Anderson's salamander (''Ambystoma andersoni'') is a

neotenic Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny in modern humans is more signif ...

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 ...

from Zacapu Lagoon in the

Mexican state A Mexican State (), officially the Free and Sovereign State (), is a constituent federative entity of Mexico according to the Constitution of Mexico. Currently there are 31 states, each with its own constitution, government, state governor, a ...

Michoacán Michoacán, formally Michoacán de Ocampo, officially the Free and Sovereign State of Michoacán de Ocampo, is one of the 31 states which, together with Mexico City, compose the Political divisions of Mexico, Federal Entities of Mexico. The stat ...

. This salamander is a relatively recent discovery, first described by Branden and Krebs in 1984. ''Ambystoma andersoni'' is named after James Anderson, a

herpetologist Herpetology (from Ancient Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is a branch of zoology concerned with the study of amphibians (including frogs, salamanders, and caecilians (Gymnophiona)) and reptiles (in ...

with the

American Museum of Natural History The American Museum of Natural History (AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. Located in Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 21 interconn ...

, who did extensive fieldwork studying ''Ambystoma'' and other amphibians and reptiles in Mexico. Like all neotenic ''Ambystoma'' species, ''A. andersoni'' retains its

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

l features into adulthood. The mature salamander has medium-sized

external gills External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a fri ...

with bright red filaments, and a prominent

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

. It has a large head and small limbs, as do the larvae. Its coloration is a strange pattern of black blotches on a red-brown base. The salamanders are totally aquatic and spend their whole lives in the same body of water.

Habitat

Lake Zacapu is a small lake near Zacapu, sitting at an altitude of 2000 meters. The lake is located within the Mesa Central portion of Mexico, an area home to many neotenic ''Ambystoma'' species. It is

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

, with low

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

, and has a single stream originating from it. ''Ambystoma andersoni'' is listed as

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 ...

on the IUCN Red List. Andersons salamander distrubution

References

* Database entry includes a range map and justification for why this species is critically endangered {{Taxonbar, from=Q491418 Mole salamanders Amphibians described in 1984