Atoyac Minute Salamander
Thorius infernalis is distinguished from similar species in this genus by its relatively long tail in comparison to its small body size, shorter limbs, pointed toe tips with fused toes, and narrower head with a more pointed snout. It is differentiated from T. omiltemi and T. grandis, which are the other Thorius species found in Guerrero, Mexico, by its small size, and lack of maxillary teeth. When compared to T. minutissimus, T. infernalis can be differentiated by having less protuberant nostrils and lacking rounded toe tips. It is distinguished from T. pennatulus, T. narismagnus, and T. smithi, by lacking rounded nostrils (Hanken et al. 1999).
In life, the sides are fairly dark. A pale stripe runs from the back of the neck down to the tail, though it fades in color as it reaches the tail. The underside is lighter than the sides, and is noticeably lighter at the throat. In preservative, it is golden brown overall, though with darker sides and a lighter back and underside. A faint stripe runs from the head to the base of the tail. The throat is spotted white, with markings interspersed throughout the underside. Its irises are gray (Hanken et al 1999).
The male has one premaxillary tooth and five vomerine teeth, whereas the female lacks premaxillary teeth and has seven vomerine teeth (Hanken et al 1999).
Distribution and Habitat
Life History, Abundance, Activity, and Special Behaviors
Trends and Threats
Possible reasons for amphibian decline
General habitat alteration and loss
As there are only two known specimens to represent this species, no molecular analysis has been conducted to genetically compare this species to others. However, Thorius species can be grouped by the presence of maxillary teeth, which T. infernalis lacks. This absence of maxillary teeth is thought to represent an ancestral trait among the genus, suggesting that T. infernalis is a more ancestral species within Thorius (Hanken et al. 1999, Rovito et al. 2013).
The species epithet, infernalis, is derived from Latin meaning “of the lower world” and refers to the lower elevation in which this species was found. Its common name refers to the nearby city of Atoyac de Álvarez, which is among the hottest geographical locations in North America (Hanken et al. 1999).
Further surveys are needed to determine if this species still exists in the wild. Field verification is needed to better predict potential distributional ranges in order to effectively protect land that is suitable for T. infernalis in hopes of saving the species (Ochoa-Ochoa et al. 2009).
Hanken, J., Wake, D. B., Freeman, H. L. (1999). ''Three New Species of Minute Salamanders (Thorius: Plethodontidae) from Guerrero, México, Including the Report of a Novel Dental Polymorphism in Urodeles.'' Copeia, 1999(4), 917-931.
Ochoa-Ochoa, L., Urbina-Cardona, J. N., Vázquez, L.-B., Flores-Villela, O., and Bezaury-Creel, J. (2009). ''The effects of governmental protected areas and social initiatives for land protection on the conservation of Mexican amphibians.'' PLoS One, 4(9), e6878.
Parra-Olea, G., Wake, D., García-París, M., Hanken, J. (2008). Thorius infernalis. The IUCN Red List of Threatened Species. Version 2014.3. www.iucnredlist.org. Downloaded on 22 March 2015.
Rovito, S. M., Parra-Olea, G., Hanken, J., Bonett, R. M., Wake, D. B. (2013). ''Adaptive radiation in miniature: the minute salamanders of the Mexican highlands (Amphibia: Plethodontidae: Thorius).'' Biological Journal of the Linnean Society, 109, 622-643.
Wake, D. B. and Hanken, J. (1996). ''Direct development in the lungless salamanders: what are the consequences for developmental biology, evolution, and phylogenesis?'' International Journal of Developmental Biology, 40, 859-869.
Written by Jennifer Schoener (jenschoener AT gmail.com), University of Nevada, Reno
First submitted 2015-08-11
Edited by Gordon Lau (2015-09-28)
Species Account Citation: AmphibiaWeb 2015 Thorius infernalis: Atoyac Minute Salamander <http://amphibiaweb.org/species/5358> University of California, Berkeley, CA, USA. Accessed Jul 2, 2020.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 2 Jul 2020.
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