194.

Large Mindoro Forest Mouse

Apomys gracilirostris

French: Apomys de Mindoro / German: Schmalschnauzen-Philippinenwaldmaus / Spanish: Raton de bosque de Mindoro

Other common names: Large Mindoro Apomys

Taxonomy. Apomys gracilirostris Ruedas, 1995,

“Philippines: Mindoro Island; Mindoro Occidental Province; Municipality of San Teodoro, North Ridge approach to Mount Halcon, ca. 1580 m; ca. 13°16’48’N, 121 °B9°19°E.” Although currently placed in subgenus Megapomys, Apomys gracilirostris is morphologically divergent and appears to be the earliest derivative of this lineage. Monotypic.

Distribution. Currently recorded only on N ridge of Mt Halcon, Mindoro I, Philippines; likely widespread in mountains of Mindoro, an area that remains poorly surveyed for small mammals.

Descriptive notes. Head-body 137-147, tail 135-185 mm, ear 14-22 mm, hindfoot 33-45 mm; weight 71-140 g. Species of Apomys are soft-furred, small to medium-sized 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 simplified molar pattern with cusps united into

transverse laminae. Members of subgenus Megapomys are larger, shorter-tailed species active primarily on ground. The Large Mindoro Forest Mouseis one of the bigger and more unusual species of Megapomys. Fur on upperparts is dark brown with fine black flecking, the latter produced by numerous short black guard hairs, body hairs with light gray bases; fur on underparts and inside of all limbs usually similar in tones to back but paler, some individuals with silvery tipping; colors of upper and lower parts blend without sharply defined boundary; ears darkly pigmented on interior surface, somewhat paler externally. Dark fur of limbs extends onto upper surfaces of foreand hindfeet, digits pigmented and with short dark hairs; hindfeet relatively short and broad compared with those of other Megapomys, undersurface with dark gray pigment apart from on pads, digits relatively short and stocky, plantar pads moderately large but well separated, first digit very long, reaching to front of first interdigital pad. Tail is relatively long (on average 105% of head-body length), dark above and only slightly paler below for entire length, some individuals with short white tip (2-10 mm), scales in 14 rows per cm near base and at middle oftail. Cranium is larger but quite gracile compared with most Megapomys, with long, slender rostrum, relatively small molars, and very narrow incisors (lowers described as lacking enamel).

Habitat. The Large Mindoro Forest Mouse was abundant in 1992 in evergreen tropical montane rainforest on Mount Halcon. At elevations between 1250 m and ¢.1600 m the forest canopy was floristically diverse, with heavy growth of moss, and understory generally dense, with areas oftree ferns, climbing bamboos and palms including pandans ( Pandanus, Pandanaceae). Above 1600 m, the canopy consisted entirely of the pine Agathis philippinensis, with dense understory of bamboos, pandans and gingers. Recorded at elevations of 1250-1950 m.

Food and Feeding. I.. A. Ruedas speculated that it might feed on insects on account of its gracile dentition.

Breeding. Ruedas reported in 1995 that “one female had three embryos;” largest scrotal testes measured 7 mm x 4 mm.

Activity patterns. Ruedas offered reasonable speculation that this species was scansorial on basis of the form ofits feet and relative length oftail. Apparent absence of any member of subgenus Apomys on Mindoro may allow the Large Mindoro Forest Mouse a greater ecological breadth thanother members of the Megapomys lineage.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Montane habitats on Mindoro Island are currentlystable, but the island has been subject to past episodes of deforestation. The status of this species has not been assessed in the field since its initial discovery.

Bibliography. Heaney, Balete, Dolar et al. (1998), Heaney, Balete & Rickart (2016), Heaney, Balete, Rickart, Alviola et al. (2011), Justiniano et al. (2015), Kennerley (2016f), Musser & Carleton (2005), Ruedas (1995).