7.
Granular Salamander
(Ambystoma granulosum)
CR
Overview
The granular salamander, like many of its close relatives, is a metamorphosing species of mole salamander belonging to the genus Ambystoma. It inhabits the grasslands located in a small area on the north-western periphery of Toluca city in the central State of Mexico at 3,000m above sea level. The small number of species that represent the Ambystoma are highly evolutionarily distinct members of both the salamanders and the amphibians as a whole. Introduced predatory fish are a major threat to the granular salamander, but its habitat has also been heavily impacted due to extensive urban and agricultural expansion, which has led to the desiccation and pollution of its breeding habitat.
Urgent Conservation Actions
Creation of unpolluted breeding pools and the protection of key sites of grassland and breeding water bodies in the north-western periphery of Toluca city.
Distribution
Mexico
Fact
The family Ambystomatidae is also referred to as the mole salamanders because many live in burrows for much for their lives. They are found only in North America (from Canada down to Mexico). The majority (like the granular salamander) metamorphose from aquatic larvae to become terrestrial adults that are rarely seen except in the breeding season, when they migrate to ponds to mate and deposit eggs.
Associated Blog Posts
18th Jun 12
The granular salamander (Ambystoma granulosum) is a very unusual EDGE species. Belonging to the Ambystomatidae (or “mole salamander”) family, which diver...  Read

Evolutionary Distinctiveness
Order: Caudata
Family: Ambystomatidae
The family Ambystomatidae or “the mole salamanders” is included within the four earliest or most primitive family lineages of the order “Caudata” (the salamanders), diverging from all other salamanders in the Early Cretaceous period over 140 million years ago, around five million years before the koala and dolphin lineages diverged from their common ancestor. The small number of species that represent the genus Ambystoma are highly evolutionarily distinct members of both the salamanders and the amphibians as a whole.

The granular salamander, like many of its close relatives, is a metamorphosing species of mole salamander. It therefore develops into an adult form, losing its larval characteristics such as gills and fins, and developing adult traits such as eyelids and functioning lungs. It returns to ponds in order to breed.
Description
An Ambystomatid or mole salamander known only from a small area on the north-western periphery of Toluca city in the central State of Mexico at an elevation of 3,000m above sea level. Mole salamanders are medium to large, stocky salamanders, measuring between 90 to 350mm from the tip of the nose to the end of the tail, which salamanders retain throughout their life. Males are often larger than females, partly due to their longer tails. Ambystomatids generally exhibit both aquatic “neotenic” larval (or aquatic and permanently juvenile in form with external, feathery gills) and terrestrial “metamorphosed” (or ground-dwelling, fully developed adult in form with reduced gills) stages in their wild populations. Ambystomatids are often boldly patterned as adults, with well-developed costal grooves (successive vertical grooves along the sides of the body), especially the metamorphosing varieties. They have a rather flattened body with a wide, flattened head, a large mouth and smooth skin with many glands. The tail is roundish or laterally compressed, and, during the breeding season, males have a very swollen cloacal zone (the region around the reproductory and excretory opening in amphibians located underneath the base of the tail).

The granular salamander is a metamorphosing variety of mole salamander, which means it develops from an aquatic juvenile form with larval characteristics to a terrestrial physical form with adult features. It is similar to the delicate-skinned salamander (EDGE species 10), but has a shorter, more elevated tail. This species is around 140-170mm in length, the tail accounting for 60-80mm of this measurement. The skin of the dorsal (or upper) surface is corrugated or granular, especially along the tail, which explains why this species’ common name is the granular salamander. Twelve costal grooves are visible in the skin along either side of the body and they may also be traced across the abdomen. The limbs are of moderate length, and the finger and toes are unwebbed and pointed. The granular salamander is greenish or yellow-olive to brown-olive in colouration and has numerous small black spots across the dorsal surface of its body and tail. It has a paler yellowish to yellowish-brown underside free from any markings.
Ecology
The granular salamander is a metamorphosing species of Ambystomatid, developing into a terrestrial (or ground-dwelling) adult form that spends most of its time on land in a grassland habitat. This species, like many amphibians, returns to water to breed, which the granular salamander does in small pools and ponds, both artificial and natural.

Once the eggs are laid in water they are left to develop with no further participation by either parent. This species does not exhibit parental care.
Habitat
The grasslands located in a small area on the north- western periphery of Toluca city in central State of Mexico at 3,000m above sea level. The species breeds in small pools and ponds, both artificial and natural, found within its grassland habitat.
Distribution
Known only from a small area on the north-western periphery of Toluca city, central State of Mexico, Mexico, at 3,000m above sea level.
Population Estimate
There is currently no information available on the population status of the granular salamander.
Population Trend
No population data are currently available, although the population trend is assumed to be in decline in the IUCN Red List of Threatened Species.
Status
Listed as Critically Endangered in the IUCN Red List of Threatened Species because its extent of occurrence is less than 100km sq., all individuals are in a single subpopulation, and there is continuing decline in the extent and quality of its habitat on the north-western periphery of Toluca City.
Threats
Introduced predatory fish are the major threat to the granular salamander, but the habitat has also been heavily impacted due to extensive urban and agricultural expansion. This has led to the desiccation and pollution of the granular salamander’s breeding habitat.
Conservation Underway
The granular salamander does not occur in any protected areas, so the conservation and restoration of its remaining habitat is an urgent priority in order to prevent its extinction in the wild. However, this species is protected under the category Pr (Special Protection) by the Government of Mexico.
Conservation Proposed
A survey is urgently needed to determine the current population status of the granular salamander in the wild. Conservation and restoration of the species’ habitat is an urgent priority in order to save this species from extinction in the wild. In addition to conserving wild habitat for this species, the IUCN Technical Guidelines for the Management of Ex situ Populations, part of the IUCN Red List of Threatened Species, recommend that all Critically Endangered species should have an ex situ population managed to guard against the extinction of the species. An ex situ population is ideally a breeding colony of a species maintained outside its natural habitat, giving rise to individuals from that species that are sheltered from problems associated with their situation in the wild. This can be located within the species’ range or in a foreign country that has the facilities to support a captive breeding programme for that species. It is not known whether it is possible to breed this species in captivity so further investigation is therefore required into the possibilities of establishing an ex situ breeding programme for the granular salamander.

However, any ex situ conservation measure is rendered ineffective if there remains insufficient natural habitat in which to release captive bred populations in the future. Clearly protected areas, sensitive land use techniques, habitat restoration and the control of introduced predatory fish populations are of paramount importance to rescuing this Critically Endangered mole salamander from extinction in the wild. The creation of unpolluted breeding pools and the protection of key sites of grassland and breeding water bodies in the north-western periphery of Toluca city are therefore the primary actions required for the preservation of this species.
Links
References
AmphibiaWeb: Information on amphibian biology and conservation [web application]. 2006. Berkeley, California: AmphibiaWeb. Available: amphibiaweb. Accessed: 08 December 2006.

Frost, Darrel R. 2006. Amphibian Species of the World: an Online Reference. Version 4 (17 August 2006). Electronic Database accessible at: . American Museum of Natural History, New York, USA.

Frost, D. R., T. Grant, J. Faivovich, R. H. Bain, A. Haas, C. F. B. Haddad, R. O. De Sá, A. Channing, M. Wilkinson, S. C. Donnellan, C. J. Raxworthy, J. A. Campbell, B. L. Blotto, P. Moler, R. C. Drewes, R. A. Nussbaum, J. D. Lynch, D. M. Green, and W. C. Wheeler. 2006. The Amphibian Tree of Life. Bulletin of the American Museum of Natural History 297: 1-370.

IUCN, Conservation International and NatureServe. 2006. Global Amphibian Assessment. Global Amphibian Assessment. Accessed on 08 December 2006.

Obst, F.J., Richter, K. and Jacob, U. 1984. The Completely Illustrated Atlas of Reptiles and Amphibians for the Terrarium. T.F.H. Publication Inc., N.J., U.S.A.

Roelants, K., Gower, D. J., Wilkinson, M., Loader, S. P., Biju, S. D., Guillaume, K., Moiau, L. and Bossuyt, F. 2007. Global patterns of diversification in the history of modern amphibians. Proceedings of the National Academy of Sciences 104: 887-892.

Shaffer, H.B. 1984. Evolution in a paedomorphic lineage. I. An electrophoretic analysis of the Mexican ambystomatid salamanders. Evolution 38: 1194-1206.

Shaffer, H.B. 1984. Evolution in a paedomorphic lineage. II. Allometry and form in the Mexican ambystomatid salamanders. Evolution 38: 1207-1218.

Shaffer, B., Flores-Villela, O., Parra Olea, G. & Wake, D. 2004. Ambystoma granulosum. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Downloaded on 08 December 2006.

Taylor, E.H. 1944. A new ambystomatid salamander from the plateau region of Mexico. The University of Kansas Scientific Bulletin 20(1): 57-61.

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