Mosia nigrescens, J. E. Gray, 1843

Bonaccorso, Frank, 2019, Emballonuridae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 350-373 : 363-364

32 . Dark Sheath-tailed Bat

Mosia nigrescens

French: Emballonure sombre / German: Dunkle reischwanzfledermaus / Spanish: Embalonuro oscuro

Other common names: Lesser Sheath-tailed Bat

Taxonomy. Mosia nigrescens J. E. Gray, 1843 ,

“ South America?” Corrected by G. E. Dobson in 1878 to “Amboina [= Ambon Island, Maluku Islands , Indonesia].”

Assignments of subspecies is based on morphological analysis of G. H. H. Tate and R. Archbold in 1939 and molecular analysis of D. J. Colgan and S. Soheili in 2008, but some affiliations are surmised based on geographical proximity. Additional molecular studies are needed to fully clarify subspecific taxonomy. Three subspecies recognized.

Subspecies and Distribution.

M. n. nigrescensJ. E. Gray, 1843 - G Moluccas, including Bum, Seram, Ambon, and possibly other islands in that island group.

M. n. papuana Thomas, 1914 - Sulawesi, N Moluccas (Morotai, Halmahera, Ternate, Bacan), Sula Is (Senana), Raja Ampat Is (Waigeo, Batanta, Salawati), New Guinea (including Supiori and Biak on Schouten Is and Umboi I) and Woodlark Is (Woodlark, Alcester), and Kai Is. Recent molecular work seems to indicate that papuana might include populations from Admiralty Is (Manus and Los Negros).

M. n. solomonisThomas, 1904-Bismarck Archipelago (New Ireland, Duke ofYork, and New Britain Is), and in N Solomons (Buka, Nissan, Bougainville, Fauro, Shortland, Vella Lavella, New Georgia, Russell, Savo, Florida, Guadalcanal, Malaita, Makira, and Uki Ni Masi Is).

Also present on Emirau I (Bismarck Archipelago), but subspecies not known.

Descriptive notes. Head-body 30-45 mm, tail 7-17-5 mm, ear 9-15 mm, hindfoot 4-7 mm, forearm 30-1-37-9 mm; weight 2-5-5-7 g. The Dark Sheath-tailed Bat is one of the smallest bats in the world. It is sexually dimorphic in body size, with females larger than males. Subspecies solomonis tends to be slightly larger on average than papuana in New Guinea. Silky dorsum is uniformly pale to medium gray-brown (raw umber); venter is somewhat paler gray-brown or bufiy brown. Ear is narrow and blundy rounded at apex. Inner surface of pinna is ribbed and sparsely haired along medial margin. Tragus is longer than broad, with blunt tip. Muzzle is short and blunt, having widely separated nostrils at anterior end. Breeding males have long phallus, nearly equal in length to tibia. Dental formula is I 2/3, C 1/1, P 2/2, M 3/3 (x2) = 34.

Habitat. Wide variety of lowland and montane primary and secondary habitats, including humid tropical broadleaf forests, mangroves, coconut groves, rural gardens, clearings, and villages from sea level to elevations of c.1600 m.

Food and Feeding. Dark Sheath-tailed Bats forage for very small insects aerially and gleaning off foliage from near ground level into canopies. Wingless ants were a major dietary component in one study of 44 stomach contents.

Breeding. Female Dark Sheath-tailed Bats likely give birth to single young twice a year. In Papua New Guinea, pregnant females are reported in February, May,June, andJuly.

Activity patterns. The Dark Sheath-tailed Bat is crepuscular and roosts under large leaves and fronds of palms, bananas, and ginger; in limestone cave entrances; and under rock overhangs and house roofs. Leaf roosts can be as low as 1 -5 m aboveground. Dark Sheath-tailed Bats emerge in late afternoon twilight to forage in well-shaded forest understories.

Movements, Home range and Social organization. When roosting in foliage, as is common, group size is regularly 2-6 individuals, with only one individual clinging to the leaf surface by its feet and thumbs and the others adpressed dorsum to venter in a stacked column. These small groups are composed of mixed sex adults and young. Four individuals roosted in such a manner under a fishtail palm ( Caryota , Arecaceae ) in Kau Wildlife Area, Madang, Papua New Guinea, and this behavior was thought to conserve heat and avoid going into torpor where forest shade temperatures are typically 10-12°C lower than body temperatures. Dark Sheath-tailed Bats are alert all day and instandy fly off if approached too closely.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Dark Sheath-tailed Bat has a large distribution and presumably large and stable overall population, and it is tolerant of habitat modification. It occurs in protected areas including Kau Wildlife Area, Madang, Papua New Guinea.

Bibliography. Bonaccorso (1998), Bonaccorso & Leary (2008b), Colgan & Soheili (2008), Dobson (1878), Flannery (1995a, 1995 b), McKean (1972), Smith & Hood (1981), Tate & Archbold (1939a), Vestjens & Hall (1977).

Figures

On following pages: 22. New Guinea Sheath-tailed Bat (Emballonura furati); 23. Beccari's Sheath-tailed Bat (Emballonura beccarti); 24. Large-eared Sheath-tailed Bat (Emballonura dianae); 25. Seri'sSheath-tailed Bat (Emballonura sertii); 26. Pacific Sheath-tailed Bat (Emballonura semicaudata); 27. Western Sheath-tailed Bat (Paremballonura tiavato); 28. Peters's Sheath-tailed Bat (Paremballonura atrata); 29. African Sheath-tailed Bat (Coleura afra); 30. Seychelles Sheath-tailed Bat (Coleura seychellensis); 31. Madagascar Sheath-tailed Bat (Coleura kibomalandy); 32. Dark Sheath-tailed Bat (Mosia nigrescens); 33. Chestnut Sac-winged Bat (Cormura brevirostris); 34. Gray Sac-winged Bat (Balantiopteryx plicata); 35. Thomas's Sac-winged Bat (Balantiopteryx io); 36. Ecuadorian Sac-winged Bat (Balantiopteryx infusca).

Subspecies and Distribution. M. n. nigrescensJ. E. Gray, 1843 - G Moluccas, including Bum, Seram, Ambon, and possibly other islands in that island group. M. n. papuana Thomas, 1914 - Sulawesi, N Moluccas (Morotai, Halmahera, Ternate, Bacan), Sula Is (Senana), Raja Ampat Is (Waigeo, Batanta, Salawati), New Guinea (including Supiori and Biak on Schouten Is and Umboi I) and Woodlark Is (Woodlark, Alcester), and Kai Is. Recent molecular work seems to indicate that papuana might include populations from Admiralty Is (Manus and Los Negros). M. n. solomonisThomas, 1904-Bismarck Archipelago (New Ireland, Duke ofYork, and New Britain Is), and in N Solomons (Buka, Nissan, Bougainville, Fauro, Shortland, Vella Lavella, New Georgia, Russell, Savo, Florida, Guadalcanal, Malaita, Makira, and Uki Ni Masi Is). Also present on Emirau I (Bismarck Archipelago), but subspecies not known.