204.

Long-nosed Luzon Forest Mouse

Apomys sacobianus

French: Apomys de la Sacobia / German: Langnasen-Philippinenwaldmaus / Spanish: Raton de bosque de Luzon de hocico largo

Other common names: Long-nosed Luzon Apomys, Pinatubo Volcano Mouse

Taxonomy. Apomys sacobianus D. H. Johnson, 1962,

“Sacobia River, Clark Air Base, Pampanga Province, Luzon, Philippine Islands.”

Apomys sacobianus, a member ofsubgenus Megapomys, may be most closely related to A. lubangensis . It co-occurs with A. zambalensis on the slopes of Mount Pinatubo, and was the more commonly captured of the two species. Published records of A. sacobianus from Isabela, Mountain, and Zambales Provinces of Luzon were disputed by G. G. Musser and M. D. Carleton in 2005, and are no longer included within this species. Monotypic.

Distribution. Recorded only from foothills and lower slopes of Mt Pinatubo, Zambales Mts, C Luzon, Philippines; it may be more widely distributed in Zambales Mts, which remain poorly surveyed for small mammals.

Descriptive notes. Head-body 135-158 mm,tail 115-159 mm, ear 21-25 mm, hindfoot 34-40 mm; weight 71-105 g. Apomys species are soft-furred, small to medium-sized murines with relatively unspecialized body form; distinguished from other Philippine murines by a distinctive suite offeatures, including long, narrow hindfeet, thinly furred tail, unreduced eyes, relatively large and thinly furred ears, vibrissae on snout very elongate and, folded back, reach to shoulder or beyond, reduction to two mammae on eachside, both inguinal, and a simplified molar pattern with cusps united into transverse laminae. Members of subgenus Megapomys are larger, shorter-tailed species active primarily on ground; in most forest habitats across Luzon Island they are the most abundant terrestrial mammal in any given community. The Long-nosed Luzon Forest Mouse, a relatively large Megapomys, has fur on upperparts brown with grayish tones, fur on underparts and inside of limbs overall grayish white (hairs gray at bases and with short white tips), the border between upperside and underside being slightly diffuse; head has whitish-gray fur on throat, cheeks, and sides of snout, and often apatch ofdarker fur on top ofsnout. Dark fur on limbs terminates at wrist and ankle, upper surfaces offoreand hindfeet being mostly white with scattered dark hairs; hindfeet relatively long but moderately broad, undersurface heavily pigmented, all plantar pads well separated, digits relatively long and bearing sharp, curved claws. Tail is relatively long (95-100% of head-body length), unusually thick, and sharply bicolored, nearly black above for entire length and pure white or

with scattered dark scales and hairs below. Cranium is similar to those of other Megapomys, but somewhat more gracile and with smaller molars than in co-occurring A. zambalensis .

Habitat. Original specimen of the Long-nosed Luzon Forest Mouse was caught in lowland secondary forest, and subsequent observations of this species in sparse, regenerating vegetation confirmed that it ishighly tolerant of disturbance. The species survived the violent eruption of Mount Pinatubo in June 1991. Recorded between ¢.100 m and at least 1080 m.

Food and Feeding. Probably omnivorous. Recent observations found that this species eagerly consumed both live earthworms and fried coconut baits.

Breeding. Five pregnant females each had two embryos, and males have testes measuring up to 13 mm x 6 mm.

Activity patterns. The Long-nosed Luzon Forest Mouse was recently reported as being active “almost exclusively at night” and very rarely climbing above ground surface (and “never more than 1 m above ground”).

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. For many years the Long-nosed Luzon Forest Mouse was known only from the holotype, which came from an area impacted by the 1991 eruption of Mount Pinatubo, butit was rediscovered in 2011-2012 and found to be abundant on the slopes of Pinatubo to at least 1080 m.

Bibliography. Balete et al. (2009), Johnson (1962), Kennerley (2016h), Heaney, Balete & Rickart (2016), Heaney, Balete, Rickart, Alviola et al. (2011), Heaney, Balete, Veluz et al. (2014), Musser (1982a), Musser & Carleton (1993, 2005).