Saint Andrew's cross toadlet  (Pelophryne signata)

Classified as Near Threatened (NT) on the IUCN Red List (1).

Measuring about the same length as a man’s thumb nail, the tiny Saint Andrew’s cross toadlet has mottled brown and orangey-red skin speckled with darker, red-tipped warts. A pale cream stripe runs along the length of the side from underneath the eye (3) and there is a pale ‘X’ shaped marking on the back (4). The fingers are blunt (truncated) (2), and its legs are a yellow-orange colour with black markings (4). Female Saint Andrew’s cross toadlets are typically slightly larger than the males (2). The call of this toad, a high-pitched sound which can be mistaken for an insect buzzing (3), can be heard at dusk and occasionally during the day (2), usually after heavy rainfall (5).

Saint Andrew’s cross toadlet is currently found in Borneo, Peninsular Malaysia and the Natuna Islands (in the South China Sea) (3), and is also thought to occur in Kalimantan, Indonesia, although it has not yet been officially recorded there (1). Those individuals found in Peninsular Malaysia and the Natuna Islands were formerly known as Pelophryne bevipes but are now classed as Pelophryne signata (3). Some species of dwarf toad in these areas look so alike that it is difficult to tell them apart, resulting in ongoing confusion concerning the species’ distribution.

Saint Andrew’s cross toadlet is found in lowland tropical, moist forests, up to 1,000 metres above sea level (1). It only inhabits areas of primary forest which restricts the area in which this species can occur to around 20,000 square kilometres (1). Within the forest, it can be found on the ground, in low vegetation up to 1.5 metres high, on tree trunks, and at tree bases (3) (6).  

The eggs of Saint Andrew’s cross toadlets are laid in small pools of rain water held in tree holes, known as phytothelms (3). Females can lay as many as 26 ivory coloured eggs, although studies of captive individuals have recorded an average of 16 eggs, laid two or three times each year (3). After hatching in this small body of water, the grey tadpoles take 30 to 40 days to develop into an adult toad (5). The exact time taken depends on the temperature of the water; in warmer water the tadpoles will develop more quickly than those in cooler water (5).

During this fascinating period of metamorphosis, Saint Andrew’s cross toadlet does not need to eat at all, as amazingly it hatches from the egg with all the energy it requires as a tadpole in its abdominal yolk sac (3). The provision by the yolk sac of all the necessary energy for growth, also known as endotrophic development, is found in very few frogs and toads (3).

Numbers of Saint Andrew’s cross toadlet are falling, principally due to the loss of primary forest (1). In Singapore, this species is found in the Bukit Timah Nature Reserve (7) which, although protected, is threatened by surrounding developments (8). The loss of forest surrounding the reserve to make way for human developments has left the reserve exposed to the wind, resulting in trees being blown down and a reduced level of moisture in the forest (8), both of which lessen the suitability of the habitat for this toad. Additionally, being situated in the densely populated country of Singapore means that Bukit Timah Nature Reserve receives high numbers of visitors each year, making this fragile habitat vulnerable to damage (8). As a result, this species now has a national status of Critically Endangered in Singapore (7)

In addition to the Bukit Timah Nature Reserve, Singapore, areas of this species’ habitat are also protected in Sarawak, Borneo (1). Continued protection of these areas may be critical in securing this species’ future.

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out about conservation efforts in Southeast Asia visit:

• WWF Singapore:
  http://www.panda.org/who_we_are/wwf_offices/singapore
• Malaysian Nature Society:
  http://www.mns.my/