Description
Bolitoglossa coaxtlahuacana is a small salamander described from only two male specimens, an adult and a smaller sub-adult. The adult measures 41.8 mm from snout to vent. The rounded snout measures 3.1 mm and extends beyond the mandible. The nostrils are small and located near the tip of the snout. There is a nasolabial groove that extends from the bottom of the nostril to the lip. The eyes bulge slightly, but are not visible from the ventral view. There are deep suborbital grooves and distinct postorbital grooves. The salamander has no mental gland, and cephalic and dermal glands are not visible. There are thirteen costal grooves on each side. Its slender limbs are separated by two costal grooves when adpressed along the body. There is moderate webbing on both the hands and feet with the third digit on each having less webbing than the others. This species has distinct digital pads. The tail is 32.2 mm long (Palacios-Aguilar et al. 2020).

The species can be distinguished from species belonging to other genera of neotropical salamanders by its lack of a sublingual fold. It is distinguished from other Bolitoglossa species by its discrete digits that expand distally and have distinct subterminal pads. It is also distinguished from other species by its smaller size, lack of a mental gland, and divergent nucleotide sequences. More specifically, B. coaxtlahuacana is different from other Bolitoglossa (Oaxakia) species in the following ways: B. caoxtlahuacana has a smaller body and a shorter tail than B. macrinii, the species it was originally classified under, as well as a broader head, narrower feet, smaller eyes, and fewer vomerine teeth. It differs from B. oaxacensis by its smaller body, shorter limbs, fewer vomerine teeth, and black dorsal coloring. A smaller body, shorter tail, shorter limbs, smaller head, narrower feet, and fewer maxillary and premaxillary teeth in B. coaxtlahuacana distinguished it from B. zapoteca (Palacios-Aguilar et al. 2020).

In life, B. coaxtlahuacana has black dorsal and tail coloring. The dorsal side of the hands and feet as well as the snout and lips are brown. The irises are a golden color with red flecks near the pupil. The ventral side of the salamander is lighter. The bottom of the hands and feet are a gray color, and the underside of the chin is brown. It seems that the species may be able to change its color to a small degree, shifting between a black purple color and a dark gray on its ventral side. In alcohol, its coloration is mostly unchanged. However, the ventral side becomes more opaque and white iridophores become visible (Palacios-Aguilar et al. 2020).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

Bolitoglossa coaxtlahuacana is known from specimens found in a mountain range that covers most of Mochitlán, Guerrero, Mexico. These mountains have humid oak forests as well as areas that resemble cloud forests with similar vegetation and dominant tree species that can be tropical or temperate. Both specimens were found 1800 m above sea level (Palacios-Aguilar et al. 2020).

Life History, Abundance, Activity, and Special Behaviors
Both specimens of B. coaxtlahuacana were found at night on bushes near a mountain stream after heavy rains in mid-July. The holotype was dissected and had large fat deposits that suggest reproductive activity (Palacios-Aguilar et al. 2020).

They showed slow movements and used their prehensile tails to hold onto the vegetation (Palacios-Aguilar et al. 2020).

Larva
Like other plethodontids, B. coaxtlahuacana is presumed to be a direct developer.

Trends and Threats
A closely related species to B. coaxtlahuacana, B. macrinii, is categorized as “Endangered” by the IUCN Red List. Bolitoglossa macrinii is in decline due to threats including its habitat being cleared for residential and urban development, agriculture of non-timber crops, and logging. It has not been observed in any protected areas (IUCN 2019). Because B. coaxtlahuacana is closely related to B. macrinii and lives in a similar environment, it most likely faces many of the same threats as B. macrinii, possibly to a greater degree since not much is known about the natural population.

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Urbanization

Comments

PHYLOGENETIC RELATIONSHIPS:

Bayesian inference analysis of the mitochondrial genes, 16S and cytb, has shown B. coaxtlahuacana to be most closely related to the clade composed of B. riletti and B. hermosa. It is next most closely related to B. zapoteca, then to the clade composed of B. macrinii and B. oaxacensis (Palacios-Aguilar et al. 2020).

ETYMOLOGY:

The species epithet, “coaxtlahuacana,” refers to the village of Coaxtlahuacán, Guerrero, where samples of this species were obtained (Palacios-Aguilar et al. 2020).

References

IUCN SSC Amphibian Specialist Group. (2019). "Bolitoglossa macrinii." The IUCN Red List of Threatened Species 2019: e.T59176A53976241. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T59176A53976241.en. Accessed on 31 August 2022

Palacios-Aguilar, Cisneros-Bernal, A. Y., Arias-Montiel, J. D., and Parra-Olea, G. (2020). “A new species of Bolitoglossa (Amphibia: Plethodontidae) from the central highlands of Guerrero, Mexico.” Canadian Journal of Zoology, 98(6), 359–365. [link]

Species Account Citation: AmphibiaWeb 2022 Bolitoglossa coaxtlahuacana: Coaxtlahuacán Salamander <https://amphibiaweb.org/species/9181> 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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