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Apomys brownorum

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Apomys brownorum

Heaney, et al. 2011. Fieldiana Life and Earth Sciences, 2: 25. Type Locality: Barangay Salasa, Mt. Tapulao, Palauig Municipality, Zambales Province, Luzon Island, Philippines, elevation 2024 m (15d 28’54.8”N, 120d 07’10.4”E)  

© The Field Museum. Photograph by L Heaney and A Niedzielski.

 

Order: RODENTIA

Family: Muridae

English common names: Mt. Tapulao apomys, Browns’ apomys, Mt. Tapulao forest mouse

 

Identification:

Total length: 230-255 mm; tail: 107-116 mm; hind foot: 31-35 mm; ear: 21 - 22 mm; weight: 60-84 g. Apomys brownorum is the smallest species of Megapomys. The tail is proportionately short (82-90% of head and body length) and distinctly bicolored—dark grayish-brown dorsally and nearly white ventrally. Apomys brownorum has especially soft, dense, moderately long, rich dark brown fur dorsally.  The ventral fur is dark gray at the base, with grayish-ochraceous tips.  Dark fur extends onto the posterior one-third of the forepaws and four-fifths of the hind foot.  

Compared to A. zambalensis, which occurs lower on Mt. Tapulao, Apomys brownorum is much darker dorsally and ventrally; A. zambalensis has rich orange-brown fur dorsally and pale, slightly ochraceous fur ventrally.  Apomys brownorum is smaller than A. zambalensis in virtually all measurements.  Apomys brownorum and A. banahao are closely related and very similar species in appearance. The dorsal fur of A. brownorum is slightly paler and shorter; the ventral fur of A. brownorum is washed with pale ochraceous, while that of A. banahao is washed with ashy gray. The tail of A. brownorum is usually shorter both absolutely and relative to head and body length than that of A. banahao.  Apomys microdon and A. musculus, which occur syntopically, are both much smaller and have proportionately longer tails.

 

Distribution:

Known only from a single locality near the peak of Mt. Tapulao, Zambales Province, Luzon Island.  They should be sought near the tops of the other high peaks in the Zambales Mountains (FMNH, PNM; Heaney et al., 2011). 

© The Field Museum

 

Habitat and Ecology:

Currently documented from mossy forest at 2024 m, where they are abundant in old-growth forest and regenerating secondary forest. They are active at night, feeding on the forest floor on earthworms and other invertebrates and on seeds.  They may overlap with Apomys zambalensis at the transition between montane and mossy forest, which occurs at about 1800 m on Mt. Tapulao (Balete et al., 2009; Heaney et al., 2011).  Further studies are needed.

© The Field Museum. Illustration by V Simeonovski.

 

Status:

Abundant at the one locality where they have been studied, in both old-growth mossy forest and regenerating secondary forest, but the habitat is now being subjected to intensive chromium mining, with an unknown impact on this endemic species.  Further study of their status is needed.

 

Comments

No data were collected on Mt. Tapulao between 1690 and 2024 m, so we infer the lower elevation limit for this species to fall somewhere within that range.