Bolitoglossa is a genus of salamanders, also called tropical climbing salamanders or web-footed salamanders, in the Plethodontidae family. Their range is Central and South America: Mexico, Colombia, Venezuela, Ecuador, Peru, northeastern Brazil, and central Bolivia. These arboreal and terrestrial, Neotropical salamanders of the Bolitoglossa genus make up the largest genus in the order Caudata consisting of approximately one-fourth of all known species of salamanders. Adult salamanders range anywhere from 45mm to 200mm in length depending on their specific species. They are notorious for their webbed feet, as indicated from their name, and have significantly more webbing than any other species outside their genus with the exception of the Cave-dwelling Mexican Bolitoglossine Chiropterotriton magnipes. Although webbed feet are a common characteristic of these salamanders, only about half of the species in this genus contain webbed feet.
Hand and foot morphology
Hand and foot morphology is strikingly diverse in an otherwise morphologically uniform group. While just under half of these species contain webbing between their fingers and toes, the remaining species experience little to no webbing and undergo elongation of their fingers and toes throughout development. Ultimately, the variation of foot morphology within this genus is primarily due to natural selection. Derived characteristics correspond to arboreal vs. terrestrial salamanders.
- Webbed fingers – natural selection to improve terrestrial movement through water.
- Elongated fingers – natural selection of increased suction efficiency, favoring a larger surface area of the foot. This also selects for a decreased body size, enabling the salamander to cling trees more easily.
Tail autotomy refers to the salamanders’ ability to release or loose their tail if necessary. This is a common characteristic of nearly all salamanders and lizards. (See autotomy). It is particularly helpful to the salamander in escaping attacks from its predators. Once the tail has been lost, it can regenerate one time. After this regeneration, the tail is incapable of separation with regeneration.
B. rostrata and B. subpalmata are two rare examples of poisonous salamanders within their genus. The poison is secreted through their skin as an antipredator mechanism. It is particularly toxic to certain snake species, rendering them immobile and unresponsive to external stimuli upon initial contact. The common defense tactic of these two species is to remain still in the presence of the snake until it makes initial contact (usually by the flickering of its tongue), and then run away as the paralytic poison begins to take effect in the snake.
Tropical adaptation of the Bolitoglossa genus is thought to have evolved from N. American Plethodontids. Natural selection is responsible for morphological changes shifting from those supporting temperate environments to those supporting tropical environments such as Panama and Costa Rica. Natural selection is thought to have resulted in genetic changes from physical adaptation. The main differences that have developed from natural selection affect the skull and bones of the feet in these salamanders. Due to these primary changes, secondary changes are believed to have followed, including:
- Body size
- Additional ossification of bones
- Ear structure
The first documented case of hybridization in tropical salamanders occurred between B. frankini and B. resplendens. This hybridization has taken a pervasive effect on the morphology of B. resplendens, whereas B. frankini seemed to maintain its same physical structure. According to scientists, this is the only known salamander hybrid in the world today.
Derived characteristics of the genus Bolitoglossa has led to their classification based on this specific list of characters:
- Tongue and hypobranchial apparatus
- Epibranchial Number
- embryos having a single epibranchial
- Tail Autotomy
- Brain stem motor control
- Bone structure of Jaws, Cranial, and inner ear
- Chromosome number
- diploid number of chromosomes is 26
Classification of this genus is primarily accomplished through analysis of the salamanders’ DNA. This has proven to be the most effective and accurate way of classifying this genus.
117 species are currently assigned to this genus.
- Alberch, Pere. "Convergence and Parallelism in Foot Morphology of the Neotropical Salamander Genus Bolitoglossa." Evolution 35.1 (1981): 84-100.
- "Jaekel, Martin, and David Wake. "Developmental processes underlying the evolution of a derived foot morphology in salamanders." PNAS 104.51 (2007): 20437-20442."
- Brodie, Edmund, and Peter Ducey. "Salamanders Respond Selectively to contacts with Snakes: Survival Advantage of Alternative Antipredator Strategies." Copeia 1983.4 (1983): 1036-1041.
- Brodie, Edmund, Jr. and Peter K. Ducey. "Antipredator Skin Secretions of Some Tropical Salamanders (Bolitoglossa) are Toxic to Snake Predators." Biotropica 23.1 (1991): 58-62.
- Ortega, Jesus E., John Murry Monares-Riano, and Martha Patricia RamIrez-Panilla. "Reproductive Activity, Diet, and Microhabitat Use in Bolitoglossa nicefori (Caudata: Plethodontidae)." Journal of Herpetology 43.1 (2009): 1-10. BioOne Online Journals. Web. 6 Dec. 2010.
- Alberch, Pere. "Morphological Variation in the Neotropical Salamander Genus Bolitoglossa." Evolution 37.5 (1982): 906-919.
- Wake, David B., Suh Y. Yang, and Theodore J. Papenfuss. "Natural Hybridization and its Evolutionary Implications in Guatemalan Plethodontid Salamanders of the Genus Bolitoglossa." Herpetologica 36.4 (1980): 334-344.
- Devitt, Tom and David Wake. 2007. supergenus Bolitoglossa. Version 09 March 2007 (under construction). http://tolweb.org/supergenus_Bolitoglossa/68802/2007.03.09 in The Tree of Life Web Project, http://tolweb.org/
- Frost, Darrel R. 2008. Amphibian Species of the World: an Online Reference. Version 5.2 (15 July, 2008). Bolitoglossa. Electronic Database accessible at http://research.amnh.org/herpetology/amphibia/index.php. American Museum of Natural History, New York, USA. (Accessed: July 29, 2008).
- AmphibiaWeb: Information on amphibian biology and conservation. [web application]. 2008. Berkeley, California: Bolitoglossa. AmphibiaWeb, available at http://amphibiaweb.org/. (Accessed: July 29, 2008).
- Tree of Life: Bolitoglossa