90.
Admirable False Brook Salamander
(Pseudoeurycea praecellens)
CR
Overview
The admirable false brook salamander is known only from one individual collected in 1940. It is potentially the smallest known species of false brook salamander – at a total length of 65 mm, the single collected example of this species is about 10 mm smaller than the other smallest species, the dwarf false brook salamander (which is around 75 mm long). However, this could be because the only known specimen is an immature individual. Furthermore, this species is thought to have a dubious status as a species. Since it was formally discovered in 1940 it has not been seen again, which places a certain amount of doubt upon its existence as a separate species.
Urgent Conservation Actions
Urgent fieldwork is needed in the vicinity of Cordoba, and especially the Hacienda El Potrero, to locate any habitats where this species might survive.
Distribution
Cordoba, Mexico.
Fact
The admirable false brook salamander could be the smallest known species of false brook salamander. At a total length of 65 mm, the single individual of this species that has been collected is about 10 mm smaller than the other smallest species, the dwarf false brook salamander (which reaches a length of around 75 mm). However, this could be because the only known specimen of the admirable false brook salamander was an immature individual. Furthermore, this species is thought to have a dubious status as a species. Since it was formally discovered in 1940 it has not been seen again, which places a certain amount of doubt upon its existence as a separate species. The species was initially classified as a dwarf salamander (in the genus Parvimolge, which is now only represented by a single species).
Media from ARKive
ARKive image - Admirable salamander
Evolutionary Distinctiveness
Order: Caudata
Family: Plethodontidae
The Plethodontidae is by far the largest family of salamanders, comprising nearly 70% of all living species. In total there are 378 known plethodontids divided between four subfamilies and 24 genera. The plethodontids are united by the fact that they do not possess lungs and breathe entirely through their skin and mouth lining. They are often referred to as the lungless salamanders, although they are thought to have evolved from highly aquatic, lunged ancestors in the streams of the Appalachian Mountains in eastern North America. The earliest plethodontids were hypothesised to have lost their lungs because individuals with reduced, or absent lungs were less likely to float away in the swift mountain streams where they lived. The vast majority of other salamanders possess lungs, making the lungless salamanders an unusual and fascinating group of animals.

They are thought to have diverged from all other amphibian species 145 million years ago at the boundary between the Jurassic and Cretaceous periods. They are as different from all other amphibian lineages as wombats are from whales, evolving at a time when dinosaurs were still dominant. Overall, plethodontids are the most evolutionarily advanced salamanders, so it may at first appear odd that they should have lost their lungs, which are one of the most basic features of all vertebrates living on land. Lacking lungs and being dependent on their skin for respiration places a size restriction on these salamanders because large animals have a relatively small surface area of skin compared to their body’s volume, and have greater difficulty in supplying their body tissues with oxygen compared to smaller animals (which have a large surface area to volume ratio). The long, slender form of the lungless salamanders maximises the surface area available for gas exchange, and some species grow to lengths of over 300 mm.

Plethodontid salamanders occupy a great diversity of habitats, ranging from strictly aquatic to strictly terrestrial, exploring niches as diverse as caves, trees, mountain streams, and they are also found burrowing through the earth. Dependence on their skin for breathing places limitations on where and how lungless salamanders can live. Their skin must be kept moist at all times in order for oxygen to be taken up by the blood in capillaries beneath the skin. This means plethodontids are either confined to humid areas, or must find damp hiding places and only emerge in wet weather, typically at night. The life of a lungless salamander in less humid areas, like Europe and temperate North America, therefore comprises brief periods of activity interspersed with inactive phases that are often very long. They are able to survive the periods of inactivity because they have a very low metabolic rate and low energy requirements. Able to store much of what they eat as fat, they do not need to feed very often.

A further adaptation, present among many species of the lungless salamander subfamilies named “Plethodontinae” (from East and West North America) and “Bolitoglossinae” (from tropical Central and South America), is “direct development”. This is a method of amphibian development where the larval stage (e.g. the tadpole stage in a frog’s life history) has been eliminated. Early development takes place in eggs, which may be laid in moist places away from water, and the young hatch out as miniature adults. The well known amphibian metamorphosis, most commonly appreciated in the transition from tadpole to adult frog, does not occur outside of the egg. This means that certain lungless salamanders in these two subfamilies may live away from water bodies, allowing them to expand their ranges to new areas.

The history and characteristics of the lungless salamanders go some way to explaining their range. They are mostly found in the New World, where they are widely distributed in eastern and western North America, as well as Central and South America. However, continental drift over millions of years has also brought them to the Old World, where they are found in parts of Europe (e.g. Sardinia) and Korea. The existence of the Korean crevice salamander was unknown until 2005, when its discovery was a shock to science, indicating a long history of lungless salamanders in Asia. This is the only known species in Asia, suggesting that the rate of species generation in this part of the world is very low, especially compared to the huge radiation of lungless salamander species in the New World.

Comprising 50 known species, the genus Pseudoeurycea (commonly known as the “false brook salamanders”) is one of the largest genera in the Plethodontidae family, second only to the Bolitoglossa genus (the “mushroomtongue salamanders” – 93 known species). The false brook salamanders are present within the subfamily “Bolitoglossinae” (from Central and South America) and its members are very wide ranging in size, with some of the smallest and largest lungless salamanders included (total lengths from about 65 mm to 325 mm).

The false brook salamanders have recently been reorganised and expanded to absorb a number of other genera that are now considered to fit within the Pseudoeurycea genus. The taxonomy of these salamanders may not be finally resolved just yet, but it is known that the whole group diverged from all other salamanders in the Late Eocene period, at least 34 million years ago. This is around the same time that humans and monkeys shared a common ancestor. The admirable false brook salamander may be the smallest species in its genus.
Description
The admirable false brook salamander, like all lungless salamanders in the Bolitoglossinae subfamily, possesses a slender body, long tail and prominent eyes. A distinctive feature of the plethodontid family is a narrow groove (the nasolabial groove) running from each nostril to the upper lip: its function is to carry waterborne odours from the ground into the nasal cavity. Another curious trait of the lungless salamanders are mental (from the Latin “mentum”, meaning chin) glands. These are modified mucus glands and release pheromones (chemicals produced by an animal to influence the behaviour of other members if its species, often with regard to breeding receptivity). Mental glands are sometimes visible in males as raised bumps below their lower lip.

Lungless salamanders are very small to medium in size, usually measuring between 25 to 250 mm from the tip of the nose to the end of the tail, which salamanders retain throughout their life. They are unusual among the salamanders in that some species can detach from their tail as a predator-defence mechanism (also known as tail or caudal autotomy). It is therefore not unusual to see individuals missing part or all of their tail, which they may regenerate later. Lungless salamanders may have bold patterns on their skin as adults, or they may have a colouration more similar to their environment to aid camouflage. They have well-developed “costal” grooves (successive vertical grooves in the skin along the sides of the body), generally numbering around 12-15. Their limbs are slender and often have largely or completely webbed digits. Species, like the admirable false brook salamander, in the genus Pseudoeurycea (the “false brook salamanders”) are very similar in form to those in the genera Chiropterotriton (the “splayfoot salamanders”) and Bolitoglossa (the “mushroom-tongue salamanders”).

The admirable false brook salamander is a very small species only 65 mm in total length, the tail accounting for just under half of this measurement. This species has a fairly robust body and a narrow head with small nostrils. Twelve or thirteen “costal” grooves are visible along either side of the body. The limbs are slender with minute hands and feet, and the digits are partially webbed with pointed tips. The species is brownish-black in colour, the ventral surface (or underside) being a few shades lighter. The chin and palms of the hands and feet are fairly unpigmented. White spots and blotches are present on the lower sides of the body and tail.
Ecology
Like other false brook salamanders, the admirable false brook salamander is probably active all year round and mating is thought to occur throughout the year. Some species in this genus are known to display courtship rituals. The pheromone releasing mental gland in males plays an important role in mating to influence the receptivity of females. During amplexus (the mating embrace), the male clasps the female with both his arms and legs, and rubs pheromones across the female’s snout. Fertilisation is internal and eggs will generally be laid at the beginning of the dry season in November. Female false brook salamanders have been found to guard the eggs throughout their development in many species, often in special hides, until hatching occurs at the beginning of the rainy season. Almost nothing is known about the admirable false brook salamander but it is presumed that direct development of the young occurs within the eggs and they hatch as miniature adults. This whole process is independent of a water body, making this a truly terrestrial (or land-dwelling) species.

False brook salamanders are well adapted for moving around their habitat and have prehensile tails, meaning they can use their flexible tail as a fifth limb to grip with and hang from. False brook salamanders may at first appear very vulnerable to predators but a number of defense mechanisms have been found among the members of this genus. These include: noxious skin secretions; a poisonous gland on the back of the head (parotoid glands); warning colours on the skin of the back (also termed aposematic colouration) or camouflage colouration; and caudal autotomy (tail detachment). Behaviourally, false brook salamanders have been found to orchestrate many defensive methods, including immobile posture, coiling and flipping of the body, tail undulation displays, and biting.
Habitat
The only known example of this species was collected in tropical humid forest. It is not known whether it can adapt to secondary habitats.
Distribution
Known only from Hacienda El Potrero, near the city of Cordoba, west-central Veracruz, Mexico.
Population Estimate
The admirable false brook salamander is only known from a single individual that was collected and described as a new species. Nothing further is known about its population numbers in the wild.
Population Trend
The IUCN Red List of Threatened Species indicates that the admirable false brook salamander’s total population size is assumed to be in decline. However, it has not been seen since it was originally collected on Christmas Eve in 1940. Its status as a species is uncertain.
Status
Listed as Critically Endangered on the IUCN Red List of Threatened Species because its extent of occurrence is less than 100 km sq., all individuals are in a single location, and there is continuing decline in the extent and quality of its habitat near the city of Cordoba, Veracruz, Mexico.
Threats
It is doubtful that any suitable habitat for this species remains. Since it was discovered in 1940, the city of Cordoba (the nearest large urban area to the only known locality of this species) has grown hugely. This is placing increased pressure upon the area where the admirable dwarf salamander was originally found, and there has also been extensive agricultural expansion.
Conservation Underway
The admirable false brook salamander is not known from any protected area, although it is listed as "Threatened" (Amenazada) by the Government of Mexico.
Conservation Proposed
Urgent fieldwork is needed in the vicinity of Cordoba, and especially the Hacienda El Potrero, to locate any habitats where this species might survive. If future survey work results in the discovery of surviving individuals, then the preservation and restoration of appropriate habitat is a crucial priority for the conservation of this species.

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. Further investigation is therefore required into the possibility of establishing a captive breeding programme for any surviving admirable false brook salamanders. Captive animals could then be a source of new individuals to repopulate any restored habitat.
Links
References
AmphibiaWeb: Information on amphibian biology and conservation [web application]. 2006. Berkeley, California: AmphibiaWeb. Available: amphibiaweb. Accessed: 08 December 2006.

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Duellman, W. E. and Trueb, L. 1986. Biology of Amphibians. McGraw-Hill, New York.

Dunn, E. R. 1926. The salamanders of the family Plethodontidae. Smith College, Northampton, Massachusetts, U.S.A..

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

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.

Halliday, T. and Adler, C. (eds.). 2002. The new encyclopedia of reptiles and amphibians. Oxford University Press, Oxford.

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

Larson, A. 1991. A molecular perspective on the evolutionary relationships of the salamander families. Evolutionary Biology 25:211-277.

Larson, A. and Dimmick, W.W. 1993. Phylogenetic relationships of the salamander families: A analysis of congruence among morphological and molecular characters. Herpetological Monographs 7:77-93.

Macey, J. R. 2005. Plethodontid salamander mitochondrial genomics: A parsimony evaluation of character conflict and implications for historical biogeography. Cladistics 21:194-202.

Min, M. S., Yang, S.Y., Bonett, R.M., Vieites, D. R., Brandon, R.A. and Wake, D.B. 2005. Discovery of the first Asian plethodontid salamander. Nature 435:87-90.

Mueller, R. L., Macey, J.R., Jaekel, M., Wake, D.B. and Boore, J.L. 2004. Morphological homoplasy, life history evolution, and historical biogeography of plethodontid salamanders inferred from complete mitochondrial genomes. PNAS 101:13820-13825.

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.

Parra Olea, G. & Wake, D. 2004. Pseudoeurycea praecellens. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Downloaded on 11 December 2006.

Parra-Olea, G., García-París, M. and Wake, D.B. 1999. Status of some populations of Mexican salamanders. Revista de Biologia Tropical 47: 217-223.

Rabb, G.B. 1955. A new salamander of the genus Parvimolge from Mexico. Breviora 42: 1-9.

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.

Wake, D. B. 1966. Comparative osteology and evolution of the lungless salamanders, family Plethodontidae. Memoirs of the Southern California Academy of Sciences 4:1-111.

Wake, D. B. and Larson, A. 1987. Multidimensional analysis of an evolving lineage. Science 238:42-48.

Wake, D. B. and Lynch. J.F. 1976. The distribution, ecology and evolutionary history of plethodontid salamanders in tropical America. Natural History Museum of Los Angeles County Science Bulletin 25:1-65.

Wake, D.B. and Elias, P. 1983. New genera and a new species of Central American salamanders, with a review of the tropical genera (Amphibia, Caudata, Plethodontidae). Natural History Museum of Los Angeles County - Contributions in Science 345: 1-19.

Wake, D.B. and Lynch, J.F. 1976. The distribution, ecology, and evolutionary history of plethodontid salamanders in tropical America. Science Bulletin of the Natural History Museum of Los Angeles County 25: 1-65.

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