206.

Zambales Forest Mouse

Apomys zambalensis

French: Apomys des Zambales / German: Zambales-Philippinenwaldmaus / Spanish: Raton de bosque de Zambales

Other common names: Zambales Apomys

Taxonomy. Apomys zambalensis Heaney et al., 2011,

“Philippines: Luzon I[slan]d.: Bataan Province: 0-1 km N Mt. Natib peak, 1150 m, 14-71513°N,120-39892°E.”

Newly collected in 2005, A. zambalensis is a member of subgenus Megapomys and its nearest phylogenetic relatives may be A. wridensis, A. aurorae, and A. magnus . It is sympatric in the Zambales Mountains with A. sacobianus, but is found only at lower elevations than A. brownorum on Mount Tapulao. Monotypic.

Distribution. Restricted to the Zambales Mts of W Luzon, Philippines.

Descriptive notes. Head-body 127-163 mm,tail 123-158 mm, ear 20-23 mm, hindfoot 35-40 mm; weight 67-112 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 each side, 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 they are the most abundant terrestrial mammal in any given community. The Zambales Forest Mouse is the second largest species of Megapomys and has fur on upperparts soft but relatively short and bright rusty orange, fur on underparts and inside of limbs pale to medium gray at bases and white with slight to heavy ocherous wash at tips; border between upperside and underside is slightly diffuse; head with whitish-gray fur on throat but cheek and sides of snout orange brown; ears are relatively large, thinly furred, and less heavily pigmented than those of other Megapomys. Dark fur on forelimb terminates well above wrist, followed by a band of pale orange fur and then bywhite fur on wrist and forefoot; dark fur on hindlimb terminates at ankle, hindfeet mostly white, sometimes with scattered dark hairs; hindfeet are relatively long and broad, undersurface pigmented over most of length including some plantar pads, hallucal pad relatively short and placed well forward, other plantar pads relatively large but well separated; hallux long, reaching almost to top of adjacent interdigital pad, other digits also relatively long and narrow,all digits bearing sharp, curved claws. Tail is relatively long (94-100% of head-body length) and sharply bicolored, dark brown above and white below for all or most of length. Cranium is similar to those of other Megapomys but rostrum relatively long and robust, braincase somewhat elongate and flattened. Chromosomal complement has 2n = 44, FN> 58, autosomes include two pairs of large submetacentric, two pairs of medium-sized metacentric or submetacentric, and 15 pairs of small to large telocentric or subtelocentric chromosomes. The X chromosome is a medium-sized submetacentric and the Y chromosome a small telocentric.

Habitat. Evergreen tropical rainforest, including lowland and montane rainforest types, and narrowly extending into mossy forest, at elevations of 365-1690 m. The Zambales Forest Mouse occurs in lightly to heavily disturbed forest, as well as in primary forest, and on Mount Pinatubo was abundant—though less so than the Longnosed Luzon Forest Mouse ( A. sacobianus)—in sparse regrowth vegetation after the violent eruption of 1991. It was the most commonly captured small ground mammal on Mount Tapulao from 925 m to 1690 m and on Mount Natib from 900 m to 1250 m.

Food and Feeding. Zambales Forest Mice are reported as avidly consuming live earthworm bait and fried coconut and are “best considered to be omnivorous.”

Breeding. A pregnant female carried two embryos.

Activity patterns. The Zambales Forest Mouse is active almost exclusively at night and rarely, if ever, climbs above ground surface (and never more than 1 m above ground).

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The IUCN Red List butits relatively wide distribution and elevational range, local abundance, and occurrence in regrowth habitat following heavy disturbance suggest a high degree ofresilience.

Bibliography. Balete et al. (2009), Engelbrektsson & Kennerley (2017), Johnson (1962), Heaney, Balete & Rickart (2016), Heaney, Balete, Rickart, Alviola et al. (2011), Heaney, Balete, Veluz et al. (2014), Musser (1982a), Musser & Carleton (1993, 2005).