Description
Charadrahyla altipotens is a fairly large frog with a snout-vent length range in males from 68.8 - 75.1 mm and in females from 69.4 - 75.3 mm. The flattened to convex head is narrower than the body. In the dorsal view the moderately long snout tapers to a point, while in the lateral view the snout is rounded and protrudes over the lower jaw. The nostrils are roughly two-thirds of the distance from the tip of the snout to the eyes, slightly protruding, and positioned dorsolaterally. The canthus rostralis is angular. The loreal region is flat. The distinct tympanum is one tympanum diameter distance away from the eye. The heavy supratympanic fold, connecting the posterior corner of the eye to the tympanum and extending towards the arm, partially obscures the upper edge of the tympanum (Duellman 2001).

The arms are moderately long and robust. There is a residual axillary membrane, a thin ventrolateral dermal fold on the forearm, and a distinct transvers dermal fold on the wrist. The short, broad fingers end with large discs. The widest part of the third finger disc is greater than the diameter of the tympanum. There are large, conical, round subarticular tubercles as well as large, more granule-like supernumerary tubercles, although the latter are only found on the proximal segments of the fingers. The fingers are one-half webbed. The prepollex is enlarged and males have nuptial excrescences (Barrio-Amorós et al. 2016), but males do not develop nuptial pads during the breeding season (Duellman 2001).

When extended along the body, the tibiotarsal articulation of the long and slender hindlimbs reaches between the eye and the nostril. When held at right angles to the body, the heels overlap by about half of the length of the shank. The heel has a transverse dermal fold and the tarsus has a strong fold that spans the full length. The inner metatarsal tubercle is elongated, small, and barely visible from above while the outer is small and conical. The toes are also moderately long and slender, ending with discs that are slightly smaller than the fingers, and having large, round, subconical subarticular tubercles. Large, conical supernumerary tubercules are also present as a single row along the proximal segment of each toe. The toes are four-fifths webbed (Duellman 2001)

The skin of the dorsal surface, limbs and ventral shanks is smooth, but the skin is granular on the ventral surface of the thighs and arms as well as on the throat and stomach. The anal opening is located at the midlevel of the thighs and directed posteroventrally. The anal sheath is long and tubular (Duellman 2001).

For C. altipotens tadpoles, the body length at stage 25 is approximately 13.8 mm and the total length is around 41.1 mm. The wide body is slightly depressed. In the dorsal view the snout is bluntly rounded and in the lateral view the snout is truncated. The slightly protuberant nostrils are located halfway between the nostrils and eyes. The small eyes are directed dorsolaterally. The mouth is small and ventral with moderately deep lateral folds on the lips. The mouth has two to three complete borders of small papillae with additional papillae in the lateral fold. There are two equally long upper tooth rows that extend to the edges of the lip. The second upper tooth row is medially interrupted. There are three complete lower tooth rows that are approximately equal in length and all shorter then the upper tooth rows. The upper beak is robust, broadly arched, and has a slender lateral process, while the lower beak is broadly V-shaped. The spiracle is sinistral with the spiracular opening located below the midline about two-thirds the distance the length of the body. The dextral anal tube is moderately long. The tail is long with moderately robust caudal musculature that is deeper than either fin at the midlength. The dorsal fin barely extends onto the body and both caudal fins are low and rounded at the end. At metamorphosis the snout-vent lengths range is 17.5 - 19.7 mm (Duellman 2001).

Charadrahyla altipotens is similar to C. taeniopus, C. chaneque, and Exerodonta pinorum but can be distinguished from all of them by a narrower head and longer legs. More specifically, C. altipotens has a smaller head, pointed snout in both males and females, and longer legs than C. taeniopus. Also, the ventral coloration in C. taeniopus is white or brown instead of yellow and it does not have a canthal stripe, but does have tiny vocal sacs. From C. chaneque, C. altipotens can be differentiated by C. chaneque having tubercles on the dorsal surface, a blunt snout, and a tympanum with a diameter less than half the eye diameter. It may be hard to distinguish juvenile C. altipotens and E. pinorum, but E. pinorum juveniles have a smaller tympanum diameter, a short snout, as well as less webbing on the hands (Duellman 2001). Charadrahyla altipotens can also be differentiated from C. tecuani and C. trux by the focal species lacking hypertrophied webbing. Having a pointed snout differentiates C. altipotens from C. nephila. From C. esperancensis, C. altipotens can be differentiated by lacking a rostral keel (Barrio-Amorós et al. 2016).

In life, the dorsal background coloration of C. altipotens ranges from tan to pale green or dark olive green but can shift to dark brown (Duellman 2001, Barrio-Amorós et al. 2016). The dorsum may have darker green or brown spots and transverse bars on the dorsal surfaces of the limbs. A narrow, tan labial strip is present. There are two parallel canthal stripes that stretch from the snout, along the canthus rostralis, towards the upper part of the eye and may extend along the supratympanic ridge to the insertion of the arm. The upper stripe is pale greenish-bronze to yellow and the lower is dark brown. The flanks and anterior surface of thighs have a bright creamy yellow background with dark brown reticulations and spots. The posterior portion of the thighs, the ventral surface of the hands, and the webbing of the feet are all yellowish tan. The fingers have a tan background color with the third and fourth fingers and the fourth and fifth toes having transverse brown bars while the other digits had brown flecks. Along the ventrolateral edge of the forearms, along the outer edge of the foot, and above the anus are cream-colored stripes. The ventral color is creamy yellow with the throat, and chest being brighter. The iris is copper colored on the periphery and bronze in the middle with black reticulations. The pupil is horizontally elliptical and has a ventral notch. The palpebal membrane is transparent in the upper portion and pale bluish-green with brown reticulations on the lower portion (Duellman 2001). The nuptial excrescences are dark grey (Barrio-Amorós et al. 2016)

In preservative, the coloration of the dorsal side of C. altipotens is pale brown with darker brown spots on the back as well as dark brown transverse bands on the forelimbs and hindlimbs. The flanks and anterior thighs fade to creamy white with dark brown spots and brown reticulations respectively. The canthal stripe fades to tan. The ventral surface of the feet become brown while the rest of the ventrum is creamy white (Duellman 2001).

In life, tadpoles have dark brown or black bodies with small golden flecks on the sides and belly. The caudal musculature is dorsally black, laterally brown, and ventrally darker brown with brown flecks on the fins. The iris is pale gold. In preservative, the gold flecks disappear, the tail musculature fades to creamy tan and the body is dorsally dark brown (Duellman 2001).

In life, subadults are pale reddish tan on their dorsal surfaces with darker reddish-brown bars on the limbs and blotches on their dorsum. Their canthal strip is yellowish-tan and some individuals have dark brown middorsal strips. The brown reticulations on the anterior surface of the thighs may extend onto the ventrum and brown flecks may be present on the ventral side of the shanks (Duellman 2001). Males differ from the females by having shorter legs and smaller tympanums (Duellman 2001).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

Charadrahyla altipotens is distributed on the Pacific Slopes of the Sierra Madre del Sur in Oaxaca, Mexico from an elevation range of 1100 - 1900 m in cloud forests and pine-oak forests. The individuals are found near streams, no more than 120 cm away. Adults were found on the ground, rocks, and branches, while juveniles were found on leaves at night. Individuals were also found up to heights of 120 cm above the ground (Duellman 2001).

Life History, Abundance, Activity, and Special Behaviors
Charadrahyla altipotens breed during the dry season at which time adults and juveniles are found in trees and bushes near streams in cloud and pine-oak forests. The females lay eggs in rocky streams and pools. Tadpoles metamorphosis in the rainy season (Duellman 2001).

Males have enlarged testes, and it is hypothesized that an increase size of testes is correlated to the large production of sperm (Duellman 2001).

Charadrahyla altipotens do not have vocal slits or a vocal sac, which suggest that this species lacks a voice and is not able to participate in mating calls (Duellman 2001).

The species is able to change coloration (Duellman 2001, Barrio-Amors et al. 2016)

Trends and Threats
Charadrahyla altipotens has a decreasing population trend and has a listing by the Mexican government as a species under special protection and by the IUCN Red List as “Critically Endangered” (Barrio-Amors et al. 2016). The major threats to the species are residential and commercial development from human population growth, invasive non-native diseases, and biological resource use such as logging and wood harvesting (Santos-Barrera and Canseco-Márquez 2004).

In 2016, Barrio-Amors et al. were able to find the species in various life stages at three different localities, which gave them some optimism about the species’ survival. However, they noted that because of the fragmentation and loss of cloud forest habitat, the species should remain “Critically Endangered” and have a raised threat national threat status to “Threatened”. More fieldwork is needed to learn more about the habitat requirements of the species.

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Urbanization
Local pesticides, fertilizers, and pollutants
Disease

Comments
The species authority is: Duellman, W. E. (1968). “Descriptions of new hylid frogs from Mexico and Central America.” University of Kansas Publications. Museum of Natural History 17: 559–578.

At the time of the genus description, Charadrahyla, was composed of five species: C. altipotens, C. chaneque, C. nephila, C. taeniopus, and C. trux; this was determined by 56 transformation in the ribosomal genes as well as the nuclear and mitochondrial proteins. The genus Megastomatohyla is closely related to Charadrahyla (Faivovich 2005). By 2019, three more species were described, C. tecuani by Campbell et al. (2009), C. esperancensis by Canseco-Márquez et al. (2017), and C. sakbah by Jiménez-Arcos et al. (2019). Genetic analysis is needed to reveal the relationships within the genus.

The genus, Charadrahyla, was named in 2005 by Faivovich et al. The name is derived from the Greek word for “ravine”, “charadra”, in reference to where the frogs in this genus are found.

The species epithet, “altipons” means “mighty”, and it is used in reference to fertilization by the production of large quantities of sperm in the testes. (Duellman 2001).

References

Barrio-AmorósBarrio-Amorósb (2016). ''Charadrahyla altipotens (Anura: Hylidae), a Critically Endangered treefrog rediscovered in Oaxaca, Mexico.'' Mesoamerican Herpetology, 3(3), 787−790. [link]

Campbell, J. A., Blancas-Hernández, J. C., Smith, E. N. (2009). ''A new species of stream-breeding treefrog of the genus Charadrahyla (Hylidae) from the Sierra Madre del Sur of Guerrero, Mexico.'' Copeia, 2009(2), 287-295. [link]

Canseco-Márquez, L., Ramírez-González, C.G., González-Bernal, E. (2017). ''Discovery of another new species of Charadrahyla Anura, Hylidae) from the cloud forest of northern Oaxaca, México.'' Zootaxa, 4329(1), 64-72. [link]

Duellman, W. E. (2001). The Hylid Frogs of Middle America. Society for the Study of Amphibians and Reptiles, Ithaca, New York.

Faivovich, J., Haddad, C. F. B., Garcia, P. C. A., Frost, D. R., Campbell, J. A., Wheeler, W. C. (2005). ''Systematic review of the frog family Hylidae, with special reference to Hylinae: phylogenetic analysis and taxonomic revision.'' Bulletin of the American Museum of Natural History, (294), 1-240. [link]

Jiménez-Arcos, V.H., Calzada-Arciniega, R.A., Alfaro-Juantorena, L.A., Vázquez-Reyes, L.D., Blair, C., Parra-Olea, G. (2019). ''A new species of Charadrahyla (Anura: Hylidae) from the cloud forest of western Oaxaca, Mexico.'' Zootaxa, 4554(2), 372-385. [link]

Santos-Barrera, G., Canseco-Márquez, L. (2004). “Charadrahyla altipotens.” The IUCN Red List of Threatened Species 2004: e.T55384A11288683. http://dx.doi.org/10.2305/IUCN.UK.2004.RLTS.T55384A11288683.en. Downloaded on 17 May 2019. https://www.iucnredlist.org/species/55384/11288683

Species Account Citation: AmphibiaWeb 2019 Charadrahyla altipotens: Yellowbelly Voiceless Treefrog <https://amphibiaweb.org/species/708> University of California, Berkeley, CA, USA. Accessed Nov 27, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 27 Nov 2024.

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