The marginated tortoise (Testudo marginata) is a species of tortoise in the family Testudinidae. The species is endemic to Greece, Italy, and the Balkans in Southern Europe. It is the largest European tortoise. The marginated tortoise is herbivorous, and brumates for the winter.
Taxonomy
The marginated tortoise was formally described by German naturalist Johann David Schoepff in 1789; its specific epithet marginata is a straightforward derivation from the Latin term for 'marginated'. The nominate subspecies is the Greek marginated tortoise, Testudo marginata marginata. Three additional subspecies of marginated tortoises have been named: The Sardinian marginated tortoise (T. m. sarda) is the name usually used to separate the population on the island of Sardinia. These tortoises have less strongly bent tiles in the posterior of their carapaces, and the posterior of the carapace is almost smooth compared with the saw-like T. m. marginata. Clearly distinct according to morphology and entirely allopatric, it cannot be distinguished by mtDNA cytochrome b and nDNA ISSR sequence analysis. Lineage sorting has not occurred to a considerable degree; consequently, the more geographically isolated Sardinian population is presumably of quite recent origin. Indeed, it appears to derive from a deliberate introduction by humans. Though it is not clear whether this occurred in prehistoric times or more recently, this might be resolved by dating subfossil remains. Sequence evolution at least in mtDNA is known to proceed much more slowly in some turtles and tortoises than in others; the rate of the mitochondrial 12S rRNA gene in Testudo is probably a rather low 1.0–1.6% per million years (as this fits best the paleobiogeographical situation), limiting the resolution provided by molecular systematics. An extinct subspecies described as T. m. cretensis persisted on Crete before the end of the last ice age, presumably larger than mainland tortoises. However, numerous additional fossils have since refuted the validity of this subspecies. A population of small and light-colored marginated tortoises exists on the southwestern coast of the Peloponnesus, between Kalamata and south of Stoupa. The so-called "dwarf marginated tortoise" was described as a new species Testudo weissingeri, but it is not recognizably distinct phylogenetically. Unlike the Sardinian population, it occupies an extremely restricted range with very arid habitat, and its apomorphies seem related to this. Considering ice age-associated climate and sea level changes, this population is probably not older than a few thousand years; as it is not geographically isolated, it should be considered a local form, and not even a subspecies T. m. weissingeri. Notably, a similar situation is found in Hermann's tortoises living in the same region. Testudo marginata is also closely related to the Greek or common tortoise (Testudo graeca). Both have very similar bodily characteristics—oblong carapaces, large scales on the front legs, large coverings for the head and cone-like scales on the upper thighs, undivided tail coverings, moveable stomach plates, and lack of tail spikes. Presumably, Testudo marginata diverged from ancestral Testudo graeca as a population more suited for life in the mountainous regions. Evidence in favor of this is the wide geographical region and the extremely large number of subspecies of Testudo graeca, including a subspecies in Turkey with strongly bent carapace tiles, like the marginated tortoise. Testudo marginata on the other hand, despite the two subspecies, presents a much more unified appearance, which points toward an earlier appearance in evolutionary history. In captivity, the two species often cross-breed, but this should be avoided. According to the 2005 DNA sequence data, these species do not seem to hybridize to a notable extent in the wild, though they are obviously very close relatives, and as evidenced by morphology, some allele flow still occurs, but slowly. The Egyptian tortoise appears to represent a lineage that diverged from the same ancestral stock southwards into northeastern Africa around the same time as the marginated tortoise's ancestors diverged in Greece. These two are actually more similar to each other than to T. graeca regarding DNA sequence data, but considering biogeography, this is either due to (rather unlikely) dispersal across the Mediterranean, or the supposed "clade" is invalid and the similarity due to convergent evolution.
Description The marginated tortoise is the largest European tortoise, reaching a weight of up to 5 kg (11 lb) and a length of 35 cm (14 in). Its shell is oblong and has a notable thickness around the middle of the body. The posterior end of the shell has a saw-like formation, flanged outward like a bell. The carapace of an adult specimen is almost completely black, with yellow highlights. The ventral shell is lighter-coloured and has pairs of triangular markings with the points facing the rear of the animal. The front sides of the limbs are covered with large scales. In an old female specimen, the rear flaps of the underside of her plastron is somewhat moveable. The tail is notable for a lengthwise marking and for an undivided carapace over the tail. The male has a longer tail, which is thicker at the base than the female's. The underside is more strongly indented. Males are also often larger than the females. The females lay their hard-shelled spherical eggs in the soil in May and June.
Distribution and habitat
The natural range of the marginated tortoise is southern Greece, from the Peloponnesus to Mount Olympus. They are also found in isolated zones of the Balkans and Italy, and northeastern Sardinia. The marginated tortoise lives in more mountainous regions than Hermann's tortoise. It can be found in elevations as high as 1,600 m (5,200 ft). The black color of the carapace is helpful for survival in this environment, as it allows the tortoise to absorb a great deal of heat in a short time, helping it maintain its body temperature. Early in the morning, marginated tortoises bask in the sun to raise their body temperature, and then search for food. After feeding, the tortoises return to their shelters in the hot midday hours, leaving them again in the late afternoon.
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