The flat-backed spider tortoise (''Pyxis planicauda''), more commonly known as the flat-tailed tortoise, and Madagascan flat-tailed tortoise, is a tortoise that belongs to the family

Testudinidae Tortoises ( ) are reptiles of the family Testudinidae of the order Testudines (Latin for "tortoise"). Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like ot ...

. The various common names for this small tortoise usually refer to the noticeably flattened nature of its oblong upper-shell or its tail. The flat-backed spider tortoise is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the west coast of Madagascar, between the Monrondava and Tsiribihina rivers. Due to the specifications of its habitat, the flat-backed spider tortoise is classified as critically endangered on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is an inventory of the global conservation status and extinction risk of biological ...

Description

The flat-backed spider tortoise receives its name from its distinctive physical appearance. Its upper-shell (

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

) and tail are outstandingly flatter than the common tortoise. Its carapace is patterned, with each

scute A scute () or scutum (Latin: ''scutum''; plural: ''scuta'' "Scutum (shield), shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of Bird anatomy#Scales, birds. The ter ...

ranging in color from light brown to yellow center and a dark brown to black outline. In older tortoise, an additional yellow border can be seen that surrounds the dark outline. Yellow rays extend outwards from the center of each scute. Scutes along the borders of the shell (marginal) are usually dark in color, surrounded by a yellow band. The lower shell (

plastron The turtle shell is a shield for the ventral and dorsal parts of turtles (the Order (biology), order Testudines), completely enclosing all the turtle's vital organs and in some cases even the head. It is constructed of modified bony elements such ...

) usually appears to be yellow in color, with scattered dark spots or rays. The limbs are covered with scales that range from yellow to brown in color. The head, on the other hand, is usually darker in color (ranges from dark brown to black, with some yellow markings).

Habitat and behavior

The flat-backed spider tortoise is confined to lowland fragments of dry, deciduous forest, found only on the west coast of Madagascar. It is concentrated between the Monrondava and Tsirbihina rivers. The forests inhabited by the flat-backed spider tortoise grow on loose sandy soils and the tortoises take shelter amongst the leaf litter of the forest floor during their inactive seasons. The flat-backed spider tortoise is active only during the warm/raining season (December–March), with most activity concentrated during and after rain. During the cooler dry season the flat-backed spider tortoise enters a stage similar to

hibernation Hibernation is a state of minimal activity and metabolic reduction entered by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It is mos ...

known as

aestivation Aestivation ( (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered m ...

, the species buries itself and lies dormant. Mating season usually takes place during the hot/rainy season, and is followed a month later by egg-laying. Females may produce up to three clutches a year, each containing only one relatively large egg. Hatching is therefore timed with the return of the rainy season, when the species is most active.

Threats

Due to its habitat restrictions, the flat-backed spider tortoise is considered to be critically endangered . Its major threat comes from habitat loss due to the process of

deforestation Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. Ab ...

, particularly from burning and clearing for agricultural lands/cattle grazing, highway development, mining, and petroleum exploration. A combined forest habitat loss of 70% has been estimated for the period (1963-2040).
Another threat arises from the collection for pet trade. Pet trade is estimated to have removed about 4,000 adults during 2000 to 2002, representing 20 to 40% of the total number of adults (depending on the estimated population of adults). The reproductive nature of this species does not make it eligible of excessive pet trading since they are particularly low even by tortoise standards, with females producing up to three clutches a year consisting only of one egg each.

References

External links

{{Taxonbar, from=Q1426275 Pyxis (genus) Endemic fauna of Madagascar Reptiles of Madagascar Turtles of Africa Critically endangered fauna of Africa Reptiles described in 1867 Taxa named by Alfred Grandidier Taxonomy articles created by Polbot