Description
Pseudoeurycea rex shows sexual dimorphism, where females are larger than males. Males reach maturity at snout-vent lengths of 35 – 39 mm, and have an average adult snout-vent length of 46 mm. Females reach maturity at snout vent lengths of 42 – 50 mm and adults average 49 mm in snout-vent length (Houck 1977). The bluntly oval head is longer than wide. The snout is swollen and the nostrils are small. There is a tubercle below the nostrils. The diameter of the eye is longer than the distance from the snout to the eye. The eyelids fold under skin behind the eye. From the lateral view, the upper jaw appears slightly concave. There are teeth on the maxilla and nine vomerine teeth that extend beyond the nostrils. There are a total of 12 - 13 costal grooves. The limbs are well developed. When the legs are appressed, there are 2 – 4 costal grooves left exposed. The digits have minimal webbing at the base and are not very flat. The relative finger lengths are 3 > 2 > 4 > 1 and the toes are 3 > 4 > 2 > 5 > 1. The base of the circular tail is constricted and the tail itself is longer than the snout-vent length. The anal lips have palpillae (Dunn 1921).

In life, individuals are dark with an almost black coloration, their dark coloration is likely to be a form of crypsis (Dodd Jr and Brodie Jr 1976). Dunn (1921) describes the species as having pinkish gray coloration on dorsum and dorsal surfaces of the limbs and tail, gray colorations on the lateral surfaces that is marbled with white, and light grey on the ventrum with white marbling on the throat and dorsal surface of the snout.

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Guatemala, Mexico

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (2 records).

Pseudoeurycea rex is found in the Sierra de los Cuchumatanes in southwestern Guatemala. It occurs on Volcan Tacana on the border between Mexico and Guatamala. It can be found in altitudes from 2,450 to 4,000 meters above sea level, and it most commonly found higher than 2,800 meters above sea level (Acevedo et al. 2008).

Life History, Abundance, Activity, and Special Behaviors
Pseudoeurycea rex is fully terrestrial at higher elevations and can be found in leaf litter, under logs, and under moss mats. In cloud forests however, from 1,500 - 2,750 meters above sea level, individuals can commonly be found in bromeliads (Wake 1987). When found, individuals will most commonly stay still, using immobility to dissuade predators. When further threatened they will elevate and undulate their tails (Dodd Jr and Brodie Jr 1976).

Pseudoeurycea rex is a terrestrial breeder with direct developing larvae (Houck 1977).

Trends and Threats
Pseudoeurycea rex was previously a very common species in Guatemala however in recent years there has been a significant decline in capture rates (Rovito et al. 2009). This decline coincides with the rise of the chytrid fungus, Batrachochytrium dendrobatidis (Bd), among Mexican amphibian populations (Cheng et al. 2011). Estimates made in 2011 show a 12% prevalence of chytrid in the species’ remaining populations (Cheng 2011).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Disease

Comments
The species authority is: Dunn, E.R. (1921). Two new Central American salamanders. Proc. Biol. Soc. Wash. 34, 143–145.

The species was first named Oedipus rex by Emmett Reid Dunn in 1921.

Blankers et al. (2012) preformed a large analysis using phylogenies from other studies, morphometric data, and microhabitat use. They showed that P. rex, P. exspectata, P. brunnata form a clade.

References

Acevedo, M., Wake, D., Vasquez, C., Rovito, S. 2008. Pseudoeurycea rex. The IUCN Red List of Threatened Species 2008: e.T59392A11916292. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T59392A11916292.en. Downloaded on 21 June 2017.

Blankers, T., Adams, D.C., Wiens, J.J. (2012). ''Ecological radiation with limited morphological diversification in salamanders.'' Journal of Evolutionary Biology, 25, 634–646.

Cheng, T.L., Rovito, S.M., Wake, D.B., Vredenburg, V.T. (2011). ''Coincident mass extirpation of neotropical amphibians with the emergence of the infectious fungal pathogen Batrachochytrium dendrobatidis.'' Proc. Natl. Acad. Sci., 108, 9502–9507.

Cheng, T.L.T. (2011). Impacts of an amphibian pathogen, Batrachochytrium dendrobatidis, in Mesoamerica and Taiwan. Master's Thesis. San Francisco State University.

Dodd, C. K., Jr. and Brodie, E. D., III (1976). ''Defensive mechanisms of Neotropical salamanders with an experimental analysis of immobility and the effect of temperature on immobility.'' Herpetologica, 32(3), 269-290.

Dunn, E.R. (1921). ''Two new Central American salamanders.'' Proc. Biol. Soc. Wash., 34, 143–145.

Houck, L.D. (1977). ''Life history patterns and reproductive biology of neotropical salamanders.'' The Reproductive Biology of Amphibians. Taylor, D.H., Guttman, S.I., eds., Springer, New York, New York, 43–72.

Rovito, S., Parra-Olea, G., Vásquez-Almazán, C. R., Papenfuss, T. J., and Wake, D. B. (2009). ''Dramatic declines in neotropical salamander populations are an important part of the global amphibian crisis.'' Proceedings of the National Academy of Sciences of the United States of America, 106(9), 3231-3236.

Wake, D. B. (1987). ''Adaptive radiation of salamanders in Middle American cloud forests.'' Annals of the Missouri Botanical Garden, 74(2), 242-264.

Species Account Citation: AmphibiaWeb 2017 Pseudoeurycea rex <https://amphibiaweb.org/species/4186> University of California, Berkeley, CA, USA. Accessed Nov 19, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 19 Nov 2024.

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