Myotis kalkoae Tiunov, Jiang & Liu, 2025

Tiunov, Mikhail Petrovich, Liu, Sen, Feng, Jiang, Soisook, Pipat & Jiang, Tinglei, 2025, A new species of Myotis from China with notes on the siligorensis species group (Chiroptera, Vespertilionidae), ZooKeys 1258, pp. 333-356 : 333-356

Myotis kalkoae Tiunov, Jiang & Liu sp. nov.

Figs 5 A , 6 A , 7

Type material.

Holotype. • IBSS CQ-08 c-16 , adult male, body in 75 % alcohol, skull and baculum extracted, collected by Liu Sen in July 2008 from Shenxian Cave , near Jiangkou village, Wulong Town, Chongqing Province, China ( 29°16'451"N, 107°50'495"E) . Paratypes. • IBSS HUN-08 c-24 , adult male, body in alcohol, skull extracted, collected by Sen Liu in July 2008 from Tangle Cave , near Zhaiyang village, Jishou Town, Hunan Province, China ( 28°17'927"N, 109°39'364"E) ; • NNU GZ-07-74 , adult male, body in alcohol, skull extracted, collected by Sen Liu in July 2008 from Shizilu Cave at Dongnuang Village ( 28°18'539"N, 106°12'367"E) .

Diagnosis.

A Myotis species of small size was established as belonging to the siligorensis species group, with the following characteristics: forearm length = 34.9, 35.3 mm ( n = 2), condylobasal length of skull = 11.9, 12.1 mm ( n = 2). The margin of the plagiopatagium was attached to the metatarsus of the first toe. The foot, including the claw, accounted for 50 % (49, 51 %, n = 2) of the tibia. The frontal portion of the skull was distinctly elevated above the low rostrum, as in M. siligorensis , M. badius , M. csorbai , and M. annamiticus . Both small upper premolars (P 2 and P 3) were present in the tooth row and clearly visible from a lateral view. The lower molars were of the seminyctalodon type, as in M. siligorensis , M. badius , M. phanluongi , and M. annamiticus . This new form could be clearly distinguished from all the latter species by the shape of the baculum. The measurements of the holotype (in mm) were as follows: body length – 35, tail length – 28, length of the free tail tip – 0.5, ear length – 11.9, tragus length – 5.5, tibia length – 12.4, foot length with claws – 7.3, forearm length – 34.9, length of the first digit (without claws / with claws) – 3.6 / 5.0, Mc 2 – 28.2, Mc 3 – 29.8, Ph 3.1 – 9.3, Ph 3.2 – 8.2, Ph 3.3 – 6.4, Mc 4 – 29.1, Ph 4.1 – 9.4, Ph 4.2 – 8.3, Mc 5 – 29.1, Ph 5.1 – 8.4, Ph 5.2 – 7.8; CBL – 11.9, CCL – 11.1, W – 6.8, BCW – 6.4, BCH – 5.6, IOW – 3.2, ZW – 8.0, WR – 4.1, LR – 2.95, CM 3 – 4.5, PD – 0.5, P 4 M 3 – 3.45, WM 3 – 1.25, LM 3 – 0.6, CC – 3.3, M 3 M 3 – 5.2, LMD – 9.3, HMD – 2.5, MCM 3 – 4.9.

Description.

The hairs of the dorsal pelage were brown with a grayish tinge. The fur was uniformly paler on the ventral surface. Each ear was comparatively short, not extending, when laid forward, to the tip of the nose. The tragus was relatively short, a little less than 1 / 2 as high as the conch. The tragus’s anterior border was straight with a rounded tip, and its widest portion was in the lower 2 / 3. The lobe at the base of the tragus was thin, wavy, curved, and perpendicular to the tragus. The outer angle exhibited a mastoid form and points upward (Fig. 5 A ). The wing membrane was broad, and the fifth finger was relatively long, ~ 84 % of the third finger in length. The calcar was ~ 35 % (32.2, 43.0 %, n = 2) the length of the posterior border of the interfemoral membrane when measured from the foot to the tip of the tail; it was without a keel or terminal lobe. The tail was relatively long, at 82 % of the head and body length; ~ 0.45 mm of its tip was free from the membrane. The ventral surface of the interfemoral membrane was sparsely haired, and the hairs were ~ 0.7–0.8 mm in length.

The frontal portion of the skull was distinctly elevated above the low rostrum, as in M. csorbai , M. badius , and M. siligorensis . The height of the brain sample was ca. 78.9 % (75.4, 82.35 %, n = 2) of the skull width. The upper surface of the rostrum contained a visible groove in the middle (Fig. 6 A ). The interorbital constriction was remarkably narrow; the interorbital width was ~ 46 % of the skull width. The posterior border of the naris extends to the posterior margin of the upper canine. The sagittal crest was scarcely evident, and the lambdoid crests were visible laterally but were lacking in the central portion. The outer upper incisor (I 3) possessed three or four cusps and was equal to or slightly greater than the internal incisor (I 2). The upper canine was short; it scarcely exceeded the posterior premolar (P 4) in height and occupied a smaller crown area. The anterior premolar (P 2) was in contact with the canine and <1 / 2 of its height. The middle premolar (P 3) was small, <2 / 3 of P 2 in height and ~ 1 / 2 the crown area. Both small upper premolars were situated in the toothrow and were visible when the skull was viewed laterally. The posterior premolar (P 4) was low, with an antero-internal cusp. The upper molars possessed well-developed protoconules. In the lower dentition, the first (I 1) and second lower incisors (I 2) were three- or four-lobed. The canine was small, and its height was less than that of the posterior lower premolar (P 4). The first lower premolar (P 2) was ~ 2 / 3 the height of the canine. The second lower premolar (P 3) was ~ 1 / 2 the height of P 2 and was located within the toothrow. The lower first molar was of the nyctalodont type (the postcristid was connected to the hypoconulid). The second molar was of a seminyctalodont dental type (the postcristid connects to both the entoconid and the hypoconulid). The third molar was a typical myotodont.

Baculum. The baculum of M. kalkoae sp. nov. was essentially similar to that of the other species within this group. The feature was a small bonelet that was broadly rounded proximally and narrowed distally. Viewed laterally, it was recurved in shape (Fig. 7 ). A reduced urethral groove was present proximally on the ventral surface; it appeared as a triangularly shaped, poorly articulated depression. The length was ~ 0.5 mm; the greatest width was ~ 0.15 mm ( n = 2 adults).

Etymology.

The new species is named in honor of Dr. Elisabeth Kalko (1962–2011), head of the Institute of Experimental Ecology (University of Ulm, Germany), who, in the early 2000 s, was one of the most prominent experts in the field of bat community ecology.

Figures

Figure 5. Shape of the tragus and lobe at the base of the tragus: A. Myotis kalkoae sp. nov. (tragus, lobe at the base of the tragus (anterior view, view from above and lateral view )); B. Myotis sowerbyi (tragus, lobe at the base of the tragus (anterior view, view from above and lateral view )); C. Myotis badius (tragus, lobe at the base of the tragus (anterior view, view from above and lateral view )); D. Myotis siligorensis (tragus, lobe at the base of the tragus (anterior view, view from above, and lateral view )); E. Myotis alticraniatus (tragus, lobe at the base of the tragus (anterior view, view from above, and lateral view )); F. M. phanluongi (tragus, lobe at the base of the tragus (anterior view, view from above, and lateral view )).

Figure 6. A. Dorsal, ventral, and lateral views of the cranium and mandible of Myotis kalkoae sp. nov. (holotype); B. Dorsal, ventral, and lateral views of the cranium and mandible of Myotis sowerbyi; C. Dorsal, ventral, and lateral views of the cranium and mandible of M. alticraniatus.

Figure 7. Baculum of Myotis kalkoae sp. nov., dorsal, ventral, and lateral views. Scale bar: 0.2 mm.