Angulate tortoise

Angulate tortoise
In South Africa
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Testudines
Suborder:	Cryptodira
Family:	Testudinidae
Genus:	Chersina
Species:	C. angulata
Binomial name
Chersina angulata (Schweigger, 1812)
Synonyms
List Testudo angulata Schweigger, 1812 Testudo bellii Gray, 1828 Chersina angulata Gray, 1831 Neotestudo angulata Hewitt, 1931 Goniochersus angulatus Mertens, Müller & Rust, 1934 Chersine angulata Hewitt, 1937 Goniocherus angulatus Mertens & Wermuth, 1955

The angulate tortoise (Chersina angulata) or bowsprit tortoise is a species of tortoise found in dry areas and coastal scrub vegetation in South Africa. It is the only living member of the genus Chersina.

Etymology

Internationally it is known by the two names of "angulate" and "bowsprit" tortoise. Locally in southern Africa however, it is uniformly known as the "angulate" tortoise in English, and as the rooipens skilpad ("red-belly tortoise") in Afrikaans.

Taxonomy

This species is highly distinctive and is now classified by itself, in the monotypic Chersina genus. While it differs considerably from all other tortoise species, its closest relatives, according to phylogenetic studies, are the tiny "padloper" (Homopus) tortoise species, with which it shares its southern African habitat.

Distribution and habitat

Their natural habitat is the fynbos, karoo, albany thickets and coastal scrub (strandveld) vegetation of the south-western part of South Africa. This is an area of semi-arid and Mediterranean climate, with winter rainfall. Within this climatic range however, the angulate tortoise is a tough and very adaptable species.

Geographically, this natural range extends across the Cape Floristic Region, as far north as the southern part of Namibia. In addition, small colonies have been introduced by tourists to domestic gardens in Swakopmund and Walvis Bay, even further north, in central Namibia. To the east, its range extends along the Cape's southern coast as far as East London. There is also an especially dense colony on Dassen Island, off the South African coast. Throughout its range, this tortoise usually occurs in the greatest numbers near the coast. Inland it occurs at lesser densities, though smaller populations are even found in parts of the Karoo.

Description

Identification

A small, shy tortoise with a relatively variable shell, they can often be distinguished by their prominent "bowsprits", which are protrusions of the "gular" shields, from their plastrons under their chins. These are used by males to fight for territory or females. Uniquely, this species has only one gular shield under its chin; all other southern African tortoises have a divided/double scaled gular. Angulate specimens have five claws on their front legs and four on each back leg. They also, like most other southern African tortoises, have a nuchal scute.

Regional variation

There is considerable regional variation in this species of tortoise. Angulates from the west coast of southern Africa tend to have a reddish colour, especially on the underside of their shell (from where their Afrikaans name of rooipens or "red-belly" comes). Inland specimens from the Karoo region are often darker, and some are known to be uniformly black. To the east of their range, individuals are typically smaller and have a lighter colour. Such tendencies can be diluted by admixture however, and in all populations individuals tend to assume a uniform brown colour in old age.

Sexual dimorphism

This species shows considerable difference between male and female individuals. The male angulates tend to be larger, to have concave bellies, and to have a longer, thinner, "peanut" shape. They also have enlarged and extended gular scutes under their chins, which they use for sparring with each other.

The females tend to be smaller and rounder, with a flat or slightly convex belly. Males tend to have a cream-coloured mark on top of their head^{[citation needed]}

Ecology

Within its natural range, the natural predators of the species include mongoose, jackals, badgers, baboons and predatory birds which attack the infants. Perhaps the largest killers of this species in its natural habitat are the periodic wildfires, which can kill hundreds of thousands at a time.

Conservation

Due to human activity, it is also increasingly threatened by habitat destruction from agriculture and other development, as well as illegal collecting for the pet trade and deaths from tortoises crossing busy roads. Human introduced species such as the pied crow kill thousands of infants every year, especially along the West Coast where this invasive species is rapidly spreading.

The angulate tortoise is commonly kept as a garden pet in South Africa. However the species is classified as "Protected Wild Animal" in the Nature Conservation Ordinance No. 19 (1974), and it is therefore strictly illegal to remove this animal from the wild. It may also not be transported, possessed, imported or exported without a permit.

A commonly reported problem is that, when a tortoise is spotted crossing rural roads, drivers tend to stop, pick it up and take it home - away from its habitat in the wild. This is illegal and traumatic for the tortoise. Instead drivers are encouraged to stop and, if they wish, assist it crossing the road in the direction that it was going.

Nonetheless, there is a legal and regulated pet trade in this tortoise, especially for captive-bred specimens. However it is absolutely imperative to attain a permit when buying, selling or keeping this species.

References

Wikimedia Commons has media related to Chersina angulata.

• at Honoluluzoo.org
• Christopher Lever (2003). Naturalized Reptiles and Amphibians of the World. Oxford University Press. p. 22. ISBN 978-0-19-850771-0.
• Chelonia.org^{[link removed]}