450.

Frosted Myotis

Myotis pruinosus

French: Murin givré / German: Honshu-Bartfledermaus / Spanish: Ratonero de Japén

Other common names: Blackish \ Whiskered Bat

Taxonomy. Myotis pruinosus Yoshiyuki, 1971,

Geto Hot Spring, Waga-Machi, Waga-Gun, Iwate prefecture, north-eastern Honshu, Japan.

Subgenus Myotis; montivagus species group. See M. annectans . Most recent phylogenetic studies show that M. pruinosus as sister to M. yanbarensis and M. secundus and more distantly related to montivagus species group. Ancestral M. pruinosus and M. yanbarensis might have adapted to warm temperatures, with probable origin in South-east Asia. Monotypic.

Distribution. Endemic to Japan, recorded from Honshu, Shikoku, and Kyushu Is.

Descriptive notes. Head-body 37-44 mm,tail 33-40 mm, ear 10-3-13- 3 mm, hindfoot 7-5—8- 6 mm, forearm 30-34 mm; weight 4-7 g. Fur dense, velvety, and short (c.5- 5 mm in length on middle of back). Dorsum is dark grayish brown, conspicuously frosted with ashy or whitish tips. Venteris slightly lighter than dorsum,frosted with buffy hair tips in adults and whitish in young. Ears are narrow and short; tragusis relatively short (5- 5-7 mm). Hindfeet with claws are large (c.64% oftibia); lower leg is slender. Plaglopatagium is attached at base offirst toe. Tail and calcar are long, and calcar lacks keel. Skull has broad zygomatic breadth (zygomatic width ¢.65% of condylo-basal length) and narrow interorbital constriction (width ¢.50% of braincase). In dorsal view, braincase is laterally swollen; sagittal and temporal crests are poorly developed; and lambdoid crestis laterally strong. Dorsal profile from anterior nasal part to posterior nasal region is almoststraight and then rises abruptly to frontal region. I? and I? have secondary cusps and are subequal in height and crown area, distance between I* and canine narrower than transverse diameter of I’; P? and P*® are similar in shape, the latter c.33% the former in crown area and height and positioned in tooth row. Upper molars have distinct protoconules. There are three pairs of lower incisors; I, is larger than I, and I, forming V-shaped row between canines. P, and P, are subequal in size and in tooth row. Condylo-basal lengths are 12-12- 8 mm; maxillary tooth row lengths are 4-9-5- 3 mm. Chromosomal complement has 2n = 44 and FN = 52. The Frosted Myotis has pericentric inversion on chromosome 1. Y-chromosome is submetacentric, and X-chromosomeis subtelocentric.

Habitat. Intact mature primary mountain forests down to elevations of 200-300 m. The Frosted Myotis was assumed to be more widely distributed in warm temperature evergreen lowland broadleaf forests on south-western Japanese plains, but it is presently absent due to lack of large trees containing crevices and cavities and survives only in low-elevation mountains that contain nearly mature forests with tree holes for roosting.

Food and Feeding. No information.

Breeding. Parturition occurs in mid-July. Litter size is one young.

Activity patterns. The Frosted Myotis has been observed flying along forest edges, trails, and streams and above grasslands at night. There are no records from caves except for one hibernating individual from Shikoku, which was found in a crack in the ceiling. Tree hollows are primary diurnal refuges. Echolocation call is FM type, with average end frequency of 38-7 kHz (33—41-8 kHz), peak frequency of 52-4 kHz (49-7-54-7 kHz), and duration of 2:8 milliseconds (2-6-3 milliseconds).

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Endangered on The IUCN Red List. Extent of occurrence of the Frosted Myotisis less than 5000 km?, whichis severely fragmented and faces ongoing decline of mature forests. Deforestation of old-growth evergreen forests for agriculture, conifer plantations, logging, and infrastructure development for expanding human settlements is a major threat. It occurs in some protected areas.

Bibliography. Abe et al. (2005), Amadoretal. (2018), Corbet (1978), Funakoshi (2010), Harada & Uchida (1982), Horacek et al. (2000), Kawai et al. (2003), Koopman (1994), Maeda (2008f), Ohdachi et al. (2009), Ruedi, Csorba et al. (2015), Ruedi, Stadelmann etal. (2013), Simmons (2005), Tsytsulina (2004), Volleth & Heller (2012), Yoshiyuki (1971, 1989), Zhang Zhenzhen et al. (2009).