Cofre de Perote Salamander (Pseudoeurycea naucampatepetl)
Known only from five individuals, very little information is available about the ecology of the Cofre de Perote salamander. The species has only been found beneath the surface of roadside banks, suggesting that it is a burrowing species. Specimens that have been dug from the roadside banks were observed rolling out onto the ground and becoming languid at the cooler temperatures (13�C) outside of the bank. This species may therefore burrow to conserve its heat energy at the high altitudes where it is found. It has not been seen for over 20 years, despite searches (including very thorough surveys in 2003 and 2004) and it is thought that this species could be extinct.
Distribution
Sierra Madre Oriental, Mexico.
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 to 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.
Description
The Cofre de Perote salamander, like all lungless salamanders in the Bolitoglossinae subfamily, possess 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 individuls 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 between 12-15. Their limbs are slender and often have largely or completely webbed digits. Species, like the Cofre de Perote 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 Cofre de Perote salamander is a relatively large species, reaching a total length of 120-150 mm, with the relatively short tail accounting for 75-85% of this measurement. The tail is slender and tapers to a blunt tip. This is a fairly robust species that has a large, prominent head with protruding eyes, a broadly rounded snout and visible mental glands. It has 13 “costal” grooves in the skin along either side of the body. From the very small sample of Cofre de Perote salamanders that have been measured, it appears that males and females are the same size.
Limbs are long and robust with large hands and feet. The digits are elongated, well-developed, unwebbed, and have pads on the tips. This is a strikingly coloured species, being solidly black with bright pink to pinkish-cream spots along the dorsal (or upper) surface arranged in a characteristic pattern. There are rounded spots behind the eyes, triangular spots on the back just behind the forelimbs, eleven pairs of small spots along the back in roughly the same spacing as the costal grooves, and large U-shaped spots at the junction between the body and the tail. The stomach and ventral surface (or underside) is pale to dark grey and the mental glands are pale grey.
Ecology
Very little is known about the ecology of the Cofre de Perote salamander because the species is only known from five individuals. However, this species has only been found beneath the surface of roadside banks, suggesting that it is fossorial (or burrowing). Specimens that have been dug from the roadside banks were observed rolling out onto the ground and becoming languid at the cooler temperatures (13�C) outside of the bank. This species may therefore burrow to conserve its heat energy at the high altitudes where it is found.
Like other false brook salamanders, the Cofre de Perote 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. Very little is known about the Cofre de Perote 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. This may prove particularly useful in arboreal (or tree-dwelling) species, although the Cofre de Perote salamander’s burrowing lifestyle may also benefit from a strong, flexible tail. 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 Cofre de Perote salamander lives in pine-oak forests with abundant bunch grass at an altitude of 2,500-3,000 metres above sea level. This species is only known from a narrow ridge extending east from Cofre de Perote and terminating in a small peak, Cerro Volcancillo, where the first individuals were found. The ridge is vegetated with pine-oak woodland, including alder and bunch grass in cleared areas. Because of the extensive cutting of the forest, most of the trees are now fairly small, although some large firs are present in remnants of original vegetation, which have now been largely replaced by secondary forest. All the Cofre de Perote salamanders discovered so far have been found by scraping the surface of roadside banks, consisting of moist soil with a dry outer crust, under which the salamanders were found. This species is therefore fossorial (or burrowing) and most of the banks where this species have been found were shaded. The remaining habitat of the Cofre de Perote salamander is very degraded, which might explain why it can no longer be found.
Distribution
The Cofre de Perote salamander is only known from along a narrow ridge that runs between two mountain peaks. The ridge extends east from Cofre de Perote and ends at Cerro Volcancillo in the Sierra Madre Oriental in central Veracruz, Mexico. The altitudinal range of this species is 2,500-3,000 metres above sea level.
Population Estimate
There is very little information available on the population status of the Cofre de Perote salamander. It is known from five specimens, and has not been seen for over 20 years, despite searches (including very thorough surveys in 2003 and 2004) and it is even thought that this species could already be extinct.
Population Trend
The Cofre de Perote salamander is considered to be in decline by the IUCN Red List of Threatened Species. The species has not been seen for over 20 years and may already be exinct.
Status
Listed as Critically Endangered 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, and in the number of mature individuals, in east-central Veracruz, Mexico.
Threats
The main threat to the Cofre de Perote salamander is the destruction of its original habitat caused by extensive logging, farming (especially potatoes), and expanding human settlements. Its habitat has been extensively modified in the past 20 years, during which time this species has not been seen at all.
Conservation Underway
The Cofre de Perote salamander is not known from any protected areas and there are currently no conservation measures underway to protect this species.
Conservation Proposed
Protection of the forested areas that still remain in the Cofre de Perote area is a priority. Further survey work is also required to determine the current population status of the species, and whether it survives in the wild.
Furthermore, 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 of 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 possibilities of establishing a captive breeding programme for any surviving Cofre de Perote salamanders. Captive animals could then be a source of new individuals to repopulate any restored habitat.
Links
AmphibiaWeb
Global Amphibian Assessment
Tree of Life Web Project
References
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