''Chelonoidis niger microphyes'', also known as the Volcán Darwin giant tortoise, Darwin Volcano giant tortoise or Tagus Cove giant tortoise, is a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

Galápagos tortoise The Galápagos tortoise or Galápagos giant tortoise (''Chelonoidis niger'') is a species of very large tortoise in the genus ''Chelonoidis'' (which also contains three smaller species from mainland South America). It comprises 15 subspecies (13 ...

endemic Endemism is the state of a species being found 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 found elsew ...

to the Galápagos archipelago in the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...

ial eastern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

''microphyes'' (“small when full-grown”) is based on the mistaken assumption by describer

Albert Günther Albert Karl Ludwig Gotthilf Günther FRS, also Albert Charles Lewis Gotthilf Günther (3 October 1830 – 1 February 1914), was a German-born British zoologist, ichthyologist, and herpetologist. Günther is ranked the second-most productive re ...

that the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen (with a carapace length of only 57.2 cm) was of an adult male.

Taxonomy

This tortoise is a subspecies of ''Chelonoidis niger'', and is sometimes considered to be a distinct species of its own. The type locality is Tagus Cove, near the base of Darwin Volcano on Isabela Island.

Description

Male tortoises grow to about 135 cm and females to about 86 cm in length, with domed

carapace A carapace is a Dorsum (biology), 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 tor ...

Behaviour

The tortoises are mainly active in the early morning and late afternoon, resting in shade during the hottest part of the day and sleeping beneath shrubs at night. After heavy rain they wallow in muddy pools. Adults migrate seasonally from the

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

of the

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

to its lower slopes to graze on vegetation after wet season rains.

Feeding

The tortoises feed on grass, leaves, berries and

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.cacti A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

in the dry season.

Breeding

Male tortoises compete with each other by extending their necks, gaping, biting and pushing. They utter loud guttural noises while mating. Females start nesting in May and June at the end of the wet season.

Distribution and habitat

The tortoise's range is limited to an area of about 67 km² on the south-western slope of Darwin Volcano on the northern part of Isabela Island. There it inhabits deciduous and evergreen forests as well as dry

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

Conservation

The tortoise population is estimated to comprise some 500–1,000 mature individuals, a decline of 94% since 1840, and the subspecies is considered to be

Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

. The tortoises were historically overexploited for food and oil by sailors and settlers. Ongoing threats include predation of eggs and hatchlings and competition for food by introduced animals, including

feral dog A free-ranging dog is a dog that is not confined to a yard or house. Free-ranging dogs include street dogs, village dogs, stray dogs, feral dogs, etc., and may be owned or unowned. The global dog population is estimated to be 900 million, of w ...

feral cat A feral cat or a stray cat is an unowned domestic cat (''Felis catus'') that lives outdoors and avoids human contact: it does not allow itself to be handled or touched, and usually remains hidden from humans. Feral cats may breed over dozens ...

rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include ''Neotoma'' ( pack rats), ''Bandicota'' (bandicoot ...

mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

domestic pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus s ...

s and

goat The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...

s, as well as habitat degradation and volcanic eruptions.

References

{{Taxonbar, from= Q12745312 microphyes Subspecies Turtles of South America Endemic reptiles of the Galápagos Islands Reptiles of Ecuador Taxa named by Albert Günther Reptiles described in 1875