Shrub frog  (Philautus acutirostris)

Philautus acutirostris is classified as Vulnerable (VU) on the IUCN Red List (1).

Named due to its frequent presence on the branches and leaves of bushes and small trees, this shrub frog (Philautus acutirostris) is characterised by its pointed snout, partially webbed feet and rough or granular belly (4), a feature of many arboreal frogs thought to help increase water absorption (5).

The tiny body of Philautus acutirostris is brown, green and grey, and can display a wide variety of patterns (6). Typically though, it is a brownish colour (2), marked with small pale dots on the sides and limbs (3) (6). In contrast, the underside is a creamy ivory colour with variable brown blotches (6).

Philautus acutirostris is endemic to the Philippines and is found on the islands of Basilan, Jolo and the easternmost island Mindanao (1).

On Mindanao, its natural distribution encompasses Dapitan peak on the Zamboanga Peninsula and Mount Hilonghilong (2).

Philautus acutirostris is a rainforest inhabitant and, although occasionally terrestrial, it usually adopts an arboreal lifestyle (1). It is found from elevations of approximately 400 metres in dipterocarp forest to more than 2,000 metres in montane forest (2). At times it can be found quite far from any body of free water (7).

Although the genus Philautus was discovered in 1822, knowledge of these frogs is still fairly limited due to their small size and great variety of colours (4). Male Philautus frogs typically have internal vocal sacs (6) and the euphonious tinkling sound, which is characteristic of these tiny green and brown frogs, is most often heard during the rainy season (7).

Philautus acutirostris has a very unique method of reproduction, as it exhibits direct development. That is, the eggs develop straight into froglets, typically having no aquatic tadpole stage (4). Following copulation, the female shrub frog produces a clutch of 10 to 20 eggs (2). The eggs are usually laid on the ground, under stones or dead leaves, or on the leaves of a fern, small shrub, or tree (4). Such plants are thought to typically include the wild banana plant and epiphytic ferns (2).

The major threat to Philautus acutirostris is the continued loss of lower montane forest and lowland rainforest habitat due to expanding agricultural plantations, mining activities, quarrying, logging, and human settlements (1).

Some populations of Philautus acutirostris occur within protected National Parks. However, there is currently a need to improve the protection of additional habitats, particularly on the island of Mindanao, to prevent further population declines (1).

Find out more about the shrub frog and its conservation:

• Amphibia Web:
  http://www.amphibiaweb.org/
• IUCN/SSC Amphibian Specialist Group:
  http://www.amphibians.org/ASG/Home.html
• HERPWATCH Philippines:
  http://www.herpwatch.org/