Description
Chiropterotriton aureus is a small, narrow-body salamander described from one male and three females. The average snout-vent lengths are 26.8 ± 0.86 mm for females and 28.5 mm for males. Total lengths are about 36.5 mm for males and 31.1 ± 1.41 mm for females (García-Castillo et al. 2018; Parra Olea et al. 2020). Chiropterotriton aureus has a narrow head with a slim and box-shaped snout, although the width of the head is greater than the shoulder width. The nostrils are oval-shaped. The mental gland was described in the male as small and round. There is an occurrence of a sublingual fold. Both eyes stick out of its head. Just like its body, the limbs of this species are also small and narrow with similarly slender digits. The outer digit is longer on the hands and feet. The pharyngeal formula is 1 - 2 - 3 - 2 on the hands and 1 - 2 - 3 - 3 - 2 on the feet with the shortest digit being the first and longest being the third on both the hands and feet. The digits taper at the tip, and this species has subterminal pads. There is a moderate amount of webbing on the second to last phalanx. This species also has an unusually large tail that is longer than the snout-vent length. Lastly, their limbs, when adpressed along the body, are separated by 2.0 and 2.3 costal folds in males and females, respectively (García-Castillo et al. 2018).

DIAGNOSIS:

At the time of the species description, there were 16 known species in the genus Chiropterotriton. Chiropterotriton aureus has key differences in its head, body, and limbs that differentiate it from the other species in the genus. Overall, C. aureus is a smaller and more slender species than others in the genus Chiropterotriton. One exception being that C. aureus differs from C. perotensis due to the former's larger size. However, C. aureus still has a longer tail and narrower head and feet than C. perotensis. Small size, narrow head, short limbs, long tail, and narrow feet differentiate C. aureus from C. ceronorum, C. melipona and C. totonacus. Chiropterotriton melipona also has longer limbs than C. aureus. Chiropterotriton aureus is smaller than C. casasi, although C. aureus does have a longer tail. Chiropterotriton casasi also has a longer head, longer limbs, and wider feet. Chiropterotriton chiropterus is larger, has longer limbs, a broader head, and larger feet when compared to C. aureus. Relative to C. orculus, C. aureus has a smaller body size, longer tail, smaller and narrower head, longer limbs in the female specimens, and narrower feet. Chiropterotriton lavae is overall larger, has longer limbs, and a broader head and feet (Parra Olea et al. 2020).

COLORATION:

In life, the dorsal side of the head ranges from buff, yellow, or dark red with a lighter yellow at the snout, and parts of the eyelids. The gular region and lateral region is pale in color. The dorsal surface of the body is yellowish-orange with hints of green. There is a conspicuous line on the side of the body separating the yellowish-orange color from a darker black-gray color. The tail follows a similar pattern but gets progressively darker with light-colored speckling. The ventral side of the tail is pale in color. The feet and hands are nearly translucent with primarily beige fore- and hind limbs. The iris is orange-brown (García-Castillo et al. 2018).

In alcohol, the dorsal side is drab and while the ventral side is a lighter drab color (García-Castillo et al. 2018).

VARIATION:

There is little variation between the specimens used to describe the species (García-Castillo et al. 2018).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

A native to Veracruz, Mexico, C. aureus is only known to occur from the type locality in Atzalan on the western side of Sierra de Chiconquiaco, within Sierra Madre Oriental. Recorded at an elevation of 1,249 meters, their estimated extent of occurrence is 10 km² (García-Castillo et al. 2018, Parra Olea et al. 2020). The species could occur more widely, albeit only in the contiguous vicinity (since other species in the genus are micro-endemics). In totality, the estimated extent of occurrence of C. aureus is unlikely to surpass 2,000 km² (IUCN 2020). Chiropterotriton aureus is found in arboreal bromeliads on oaks of cloud forests. It has been recorded in agricultural fields, although only in fields adjacent to forest (García-Castillo et al. 2018). In effect, their ideal habitat is a subtropical to tropical, moist montane forest.

Life History, Abundance, Activity, and Special Behaviors

A terrestrial species, C. aureus is found in arboreal bromeliads on oaks of cloud forests (García-Castillo et al. 2018). Salamanders in the Chiropterotriton genus are noted to typically engage in more activity, particularly foraging behaviors, during the night and spend the day in between dark, moist leaves. However, since C. aureus has been found in bromeliads, this suggests that instead of spending the day in between leaves, they could be residing in fallen logs or sinks (Perez-Ponce de Leon et al. 2011).

Assuming C. aureus displays similar reproductive biology and trends as other members of this genus, these salamanders partake in a fully terrestrial lifestyle, and females become sexually mature when they reach approximately two years and are typically 35 mm in size (Perez-Ponce de Leon et al. 2011; Rabb 1958).

Five Chiropterotriton sp. females were found with what scientists believed to be spermatophores in their cloacas, suggesting internal fertilization (Rabb 1958). This genus lays non-aquatic eggs in hidden spots such as bromeliads, underneath mosses, and in tree liverworts, where direct development occurs (Perez-Ponce de Leon et al. 2011). A different species in this genus (C. bromeliacia) has been observed to produce a clutch size ranging from 6 - 20 eggs, with larger females typically producing more eggs (Houck 1977).

Salamanders display an array of defense postures, maneuvers, and other tactics to avoid predation. Species in the genus Chiropterotriton have been noted to exhibit flipping behaviors and becoming immobile. Interestingly, Chiropterotriton salamanders showed an increased duration of remaining immobile at extreme temperatures, indicating that, at optimal temperatures, running or flipping away from predators is more advantageous (Dodd and Brodie 1976).

Trends and Threats
The population trend is uncertain; as of 2018, C. aureus was only known from five specimens from a single locality (García-Castillo et al. 2018). However, there is speculation that this species may naturally occur at lower densities (IUCN 2020).

Currently, agriculture activities are the premiere threat to this species as, small-holder farming, grazing, and ranching have depreciated ideal habitat and displaced the C. aureus population. Although disruption is not ideal, C. aureus has shown tolerance for some habitat disturbance. Hence, its presence in adjacent agricultural fields. However, it likely relies on the cloud forest for survival. Thus, continued habitat modification from aforementioned threats forwards a decline in an already depauperate species (IUCN 2020).

Additionally, potential infection from the salamander chytrid fungus, Batrachochytrium salamandrivorans (Bsal), has caused great concern. Although not yet introduced to South America, this virulent amphibian pathogen has caused significant declines in European salamanders (Feldmeier et al. 2016), and its continued proliferation in Europe raises concern. C. aureus’ type locality is highly suitable for Bsal, and should the fungus arrive, infection and decline would be imminent (Basanta et al. 2019, Mexico Red List Assessment Workshop October 2019).

Possible reasons for amphibian decline

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

Comments

PHYLOGENETIC RELATIONSHIPS:

At the time of the species description, Chiropterotriton consisted of 16 species, one being the newly described C. aureus. Based on Bayesian and Maximum Likelihood analyses of 1,477-bp matrix from two mitochondrial fragments, L2 (which includes 12S, tRNA, and 16S genes) and COI, as well as morphological characters, C. aureus has been distinguished as a unique species. Chiropterotriton aureus is sister to the clade composed of C. chiropterus, C. nubilus, and an undescribed species (García-Castillo et al. 2018).

Phylogenetic reconstructions of this genus have discriminated two primary Chiropterotriton assemblages, correlating to southern and northern distributions. Chiropterotriton aureus is a member of the southern assemblage (García-Castillo et al. 2018).

ETYMOLOGY

The species epithet, “aureus” is a derivative of the Latin word “aurum” meaning “gold” and the derivational suffix “-eus.” Together, the name means “made of gold, gold in color”, in reference to the unique dorsal characteristic of this species. This reference is also found in its common name: Atzalan Golden Salamander (García-Castillo et al. 2018).

References

Basanta, M.D., Rebollar, E.A., Parra-Olea, G. (2019). "Potential risk of Batrachochytrium salamandrivorans in Mexico." PloS one 14(2): e0211960. [link]

Dodd, C. K. Jr., and Brodie, E. D. Jr. (1976). ''Defense mechanisms of neotropical salamanders with an experimental analysis of immobility and the effect of temperature on immobility.'' Herpetological Monographs, 32, 269-290.

Feldmeier, S., Schefczyk, L., Wagner, N., Heinemann, G., Veith, M., Lötters, S., Gratwicke, B. (2016). “Exploring the distribution of the spreading lethal salamander chytrid fungus in its invasive range in Europe - a macroecological approach.” PloS one, 11(10), e0165682. [link]

García-Castillo MG, Soto-Pozos ÁF, Aguilar-López JL, Pineda E, Parra-Olea G. (2018). “Two new species of Chiropterotriton (Caudata: Plethodontidae) from central Veracruz, Mexico.” Amphibian and Reptile Conservation 12(2) [Special Section]: 37–54 (e167). [link]

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.

IUCN SSC Amphibian Specialist Group. (2020). "Chiropterotriton aureus". The IUCN Red List of Threatened Species 2020: e.T150088930A150088935. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T150088930A150088935.en. Accessed on 07 February 2022.

Parra Olea, G., Garcia-Castillo, M. G., Rovito, S. M., Maisano, J. A., Hanken, J., Wake, D. B. (2020). “Descriptions of five new species of the salamander genus Chiropterotriton (Caudata: Plethodontidae) from eastern Mexico and the status of three currently recognized taxa.” PeerJ, 8:e8800 [link]

Pérez-Ponce de León, G., Mendoza-Garfias, B., Razo-Mendivil, U., Parra-Olea, G. (2011). "A new genus and species of Brachycoeliidae (Digenea) from Chiropterotriton sp. (Caudata: Plethodontidae) in Mexico and its phylogenetic position within the Plagiorchiida based on partial sequences of the 28S ribosomal RNA gene." Journal of Parasitology, 97(1), 128–134. [link]

Rabb, G. B. (1958). ''On certain Mexican salamanders of the plethodontid genus Chiropterotriton.'' Occasional Papers of the Museum of Zoology, 587, 1-37.

Species Account Citation: AmphibiaWeb 2022 Chiropterotriton aureus: Atzalan Golden Salamander; Salamandra Dorada de Atzalan <https://amphibiaweb.org/species/8950> University of California, Berkeley, CA, USA. Accessed Apr 19, 2024.

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

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