Flat-shelled spider tortoise  (Pyxis planicauda)

Classified as Critically Endangered (CR) on the IUCN Red List (1), and listed on Appendix I of CITES (3).

The various English common names for this small tortoise generally refer to the noticeably flattened nature of either its oblong upper shell (carapace) or its tail (2) (4). The carapace is distinctively patterned, with each scute having a light brown to yellow centre surrounded by a wide, dark brown to black border. In older tortoises, an additional yellow border may surround this dark border (4). Yellow rays extend outward from the centre of the scutes, across the dark border. The scutes around the perimeter of the shell (marginals) are dark with a yellow band (2) (4). The lower shell (plastron) is yellow with scattered dark spots or rays along the sides (2) (4). The limbs range from yellow to brown in colour, and large yellow scales cover the hind legs (2). By contrast, the head ranges from dark brown to black, with some variable yellow markings (2) (4).

Endemic to the west coast of Madagascar (5), between the Monrondava and Tsiribihina Rivers (4).

Confined to lowland fragments of dry, deciduous forest, found only on the west coast of Madagascar (5).

The flat-shelled spider tortoise is active only during the hot/rainy season (4) (5), from December until around March (6), and is most active during and after rains (4) (5). During the cooler dry season, this species buries itself and lies dormant in the leaf litter of the forest floor (a period known as aestivation) (4). Breeding occurs during the hot/rainy season, and is followed a month later by egg-laying (5). Females may produce up to three clutches a year (5), each containing only one, relatively large egg (4). Hatching is timed with the return of the rainy season the following December (5).

The diet of the flat-shelled spider tortoise consists of fallen fruits from trees, and the shoots and leaves of bushes (4).

Like Madagascar’s other tortoises, the flat-shelled spider tortoise has been severely threatened by rampant degradation of its habitat and harvesting for the international pet trade (2). Deforestation has been widespread largely due to conversion to agriculture and timber extraction (2) (5) (6). The species’ already precarious position has been compounded by excessive harvesting to sell to private collectors, which has resulted in its total elimination from some forest fragments. This species has also been sold in Chinese marketplaces for food. Even since their listing on Appendix I of the Convention on International Trade in Endangered Species (CITES), with export of wild specimens therefore banned, there have still been reports of tortoises being smuggled out illegally. In addition, there are serious concerns that specimens advertised as ‘captive-bred’ are really captured from the wild. Given that the species has a low reproductive rate, and it is mostly breeding females that are collected, the flat-shelled spider tortoise has little capacity to recover from sustained over-harvesting. Floods caused by cyclones are one of the natural threats which this species has to endure (2).

The majority of the flat-shelled tortoise’s range now occurs within the recently designated Menabe Antimena protected area, which offers some hope that a significant proportion of its remaining habitat will be preserved (6). Other protected areas of forest occur within this species’ range, such as the special Andranomena Forest Reserve and private Analabe Reserve, but regulations are believed to have been rarely enforced and the precise status of the species in these areas is currently unknown (2).

The flat-shelled spider tortoise has proven difficult to breed in captivity (2). Thus, creating an effective and sustainable captive-breeding programme to supply demand or to fuel reintroduction efforts would appear difficult. The flat-shelled spider tortoise was raised from Appendix II to Appendix I of CITES in 2003, banning all international trade in wild-caught specimens (3), which is thought to have been largely successful, although some illegal collection from the forest is still suspected to continue (2) (6).

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

For further information on the conservation of tortoises and other reptiles see:

• International Reptile Conservation Foundation:
  www.ircf.org