Description
Eleutherodactylus manantlanensis is a moderately-sized frog described from 14 adult male specimens with a snout-to-vent length between 25.1 to 28.9 mm and vocal slits present. The tympanum is very small, round, and indistinct in live individuals, a characteristic that distinguishes E. manantlanensis from its congeners. Its skin is non-translucent and thus there is no visible ventral abdominal vein in life. The limbs are moderate in size with a femur length ranging from 11.13 to 12.66 mm. The 3rd and 4th finger pads are extended. The dorsal skin varies from a smooth to pustulate texture while both the lateral and ventral skin are only smooth (Grünwald et al. 2018).

DIAGNOSIS:

Eleutherodactylus manantlanensis can be distinguished from others in the North American mainland Eleutherodactylus genus of the Syrrhophus subgenus through a variety of features. From E. longipes by E. manatlanensis having an opaque abdominal epidermis lacking a visible ventral vein and the absence of a visible annulus or distinct tympanum. It can be discerned from the E. nitidus species group by the presence of extended 3rd and 4th finger pads, pustulate skin, pale interorbital bar, and the absence of a compact, projecting lumbar gland in the inguinal area. From the E. modestus species group, it can be distinguished by a combination of pustulate skin, expanded finger tips, bright inguinal coloration on the thighs, and lack of compact, projecting lumbar glands above the inguinal region. It is most similar to E. nietoi, from which E. manantlanensis is distinguishable by having a larger size, less pustulate dorsum, lack of distinct tympanum, and pale-colored upper arms (Grünwald et al. 2018).

COLORATION:

In life, the dorsal coloration can vary from pale to dark brown, tan, or yellow. The shoulders have pale-colored “saddle blotches” and a similarly colored interorbital bar at the top of its head. The tibia, tarsus, and forearms have dark-colored transverse bars while the upper arms are pale-colored and usually lack dark markings. The ventrum is grey-colored with white-colored spots or flecking (Grünwald et al. 2018).

VARIATION:

At the time of their species description, there was little observed variation in the morphology or coloration. Some individuals may have fiery orange flash coloration present in the inguinal region, hind legs, and flanks (Grünwald et al. 2018).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

At the time of their species description, E. manantlanensis was known only from the immediate locale near the municipality of Minatitlán, Colima and may be endemic to the eastern limestone formations of the Sierra de Manantlán mountain range on the border of southwestern Jalisco and northern Colima in Western México. It is found above 2000 meters and associated with karstic oak (Quercus) or pine (Pinus) woodland habitat (Grünwald et al. 2018).

Life History, Abundance, Activity, and Special Behaviors
The advertisement call of E. manantlanensis males is a multi-note “trill” consisting of nine rapid note trills of 257 milliseconds on average and a starting frequency of 3,470 kHz rising to 3,750 kHz (Grünwald et al. 2018).

Larva
Along with its Eleutherodactylus congeners, the species is assumed to breed by direct development (IUCN 2020).

Trends and Threats
An Environmental Vulnerability Score assessment developed by Wilson and McCranie (1992) and adapted by Porras et al. (2013) gave E. manantlanensis a high score of 15 at the time of its description due its extremely limited range and moderately specialized reproductive mode (Grünwald et al. 2018). Considering the combined threats from continued decline in habitat area and quality, E. manantlanensis is listed as “Critically Endangered” by the IUCN (2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Introduced competitors
Disease

Comments

PHYLOGENETIC RELATIONSHIPS:

Maximum likelihood and Bayesian inference methods on 16S rRNA, CytC oxidase subunit 1, and CytB data supports the placement of the E. modestus clade as the sister clade to the subclade containing E. manantlanensis along with E. teretistes, E. jaliscoenses, and E. grünwaldi (Hernández-Austria 2022).

ETYMOLOGY:

The genus name, “Eleutherodactylus,” is derived from the Greek word for “free-toed” (Dodd 2013).

The species epithet, “manantlanenses,” is named for the incredibly biodiverse Sierra de Manantlán, where the species is likely endemic to, of the Sierra Madre del Sur that stretches from southwestern Jalisco to northern Colima (Grünwald et al. 2018).

References

Dodd, C. K. 2013. Frogs of the United States and Canada. John Hopkins University: JHU Press.

Grünwald, C. I., Reyes-Velasco, J., Franz-Chávez, H., Morales-Flores, K. I., Ahumada-Carrillo, I. T., Jones, J. M., Boissinot, S. (2018). “Six new species of Eleutherodactylus (Anura: Eleutherodactylidae: subgenus Syrrhophus) from Mexico, with a discussion of their systematic relationships and the validity of related species.” Mesoamerican Herpetology, 5, 6-83. [link]

Hernández-Austria, R., García-Vázquez, U. O., Grünwald, C. I., Parra-Olea, G. (2022). “Molecular phylogeny of the subgenus Syrrhophus (Amphibia: Anura: Eleutherodactylidae), with the description of a new species from Eastern Mexico.” Systematics and Biodiversity 20(1), 1-20. [link]

IUCN SSC Amphibian Specialist Group. (2020). "Eleutherodactylus manantlanensis." The IUCN Red List of Threatened Species 2020: e.T151283927A151283945. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T151283927A151283945.en. Accessed in May 2022

Porras, l. W., Wilson, l. D., Schuett, G. W., Reiserer, R. S. (2013). "A taxonomic reevaluation and conservation assessment of the common cantil, Agkistrodon bilineatus (Squamata: Viperidae): a race against time." Amphibian & Reptile Conservation 7, 48-73. [link]

Wilson, L. D., McCranie, J. R. (1992). "Status of amphibian populations in Honduras." Unpublished report to the task force on declining amphibian populations. 14 p.

Species Account Citation: AmphibiaWeb 2023 Eleutherodactylus manantlanensis: Sierra Manantlán Trilling Frog <https://amphibiaweb.org/species/8842> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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