7.
Delicate-skinned Salamander
(Ambystoma bombypellum)
CR
Overview
The delicate-skinned salamander was first described by herpetologist Edward Harrison Taylor from the original specimen found in 1940 on a hillside near Rancho Guadalupe, in the north-western Asunción province of Mexico. This area remains the only known area of occupancy for this species. It has been little-studied, although it is thought to feed on small invertebrates that it hunts for under rotting wood. The conservation and restoration of natural habitats for this species is essential in order to prevent its extinction across its very small area of occupancy in the wild and to provide appropriate habitat both for wild populations and any reintroduced, captive-bred individuals in the future.
Urgent Conservation Actions
Conservation and restoration of its natural habitat is urgent; new field surveys are required to assess the species’ status in the wild.
Distribution
Mexico
Fact
There are doubts about the taxonomic validity (or its definite status as a separate species) of the delicate-skinned salamander and no molecular data are currently available on this species to effectively assess these concerns. The delicate-skinned salamander was first described by herpetologist Edward Harrison Taylor from the original specimen found in 1940 near Rancho Guadalupe, 14 km east of San Martín in the north-western Asunción province in Mexico. This area remains the only known area of occupancy for this species.

The family Ambystomatidae is also referred to as the mole salamanders because many live in burrows for much of their lives. They are found only in North America (from Canada down to Mexico), the majority (like the delicate-skinned 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.
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 delicate-skinned 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 Guadalupe, 14km east of San Martín in north-western State of Mexico at an elevation of 2,500 meters above sea level. Mole salamanders are medium to large, stocky salamanders, usually 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, owing 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. 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 delicate-skinned salamander is a metamorphosing variety of Ambystomatid, which means it develops from an aquatic juvenile form with larval characteristics to a terrestrial physical form with adult features. In the adult form, the delicate-skinned salamander is a medium-sized species, with a total length of around 140 mm, about 40% of which is accounted for by the tail. This species gets its common name from the silky / shiny appearance of its skin, due to the presence of a network of fine thread-like lines. Eleven costal grooves or folds are visible in the skin along either side of the body. The fingers and toes are pointed and without webbing. The colouration is a uniform greyish-brown to lavender-brown, with a faint, narrow dark line running from the shoulder to the base of the tail. The abdomen is greyish to brownish-white and the chin is cream-yellow.
Ecology
This is a metamorphosing species, developing from the juvenile larval form to the adult terrestrial form during its lifetime. However, as with many amphibians, it must return to water bodies in order to breed and searches out ponds and small streams within its range for this purpose. 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.

The first described individuals of this species were found on a hillside near a small permanent artificial pond. They were lying under some rotten logs. The delicate-skinned salamander has been little-studied, although it probably feeds on small invertebrates that it may hunt under rotting wood.
Habitat
The majority of its time is spent on land in a mosaic of natural grasslands and pine-oak forests, living in more open habitats than the blunt-headed salamander. The species requires ponds and small streams in which to breed.
Distribution
The delicate-skinned salamander is known only from the locality where it was discovered near Rancho Guadalupe, 14km east of San Martín in the north-western Asunción province of Mexico, at 2,500m above sea level.
Population Estimate
No population data is currently available.
Population Trend
No population data is currently available, although the population trend is assumed to be in decline on the IUCN Red List of Threatened Species.
Status
Listed as Critically Endangered on the IUCN Red List of Threatened Species because its extent of occurrence is less than 100 km sq. and its area of occupancy is less than 10 km sq., all individuals are in a single subpopulation, and there is continuing decline in the extent and quality of its habitat around San Martín.
Threats
The habitat of the delicate-skinned salamander is under threat from agriculture, in particular commercial wheat farming, leading to the desiccation and pollution of its breeding lakes and water reservoirs within its small range. However, survival of this species appears to be compatible with a cattle grazing land use, particularly if stock ponds are available as surrogate breeding sites. Introduced predatory fish also pose a serious threat to the species as these may prey extensively on breeding individuals and their offspring.
Conservation Underway
The delicate-skinned salamander does not occur in any protected areas, although it is protected under the category Pr (Special Protection) by the Government of Mexico.
Conservation Proposed
Conservation and restoration of the natural habitat of the delicate-skinned salamander is urgent, and new field surveys are required to assess the status of this species in the wild. 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 might be possible to breed the delicate-skinned salamander in captivity, in which case captive animals could be a source of new individuals to repopulate natural habitats whilst its ecosystem is restored and an environmental management plan is developed for this species and its habitat. Further investigation is therefore required into the possibilities of establishing a captive breeding programme for the delicate-skinned salamander.

The conservation and restoration of natural habitats for this species is essential in order to prevent this species’ extinction across its very small area of occupancy in the wild and to provide appropriate habitat both for wild populations and any reintroduced, captive-bred individuals in the future. It is also an urgent priority to determine whether or not this species is taxonomically valid (or definitely an independent species in its own right).
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: amphibians. 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 bombypellum. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Downloaded on 08 December 2006.

Taylor, E.H. 1939. New salamanders from Mexico with a discussion of certain known forms. University of Kansas Science Bulletin 26: 407-439.

if you can provide new information to update this species account or to correct any errors, please email us at info@edgeofexistence.org


Forum comments

There are as yet no comments for this species.

Add a comment

You must log in to post. If you don't have a login, it's easy to register.