Description
Eleutherodactylus erythrochomus is a moderate sized frog with a snout-vent length range of 20.1 - 30.9 mm. The head is slightly longer than it is wide, and the width is as wide as its body. In the dorsal view, the snout is subacuminate and it is rounded in lateral view. The tympanum is visibly beneath the skin and has a distinct annuli and membrane, but lacks a supratympanic fold. Its skin is smooth, both dorsally and ventrally. The fingers are slender with just a slight distinctive fleshy flare on the margins and with expanded, but truncated disks on the tips. The relative finger lengths are as follows: I > II > III < IV (Palacios-Aguilar and Santos-Bibiano 2020). For more description, please see Palacios-Aguilar and Santos-Bibiano 2020.

DIAGNOSIS:

Eleutherodactylus erythrochomus is morphologically different from others in its genus by its enlarged disks on the hands that are three times wider than the narrowest part of the digit. Additionally, it has a wider tympanum and head than species such as E. colimotl, E. floresvillelai, E. manantlanensis, and E. nietoi, and has wider digital pads than E. dennisi, E. floresvillelai and E. longipes. Unlike E. saxatilis, E. erythrochomus lacks a compact lumbar gland, has shorter/smaller feet, and a smooth skin texture (Palacios-Aguilar and Santos-Bibiano 2020).

COLORATION:

Eleutherodactylus erythrochomus’ coloration in life (from photos and field notes) of both their dorsal surface and limbs are a dark lavender that fades to a light lilac on the ventrolateral surface. The area surrounding the vent is slightly darker. The markings on the dorsum and head are a pale ivory color, with tiny white flecks that scatter on the lateral surface. On the anterolateral side of its head, and the upper lip has a dark sepia marking. The fingers and toes are a neutral gray; however, the digital pads contain a white ring. Lastly, the iris of E. erythrochomus is orange reddish-brown. Some change in color can occur in live individuals with their background color becoming more dark brown, but at rest the individuals become dark lavender again (Palacios-Aguilar and Santos-Bibiano 2020).

When preserved, the coloration, over time, darkened to a dark drown and after more than three years the marking on their dorsal surfaces become indiscernible (Palacios-Aguilar and Santos-Bibiano 2020).

VARIATION:

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

Eleutherodactylus erythrochomus has been located along the south-central Pacific coast of Guerrero, Mexico near the city of Tierra Colorada. Its habitat is characterized by tropical semideciduous forest that grow over large granite boulders. Their habitats contains complex cave systems, crevices, and cliffs (Palacios-Aguilar and Santos-Bibiano 2020).

Life History, Abundance, Activity, and Special Behaviors
Specimens were found between the hours of 1700 - 0100 (Palacios-Aguilar and Santos-Bibiano 2020).

Eleutherodactylus erythrochomus live in sympatry with other amphibians such as Agalychnis dacnicolor, E. pipilans, and Incilius marmoreus. These amphibians are known to live in forests with high temperatures and have morphological characteristics such as expanded digit pads (Palacios-Aguilar and Santos-Bibiano 2020).

Larva
This species is direct-developing (Palacios-Aguilar and Santos-Bibiano 2020).

Trends and Threats
Eleutherodactylus erythrochomus is determined to be highly "Vulnerable" based on restriction of ecological and geographical distribution. The continued threat of deforestation also affects the survival of E. erythrochomus (Palacios-Aguilar and Santos-Bibiano 2020).

Possible reasons for amphibian decline

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

Comments

PHYLOGENETIC RELATIONSHIPS:

Based on Bayesian methods of 16S mtDNA, E. erythrochomus is sister to the clade composed of E. nitidus and E. pipilans. However, these results did not have strong support (Grünwald et al. 2021). Further Bayesian and Maximum Likelihood analyses of 16S, COI, and CytB mtDNA also found E. erythrochomus to be basal to the E. nitidus clade, which includes E. albolabris, E. dilatus, E. maculabialis, E. maurus, E. nebulosus, E. nitidus, E. orarius, E. petersi, E. pipilans, E. rubrimaculatus, E. syristes, and E. sentinelus (Hernández-Austria et al. 2022).

ETYMOLOGY:

The species epithet, “erythrochomus,” is from the Greek words “erythro-”, meaning “red,” and “chόma,” meaning earth in allusion to Tierra Colorada, the city closest to where the species was found (Palacios-Aguilar and Santos-Bibiano 2020).

References

Grünwald, C. I., Reyes-Velasco, J., Franz-Chavez, H., Morales-Flores, K. I., Ahumada-Carrillo, I. T., Rodrıguez, C. M., Jones, J. M. (2021). “Two new species of Eleutherodactylus (Anura: Eleutherodactylidae) from Southern Mexico, with comments on the taxonomy of related species and their advertisement calls.” Amphibian and Reptile Conservation 15, 1–35. [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]

Palacios-Aguilar, R., Santos-Bibiano, R. (2020). “A new species of direct-developing frog of the genus Eleutherodactylus (Anura: Eleutherodactylidae) from the Pacific lowlands of Guerrero, Mexico.” Zootaxa 4750(2), 250-260. [link]

Species Account Citation: AmphibiaWeb 2022 Eleutherodactylus erythrochomus: English: Tierra Colorada Peeping Frog. Spanish: Rana Ladradora de Tierra Colorada <https://amphibiaweb.org/species/9141> University of California, Berkeley, CA, USA. Accessed Apr 24, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Apr 2024.

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