Angulate tortoise
The angulate tortoise (Chersina angulata) is a species of tortoise found in dry areas and coastal scrub vegetation in South Africa. This tortoise is the only known member of the genus Chersina.
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.[4]
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.
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.[5]
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.[6]
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.
