Myotis flavus Shamel 1944

Jiang, Tinglei, Sun, Keping, Chou, Chenghan, Zhang, Zhenzhen & Feng, Jiang, 2010, First record of Myotis flavus (Chiroptera: Vespertilionidae) from mainland China and a reassessment of its taxonomic status, Zootaxa 2414, pp. 41-51 : 46-50

Myotis flavus Shamel 1944

Myotis flavus Shamel 1944 ; type specimen, National Museum of Natural History (NMNH) 239908; adult ♀, remainder in fluid, skull removed. The type specimen was collected under a grove of trees with large leaves and lilac-like flowers in Jul 1923 at Enri in Formosus .The bat hanged head downwards from the stem of a leaf. Its colour was light yellow, the wing being variegated with orange and brown ( Shamel 1944).

New materials. JX- 07X-20, adult, male, collected at Shiyan cave (114°12΄E, 26°36΄N; 1058 m) in Liping village of Jinggangshan Natural Reserve of Jiangxi Province in mainland China by TingLei Jiang and KePing Sun in September 2006. Fur specimen (No. JX- 07X-20) was deposited at Northeast Normal University, China.

Description and taxonomic notes. For Myotis species from mainland China, this is a medium to large size Myotis with a forearm length of 48.5 mm ( Table 3 )(52.5 mm in Shamel 1944), which is within the range (45 – 55 mm) given by Lin et al. (2005). The bases of the dorsal and ventral pelage are grayish white with their tips golden yellow and pale yellow, respectively ( Fig. 2 a). Light brown bands exist around the digits of the wings. There are no black edges on the upper margin of the auricles, around the nostrils, thumbs, toes and the end of the tail ( Fig. 2 a and Fig. 2 b). This clearly differs from M. rufoniger ( Bates & Harrison 1997) , M. watasei ( Lin et al., 2005) and M. tsuensis ( Yoshiyuki 1989) . The tragus is narrow and tapering towards a bluntly-pointed tip. The nose and chin are bare of long hairs for a distance of about 5 mm from tip, but the remainder of the face is well haired ( Fig. 2 b), which corresponds to those specimens described in Shamel (1944). Metacarpals are considerably shorter than the forearm, and the third, fourth, fifth metacarpals were 91.2%, 88.6% and 90% of forearm length, respectively ( Table 3 ). The wings are attached to the base of the phalanx of the outer metatarsal of each foot. Tail vertebrae extend 2.5 mm beyond the interfemoral membrane.

The greatest antero-posterior length of the skull is 18.3 mm ( Table 3 )(19.5 mm in Shamel, 1944). The skull has the forehead region strongly concave ( Fig. 3 c). The sagittal crest is well defined anteriorly but the lambdoid crest is inconspicuous ( Fig. 3 a). The joint between the supraoccipital and foramen magnum is round and protruding downwards. The supraoccipital is slightly orbicular and plump ( Fig. 3 c). The upper incisors become gradually larger from the inner to the outer teeth, and the canine is well developed ( Fig. 3 b). The upper middle premolar (P3) site is completely within the upper tooth row, whereas in M. rufoniger and M. watasei , P3 is usually only partially within the tooth row of the upper jaw ( Shamel, 1944). The upper anterior premolar (P2) and the upper posterior premolar (P4) are not in contact with each other; P3 is not visible when the tooth row is viewed externally, but is visible from a buccal view, which is same included in Shamel (1944). P3 extends its tip barely above the level of the cingulum on P2 ( Fig. 3 c). The anterior and middle upper molars have distinct W- shaped ridges, and the posterior upper molar is half reduced ( Fig. 3 b). The crowns of the second and third lower incisors divide into four leaflets. The first lower incisor is prolate, and the incisors are aligned forming a convex arch ( Fig. 3 d). P3 is set inward, but visible from the outside of the tooth row, and the cusp is more slender and pointed than in P2 and about half its height ( Fig. 3 c).

The baculum of the sample JX- 07X-20 is generally Y-shaped, but slightly ( Fig. 4 a). Proximal and distal ends concave at its central portion, and its ventral surface is not deeply fluted. Total length is 0.975 mm and maximum basal width is 0.575 mm. However, the baculum of M. formosu s from Jilin province clearly differs from that of the sample JX- 07X- 20 in having a concavity only in its proximal end and showing a deeply fluted ventral surface ( Fig. 4 b). In addition, the size of the baculum of M. formosu s (total length 0.8 mm, maximum basal width 0.575 mm.) is slightly smaller than that of JX- 07X-20.

Definitions follow those given in Bates and Harrison(1997).

Echolocation. The echolocation calls of individual JX- 07X-20 are short, broadband frequency modulated signals with a dominant fundamental harmonic. The mean value for the frequency containing the maximum energy is 43.91 kHz, with a range of 41.0 – 46.2 kHz (n = 22).

Discussion. When describing M. flavus, Shamel (1944) indicated that from M. rufoniger and M. watasei in body size and dental characteristics. Chou (2004) also distinguished M. flavus from M. watasei . In the present study, M. flavus is found to be different from M. formosus in coloration, skull and dental characteristics. In addition, differences in baculum morphology indicate a potential for the occurrence of reproductive isolation between M. flavus and M. formosus ( Wu et al., 2008) .

Relatively inexpensive and rapid DNA sequencing techniques have given biologists a new tool for detecting and differentiating morphologically similar species ( Bickford, et al., 2007). We took advantage of this by analyzing the mtDNA cytb gene, which showed that our specimen JX- 07X-20 differed by 0.61% from M. flavus from Taiwan (Table 2) which most likely corresponds to a divergence of intraspecific level. This genetical similarity supported the result of our morphological identification of this specimen. In contrast, it was surprising to see that the divergence values between M. flavus and other M. formosus specimens were so much larger (15.53–16.67 %) and even higher than the other interspecific divergences (Table 2). Genetic distances over 5% at cytb are generally considered to indicate the existence of cryptic taxonomic diversity, and values exceeding 10% in bats are indicative of species-level divergence ( Baker & Bradley 2006). Moreover, our phylogenetic analysis shows that M. formosus and M. flavus are not sister taxa (Fig. 1). Hence, we consider M. flavus to be a distinct species and different from M. formosus . In addition, the phylogenetic grouping of and sequence similarity between M. watasei and M. formosus from mainland China strongly suggests that M. watasei is synonymous with M. formosus .

Distribution and ecological notes. So far, M. flavus is only known from Taiwan ( Lin et al., 2005; Shamel 1944). The present report gives the first confirmed account of this species from mainland China. Our specimen JX- 07X-20 was captured at Shiyan cave in Liping village of Jinggangshan Natural Reserve of Jiangxi Province in China where the average temperature and mean rainfall are 14 °C and 1865 mm per year, respectively, resulting in a subtropical wet climate. The collection site is dominated by a forest consisting of Phyllostachys heterocycla , Cunninghamia lanceolata , Schima uperba and P. heterocycla . The other bat species roosting in the same cave were Rhinolophus affinis , R. pearsoni , R. macrotis , Hipposideros armiger , M. davidii and M. formosus .

Figures

FIGURE 2. Photographs of specimen JX- 07 X- 20, a: ventral view; b: lateral view of the head and neck.

FIGURE 3. Different views of the skull of specimen JX- 07 X- 20, a: dorsal view of cranium; b: ventral view of cranium; c: lateral view of cranium and mandible; d: front view of mandible.

FIGURE 4. Differences of baculum morphology between sample JX- 07 X- 20 and Myotis formosus from Jilin province, mainland China. JX- 07 X- 20 (a) and Myotis formosus (b). Scale: 0.5 mm.

Tables

TABLE 3. Characteristic comparison of external and cranial morphology between specimen JX- 07 X- 20 (3) and the holotype (Ƥ) of Myotis flavus Shamel, 1944. Measurements are in mm and body mass is in g.

Variable	JX-07X-20	Holotype (NMNH: 239908)
Length of head and body (LHB)	51	50.5
Forearm length (FA) Third metacarpal length (3MET)	48.5 44.22	52.5 47.5
Fourth metacarpal length (4MET)	42.96	–
Fifth metacarpal length (5MET) Tibia (TIBIA)	43.16 23.56	45.4 24.5
Length of hind foot (HF)	12.44	12.8
Ear length (E) Body mass (W)	15.5 13.4	18 –
The greatest antero-posterior length of the skull (GLS)	18.3	19.5
Condylobasal length (CBL) Zygomatic width (ZW)	17.14 11.6	17.2 11.5
Maxillary toothrow length (C–M3)	7.06	7.5
Mandibular toothrow length (C–M3) Interorbital breadth (IOB)	7.62 4.57	8.2 4.5
Braincase height (BCH)	7.46	7.6
Braincase width (BCW)	8.48	8.5