783.

Sommer’s Sulawesi Rat

Sommeromys macrorhinos

French: Rat de Sommer / German: Sommer-Sulawesi-Langnasenratte / Spanish: Rata de Célebes de Sommer

Other common names: Sommer'’s Rat

Taxonomy. Sommeromys macrorhinos Musser & Durden, 2002,

“2400 m near the summit

of Gunung Tokala (02°13’S/120°04°E), a

mountain between the Rampi and Seko

valleys in the southern section of central Sulawesi (Province Sulawesi Tengah),” Indonesia.

Sommeromys is sister to a cladeincluding Waiomys and Gracilimus. This Sommeromys + Waiomys + Gracilimus clade is sister to the Paucidentomys + Echiothrix and Tateomys + Melasmothrix clade. Monotypic.

Distribution. Known only from a few localities C Sulawesi (Mt Tokala and Mt Gandangdewata).

Descriptive notes. Head-body 295-108 mm, tail 173-193 mm, ear 16-20 mm, hindfoot 29-31 mm; weight 24-30 g. Sommer’s Sulawesi Rat is small, gracile, and very distinctive species of endemic Sulawesi rat. Pelage is long, thick, and very soft. Dorsum is dark brownish gray, individual overhairs being gray for three-quarters oftheir lengths, with dark buffy brown tips, and guard hairs inconspicuous and unpigmented at tips. Ankle region is sparsely covered in fine, short brown hair. Venteris grayish white and soft, with overhairs that are shorter with white tips. Dorsum and venter are not sharply demarcated. Ears are oval, large (compared with body size), rubbery, unpigmented (except for a few pale gray spots on distal curvature), and nearly naked; vibrissae are long and fine. Tail is ¢.188% of head-body length, whip-like, inconspicuously haired, dark brown dorsally and on sides, unpigmented ventrally, and naked and lacking scales on distal 30 mm of dorsal part, which might indicate it is prehensile. There are four digits on forefeet and five on hindfeet, with small, sickle shaped claws; fifth digits of hindfeet are extremely reduced and have flattened nail instead of claw. Skull is small and delicate, with globular braincase and long narrow rostrum. The sucking louse Hoplopleura sommeri has been recorded on Sommer’s Sulawesi Rat.

Habitat. Montane tropical rainforests and transitional habitats from highlands to lowlands at elevations of 1600-2600 m. Sommer’s Sulawesi Rat has been captured in slightly disturbed habitat.

Food and Feeding. Sommer’s Sulawesi Rat is insectivorous. Stomach contents of some specimens had nematodes, muscoid fly eggs, and various insect fragments; one specimen had some vascular plant material in its stomach.

Breeding. No information.

Activity patterns. Sommer’s Sulawesi Rat is nocturnal and probably terrestrial, scansorial, and arboreal.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. Sommer’s Sulawesi Rat was only recently described and has not been caught very often. It is probably threatened by deforestation and cultivation.

Bibliography. Achmadi et al. (2014), Musser & Carleton (2005), Musser & Durden (2002), Musser, Lunde & Ruedas (2008b), Rowe et al. (2016a).