NUoL FES. MM.12.163) from central Laos; the coloration of venter, tail, and ear tufts could pertain to either B. biswasi (specimen ZSI 20705) from northeastern India or B. gaoligongensis (specimen KIZ 034924) from southwestern China, which are very similar.

Phylogeny and genetic divergence.

Maximum Likelihood and Bayesian Inference analyses of the combined sequences of nuclear gene IRBP (1070 bp), mitochondrial 12S (823 bp), and 16S (535 bp) ribosomal DNA recovered similar tree topologies. The results showed that Eupetaurus , Aeromys , and Biswamoyopterus (sample M644 from Putao, northern Myanmar, and L35 from Louang Namtha, northern Laos) as a reciprocally monophyletic clade (Figure 8 ). Within this clade, Aeromys and Biswamoyopterus form sister groups with strong support (Figure 8 ).

For the nuclear gene IRBP, the range of original intergeneric (14 genera excluding the genus Biswamoyopterus ) variation was 0.51-5.47% (Table 4 ). The genetic distances between Biswamoyopterus and other genera ranged from 1.57 to 5.27% (Table 4 ), which is greater than many intergeneric variations, such as 0.51% for Aeretes and Trogopterus , 1.46% for Belomys and Pteromyscus , and 1.46% for Pteromyscus and Trogopterus . In the genus Biswamoyopterus , the genetic distance between M644 and L35 was 0.09%, which is smaller than the range of other interspecific variations (0.51-5.45%), close to 0.13% for intraspecific variations of Pteromyscus pulverulentus .

For the mitochondrial 16S ribosomal DNA sequences, the range of original intergeneric variation was 2.9-14.6% (Table 5 ). The genetic distances between Biswamoyopterus and other genera ranged from 5.2 to 12.8% (Table 5 ), which is greater than some intergeneric variations, such as 2.9% for Aeretes and Trogopterus . In the genus Biswamoyopterus , the genetic distance between M644 and L35 was 0.6%, which is really much smaller than the range of other interspecific variations (2.9-14.6%), close to 0.4% for intraspecific variations of Petaurista philippensis , and the same as 0.6% of Pteromys volans .

Figures

Figure 4. Comparison of skins of all known Biswamoyopterus specimens A, B B. biswasi, ZSI 20705 C, D B. gaoligongensis, KIZ 034924 A-D were derived from Li et al. (2019) E, F B. laoensis, NUoLFES. MM. 12.163, from Sanamxay et al. (2013) G, H Biswamoyopterus sp. M 644 from this study.

Figure 5. Comparison of ear tufts of all known Biswamoyopterus specimens. The red arrow indicates the anterior tufts, and the yellow arrow indicates the posterior tufts A B. biswasi, ZSI 20705 B B. gaoligongensis, KIZ 034924 A, B were derived from Li et al. (2019) C B. laoensis NUoL FES. MM. 12.163 from Sanamxay et al. (2013) D Biswamoyopterus sp. M 644 from this study.

Figure 7. The posterior margin of the palatal bones relative to the posterior margin of M 3 (dotted line) and shape of the preglenoid process (arrow) of all known Biswamoyopterus specimens A B. biswasi, ZSI 20705 B B. gaoligongensis, KIZ 034924) A, B were derived from Li et al. (2019) C B. laoensis, NUoL FES. MM. 12.163, from Sanamxay et al. (2013) D Biswamoyopterus sp. M 644 from this study.

Figure 8. Bayesian Inference and Maximum Likelihood inference tree (GTR + G + I model) of flying squirrels based on combined mitochondrial and nuclear DNA data. Numbers on branches indicate posterior probability in BI and bootstrap support from ML.