''Thorius aureus'', the golden thorius, is a species of

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Thorius ''Thorius'', also known as minute salamanders, pigmy salamanders, or Mexican pigmy salamanders, is a genus of salamanders in the family Plethodontidae. They are endemic to Mexico and found in southern Veracruz and Puebla to Guerrero and Oaxaca. ...

'', the Mexican pigmy salamanders, part of the

lungless salamander Plethodontidae, or lungless salamanders, are a family of salamanders. With over 500 species, lungless salamanders are by far the largest family of salamanders in terms of their diversity. Most species are native to the Western Hemisphere, from B ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

. It 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 mountainous areas of north central Oaxaca State in Mexico. It is one of the largest ''Thorius'' species.

Etymology

The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

''aureus'', Latin for golden or splendid, refers to the distinctive golden dorsal stripe that is characteristic of the species.

Description

''Thorius aureus'' is a slender salamander with a narrow head and long tail. However, among ''Thorius'' it counts as a large and robust species, with males measuring and females in snout–vent length. The tail is relatively long and can be up to 1.16 times the snout–vent length in males. It grows to a total length of about and is one of the largest species in the genus. Females have a rounded snout but this is more pointed in males. The eyes are protuberant and the nasolabial grooves distinct. The nostrils are small and oval and the upper jaw contains teeth (these are absent in many other members of the genus). The limbs are short with slender hands and feet. The digits are partially fused but are free at the tips. The dorsal surface is light brown and there is a distinctive broad golden stripe running along the spine, widest on the head and back and narrower at the shoulders. There are several brown chevron-shaped markings on the stripe.

Distribution and habitat

''Thorius aureus'' is found in a restricted area around the peak of Cerro Pelón on the northern slopes of the

Sierra Juárez, Oaxaca The Sierra Juárez is a range of mountains in Oaxaca state, Mexico between latitudes 17°20'-17°50'N and longitudes 96°15'-97°00'W, with an area of about . It is part of the Sierra Madre de Oaxaca. The range is separated from the Sierra de Zon ...

, Mexico, at altitudes of between above sea level. It lives among the leaf litter on the forest floor of mixed woodland of oak, fir and pine and also in

cloud forest A cloud forest, also called a water forest, primas forest, or tropical montane cloud forest, is a generally tropical or subtropical, evergreen, Montane forest, montane, Tropical and subtropical moist broadleaf forests, moist forest characteri ...

s. Being nocturnal, it hides during the daytime under rocks and fallen timber.

Biology

Little is known of the biology of this species. It is believed to feed on grubs, insects and other small invertebrates found among the leaf litter or under the bark of rotting logs. No

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

have been observed but they are thought to be laid on land and to undergo direct development into juvenile salamanders without passing through a larval stage.

Status

''Thorius aureus'' is listed as being "

Critically Endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...

" by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

in its

Red List of Threatened Species 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 spe ...

. This is because, although at one time common within its range, by 2008 no populations could be located, with only one sighting in the previous few years. Normally a resident of

virgin forest An old-growth forest or primary forest is a forest that has developed over a long period of time without Disturbance (ecology), disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organizati ...

, it does not adapt well to living in secondary growth, but the amount of logging within its range is insufficient to account for its dramatic population decline, which remains unexplained.

References

{{DEFAULTSORT:Thorius Aureus

aureus The ''aureus'' ( ''aurei'', 'golden') was the main gold coin of ancient Rome from the 1st century BC to the early 4th century AD, when it was replaced by the ''solidus (coin), solidus''. This type of coin was sporadically issued during the Roman ...

Amphibians described in 1994 Endemic amphibians of Mexico Fauna of the Sierra Madre de Oaxaca Taxonomy articles created by Polbot