197.

Mount Irid Forest Mouse

Apomys iridensis

French: Apomysde I'lrid / German: Mount-Irid-Philippinenwaldmaus / Spanish: Raton de bosque de Irid

Other common names: Irid Apomys, Southern Sierre Madre Forest Mouse

Taxonomy. Apomys iridensis Heaney et al., 2014,

“Philippine Islands: Luzon Island, Rizal Province, Rodriguez Municipality: 1:25 km S, 0-5 km W Mt. Irid peak, 14-78000°N, 121-321623°E, elev. 920 m.”

Apomys iridensis, newly collected in 2009, is a member of subgenus Megapomys, and may be most closely related to A. zambalensis and A. auwrorae. Range is not known to overlap with that of any other species of Megapomys, but on Mount Irid A. iridensis is sympatric with A. microdon (of subgenus Apomys). Monotypic.

Distribution. Currently recorded only from Mt Irid, E Luzon I, Philippines, but it is potentially widespread on other, unsurveyed peaks in S Sierra Madre.

Descriptive notes. Head-body 136-155 mm, tail 132-157 mm, ear 19-21 mm, hindfoot 35-40 mm; weight 76-104 g. Species of Apomys are soft-furred, small to mediumsized murines with relatively unspecialized body form; distinguished from other Philippine murines by a distinctive suite of features, 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 active on ground; in most forest habitats across Luzon Island, they are the most abundant terrestrial mammal in any local community. The Mount Irid Forest Mouse, one of the largest Megapomys, has fur on upperparts, flanks and outer surfaces of limbs dense and very soft, dark brown with deep reddish tones; fur on underparts and inside of limbs gray at bases with short white tips, sometimes with pale orange wash; boundary between colors of upperside and underside abrupt; ears relatively large, darkly pigmented. Dark fur of limbs does not extend onto upper surfaces of foreand hindfeet, which are nearly white, unpigmented, and with mainly white and a few, scattered dark hairs; hindfeet relatively elongate, undersurface with dark pigmentation. Tail is relatively long (approximately equal to head-body length), sharply bicolored, dark above and white below for entire length. Cranium has moderately broad, robust rostrum,and relatively broad molars compared with congeners.

Habitat. Evergreen tropical rainforest habitats, including regenerating lowland rainforest and primary montane rainforest, at 700-1320 m. It may extend to lower elevations.

Food and Feeding. [.. R. Heaney and coworkers reported in 2016 that Mount Irid Forest Mice “showed a weak preference for live earthworm bait rather than fried coconut but are probably best considered to be omnivorous.” Breeding. Heaney and coworkers reported that “three pregnant females each carried one embryo, and one has two embryos.” Activity patterns. Nearly all captures were made at night, and all except one were captured on ground surface.

Movements, Home range and Social organization. Mount Irid Forest Mice are abundant on Mount Irid, but there is no other specific information on this population.

Status and Conservation. Not assessed on The IUCN Red List. The long-term prospects of this species may rest on whether it occurs more widely at higher elevation in the Southern Sierre Madre, above the potential range of forestry activities.

Bibliography. Balete, Heaney & Rickart (2013), Heaney, Balete & Rickart (2016), Heaney, Balete, Rickart, Alviola et al. (2011), Heaney, Balete, Veluz et al. (2014), Justiniano et al. (2015).