221.

Sierra Madre Shrew Mouse

Soricomys musseri

French: Rat de Musser / German: Musser-Spitzkopfmaus / Spanish: Raton musarana de Sierra Madre

Other common names: Palanan Shrew Mouse

Taxonomy. Archboldomys musser i Rickart et al., 1998,

Mount Cetaceo, Cagayan Province, Luzon Island, Philippines.

Genus Soricomys was recently erected during arevision of genus Archboldomys following molecular and morphological findings, and taxon musseri was then transferred from latter genus to Soricomys . Genetically, S. musseri is sister to a clade including S. kalinga + S. montanus . Monotypic.

Distribution. Known only from type locality and Mt Anacuao, NE Luzon I, Philippines.

Descriptive notes. Head-body 91-105 mm, tail 89-93 mm, ear 14 mm, hindfoot 18— 23 mm; weight 30-32 g. The Sierra Madre Shrew Mouse with a slender snout and small eyes. Dorsal pelage is a dark reddish brown, which is paler than in the Leonardo Shrew Mouse ( S. leonardocoi). Ventral pelage is shorter and a slightly paler reddish brown. Feet are reddish brown dorsally, and darker on plantar and palmar surfaces. Claws are long and opaque and they have a nailed pollex. Ears are small, rounded, and the same color as the dorsal pelage. Tail is relatively short (89-98% of head-body length) and dark, being a similar color to the dorsal pelage. Skull has a long nasal, dorsally inflated and high cranium, short and broad tympanic hook, narrow squamoso-mastoid vacuity, spacious postglenoid vacuity, slender, backswept coronoid process, and narrow, broadly angled angular process relative to condyle compared to its congeners. They have a longer tail, are generally larger, have a flatter cranium and shorter and paler pelage compared to the Leonardo Shrew Mouse, which it is most similar too. Females bear two pairs of inguinal mammae. Karyotype is 2n = 44.

Habitat. Mossy forest between 1450 m and 1760 m, but probably also found at higher altitudes.

Food and Feeding. The Sierra Madre Shrew Mouse forages in litter of forest floor, searching for insects, earthworms, and other invertebrates.

Breeding. Two young adult females were captured in June, while scrotal males were reported in May and June.

Activity patterns. The Sierra Madre Shrew Mouse is diurnal and terrestrial.

Movements, Home range and Social organization. Densities appear to be fairly low at all known localities.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Sierra Madre Shrew Mouse is known from only seven specimens; the holotype and six specimens collected in 2005. Further surveying in other areas with suitable habitat is needed, as the species may have a wider distribution then currently known. Their known distribution is located in the Penablanca Protected Landscape and there are no major threats to the species since its habitat is very secluded and inaccessible.

Bibliography. Balete, Alviola & Duya (2017), Balete, Rickart et al. (2012), Danielsen et al. (1994), Heaney, Balete & Rickart (2016), Rickart & Heaney (2002), Rickart et al. (1998).