Myotis hayesi, Csorba & Furey, 2022

Csorba, Gábor & Furey, Neil M., 2022, From Greener Times: A New Species Of Thick-Thumbed Myotis From Phnom Penh, Cambodia, Acta Zoologica Academiae Scientiarum Hungaricae 68 (1), pp. 85-97 : 89-94

publication ID	https://doi.org/ 10.17109/AZH.68.1.85.2022
persistent identifier	https://treatment.plazi.org/id/606587D1-1C00-FF8B-FE11-06693CFDB972
treatment provided by	Felipe
scientific name	Myotis hayesi
status	sp. nov.

Treatment

Myotis hayesi sp. n.

( Figs 2–7 View Fig View Fig View Fig View Fig View Fig View Fig )

Holotype – HNHM 2005.82 View Materials .32. (field number # JLW 02.07), adult male, body in alcohol, skull extracted. Collected by Joe L. Walston on 5 February 2000. Measurements for the holotype (in mm) are as follows: FA = 33.8; thumb length (excluding claw) = 3.2; TAIL = 37.1; HF (excluding claws) = 6.5; longest digit of HF (excluding claw) = 2.2; greatest width of HF (at base of digits) = 3.3; TIB = 15.7; EAR= 12.6; TRAGUS = 5.3; GTL = 13.64; CCL = 12.09; CCW = 3.56; M 3 M 3 W = 5.56; ZYW = 8.41; MAW = 7.13; IOW = 3.50; BCW = 6.53; BCH

= 4.72; CP 4 L = 2.30; CM 3 L = 5.09; ML = 9.93; CM 3 L = 5.45; CPH = 2.92.

Type locality – Phnom Penh , Cambodia, 11°35’N 104°55’E. The holotype was collected in an urban area with scattered gardens planted with various species of palms and broad-leaved trees GoogleMaps .

Etymology – Named after Benjamin Hayes, in recognition of his exceptional contri- butions to improving understanding and conservation of bats in Vietnam and Cambodia. The proposed English name is ‘Hayes’ thick-thumbed myotis’.

Diagnosis – A small species of Myotis ( Table 2) with the forearm length of 33.8 mm and a skull length of 13.64 mm. The thumb, footpad, and calcar (including keel) are distinctly yellowish and contrast sharply with the overall brownish wing membranes. The thumb is shortened and thickened ( Fig. 2 View Fig ). The sole of the hind foot is wide, smooth, and concave and its greatest width (meas- ured at the base of the digits) exceeds the length of the longest digit ( Fig. 3 View Fig ). The rostrum is relatively short, and the frontal part of the skull is elevated, although the braincase is not especially globose ( Fig. 4 View Fig ). There are three upper and lower premolars, and the middle premolars are situated within the toothrow ( Fig. 5 View Fig ).

Description – This is a small species of Myotis , with a forearm length of 33.8 mm ( Table 2). The description is based on a wet specimen whose colours might have been influenced by preservation in alcohol. On the dorsal surface, individual hairs in the middorsum are 6.8–7.1 mm long and are medium brown for most of their length with a lighter tip, but without any obvious banding. The fur extends marginally onto the base of the uropatagium and hindlimbs. On the ventral surface, individual hairs are 5.8–6.0 mm long, medium-brown for approximately 60–70% of their length and then progressively lighten to pale brown in the remainder. Long hairs which are uniformly of the latter colours occur on and adjacent to the genitalia, whereas thin transverse rows of very short, off-white hairs sparsely occur over much of the uropatagium. The overall impression is of medium brown both above and below.

The nostrils are typical for the genus, as are the ears which are 12.6 mm in length and just reach the tip of the nose when laid forward. The anterior border of each ear is smoothly convex, and the tip is narrowly rounded and darker in colour than the rest of the yellowish pinna. The distal portion of the posterior margin has a small concavity, whereas the mid-portion is essentially straight. The proximal portion is broadly convex but includes a small flap of skin which renders it strongly convex prior to the base. Short transverse cartilaginous ribs occur on the inner surface of the ear conch. The tragus is narrow for most of its length (1.7 mm wide near the base), slightly less than half the height of the pinna and (HNHM 2005.82.20.) from Cambodia. Scale = 5 mm

tus (MNHG 1956.090) from Lao PDR. Scale = 5 mm

terminates in a pointed tip, which is again darker than the rest of the tragus. Its anterior margin is essentially straight, while the posterior margin is convex and has a small concavity immediately above the base. The face around the eyes is nearly naked, and the skin is light yellowish-brown.

The wings are uniformly brown in colour. The thumb is light brown above and yellowish below and possesses a fleshy pad on its ventral base ( Fig. 2 View Fig ). The hind limbs (TIB 2005.82.32.) from Cambodia

= 15.7 mm) and feet (HF = 6.5 mm) are similarly light brown above and yellowish below. Tail length is 37.1 mm. The calcar has a distinct and elongated keel and is reasonably well developed, occupying approximately half of the trailing edge of the uropatagium. The plagiopatagium is attached to the base of the first toe. The sole of the hind foot is wide, smooth, and concave, and its greatest width (3.3 mm) exceeds the length of the digits (2.2 mm excluding the claws) ( Fig. 3 View Fig ).

The penis is light yellowish and ca. 5 mm long. It slightly widens distally and is gen- erally hairless but possesses scattered, long whitish hairs around the glans.

The skull is small with a greatest skull length (GTL) of 13.64 mm and a condylocanine length (CCL) of 12.09 mm ( Table 2). In the lateral profile, the anterior portion of the skull ascends relatively steeply and subsequently very gradually, such that the highest point is attained at the rearmost portion of the braincase ( Fig. 4 View Fig ). There is no sagittal crest, but the lambdoid crests, although weak, are distinct. The rostrum is relatively short and is not inflated. The posterior border of the palatal emargination extends to the middle of the upper canine. The zygoma are moderately developed and widest posteriorly.

Upper toothrow length (CM 3 L) is 5.09 mm ( Table 2). The first upper incisor (I 2) is bicuspid, with no sign of a third, cingular cusp. Its posterior external face is in contact with the anterior internal face of the second incisor (I 3), such that I 2 is situated anterior to I 3 and clearly visible in the lateral view ( Fig. 5 View Fig ). I 2 possesses a secondary cusp which is posterior to and lower than the principal cusp. I 3 is equal in height to I 2, slightly larger in crown area ( Figs 4–5 View Fig View Fig ) and has a tiny cingular cusp on the labial side. It is separated by a brief diastema from the upper canine (C 1) which is robust and has a well-defined cingulum. The height of C 1 distinctly exceeds that of the posterior premolar (P 4), while its crown area is approximately three-quarters. Both the first and second premolars (P 2, P 3) are in the toothrow, and P 3 is visible in the lateral view and occupies half of P 2 in crown area. A faint anterolingual cusp is present on the third premolar (P 4). The first and second upper molars possess a faint paraconule and paraloph, a metaloph and a well-separated metaconule.

Lower toothrow length (CM 3 L) is 5.45 mm ( Table 2). The lower canine (C 1) has an anterior cingular cusp and a reduced posterior platform. It exceeds the last lower premolar (P 4) in height but is slightly smaller in crown area. The middle lower premolar (P 3) is small and attains no more than half the height and one-third of crown area of the first premolar (P 2). The lower molars are myotodont. The talonids of the first (M 1) and second (M 2) molars are well defined and exceed their respective trigonids in crown area. In the lateral view, the entoconids of both teeth distinctly exceed their respective hypoconids in height. The talonid of the third lower molar (M

) is reduced in comparison.

The total length of the baculum is 0.93 mm. Its basal portion is shallowly lobed and in dorsal outline is almost straight sided for the proximal half, then progressively narrows after the mid-point towards a widely rounded tip. The urethral groove is deep. In the lateral view, the distal portion of the baculum is dorsally directed only very slightly and the tip is not curved ( Fig. 6 View Fig ).