AmphibiaWeb - Atelopus epikeisthos


(Translations may not be accurate.)

Atelopus epikeisthos Lötters, Schulte & Duellman, 2005
family: Bufonidae
genus: Atelopus
Species Description: Loetters S, Schulte R, Duellman WE (2004) A new and critically endangered species of Atelopus from the Andes of northern Peru (Anura: Bufornidae). Rev. Esp. Herp. 18:102-109
Atelopus epikeisthos
© 2017 Willy L. Delgado (1 of 12)
Conservation Status (definitions)
IUCN Red List Status Account Endangered (EN)
National Status None
Regional Status None


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Atelopus epikeisthos is a Peruvian harlequin frog described from one male with a snout-vent length of 38.2 mm (Lötters et al. 2004). In 2017, a female with a snout-vent length of 68.4 mm was found (Santa-Cruz et al.). The head is slightly longer than it is wide. The head length and width are almost a third of the snout-vent length. Vertebral neural processes are not very visible. The snout tapes to a point. The snout tip is rounded from the dorsal view. In lateral view, the profile of the snout tip to the anterior margin of the jaw protrudes. There is a swollen gland on the tip of the snout. The nostrils do not protrude and they are just behind the level of the lower jaw’s apex. It has a distinct canthus rostralis that is slightly convex and swollen from the tip of the snout to the nostril, straight from the nostril to the eye. It has a concave loreal region. The upper lip is not flared. The interorbital region and the posterior region of the head are smooth and flat. It has a glandular postorbital crest. It lacks a tympanic membrane and appears to lack a tympanic annulus and stapes. The gular region lacks warts, spiculae, and coni. The forearm is less than a third of the snout-vent length and it is fairly short and robust. Proximally, the forearm is nearly twice as thick as it is distally. The metacarpal tubercles are defined. There are many supernumerary tubercles. Fingers III - IV have subarticular tubercles. The digital tips are not expanded. The thumb is more than half the length of the hand. The phalangeal formula is 2 - 2 - 3 - 3. It lacks webbing between fingers. Round, flattened warts with a diameter around 1 - 2 mm are scattered on the dorsal surfaces. These warts are denser at the body’s periphery and extremities. The sides of the head, behind the jaw angle, and the postorbital crest all lack warts. The ventral surfaces are wrinkly and lack warts, spiculae, and coni (Lӧtters et al. 2004).

Atelopus epikeisthos is most similar in appearance to A. angelito, but can be differentiated because A. epikeisthos is larger. Atelopus epikeisthos has pale yellowish tan outer matecarpal and metatarsal tubercles that are surrounded by darker color, which distinguishes it from A. angelito, A. dimorphus, A. eusebianus, A. andinus, A. pachydermus, A. pulcher, A. seminiferus, A. muisca, and A. bomolochos. Atelopus epikeisthos can be distinguished from A. dimorphus because A. epikeisthos has the phalangeal formula of 2 - 2 - 3 - 3 while A. dimorphus has the phalangeal formula of 1 - 2 - 3 - 3. Additionally, A. dimorphus has a longer tibia than foot while A. epikeisthos has a longer foot than tibia. Atelopus epikeisthos is different from A. eusebianus, A. muisca, and A. exiguus because A. epikeisthos is larger and lacks spiculae. Atelopus epikeisthos can be distinguished from A. andinus and A. seminiferus because A. epikeisthos is larger, has a uniform olive-green dorsum, and has warts on the dorsum but lacks spiculae. Atelopus epikeisthos differs from A. pachydermus because A. epikeisthos is smaller and has uniform olive-green dorsal surfaces. Atelopus epikeisthos can be differentiated from A. pulcher because A. epikeisthos has dorsal warts, a uniform olive-green dorsum. Atelopus epikeisthos also lacks A. pulcher’s reddish central surfaces including its palms and soles. Atelopus epikeisthos is different from A. bomolochos and A. peruensis because A. epikeisthos lacks spiculae (Lӧtters et al. 2004). Atelopus epikeisthos can be differentiated from A. pyrodactylus because A. epikeisthos has a more robust body, inconspicuous vertebral neural processes, lacks warts on the gular region and lacks coni in the dorsolateral region and flanks. Atelopus epikeisthos can be further differentiated by its green dorsum lacking tan vermiculation, and its mainly yellowish-tan venter (Venegas and Barrio 2005).

In life, A. epikeisthos has a bright olive-green dorsum and yellow-tan venter. The outer metacarpal and metatarsal tubercles are yellowish-tan and a darker color surrounds it. The chest is whitish-tan. The posterior venter and the inner palm and sole are all red-orange. There is a golden ring around the pupil (Lӧtters et al. 2004).

In preservative, the dorsum is a dull olive-green. Anterior to the arm insertion and toward the flanks, it is paler. The ventral surfaces, including palmar and plantar surfaces are cream. Finger I and Toes I - II are cream. There are some black markings on every finger and toe, outer edges of the palms and soles, metacarpus and metatarsus, proximal parts of feet, on the knees, and around the cloacal opening. The outer metacarpal and metatarsal tubercles are pale cream. (Lӧtters et al. 2004).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Peru

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The type locality of A. epikeisthos is the eastern part of the Cordillera Central in northern Peru. The type locality is described a small ravine near the road that travels from Chachapoyas to Molinopampa. The ravine has some remaining humid montane forest. There is tree fern vegetation (Lotters et al. 2004). Atelopus epikeisthos was also found in leaf litter of a montane forest close to Shipasbamba, Bongara Province, Amazonas Region, Peru (Santa-Cruz et al. 2017). Atelopus epikeisthos occurs between 1,733 and 2,010 m asl. The two localities of A. epikeisthos are 60 km apart and the species could occur between them. The known range’s extent of occurrence is 233 km2 (IUCN 2018).

Life History, Abundance, Activity, and Special Behaviors

Atelopus epikeisthos has displayed the “Unken reflex” when picked up (Lotters et al. 2004).

Trends and Threats

The population is decreasing (IUCN 2018). The species is threatened by habitat destruction. In 2002, the type locality of A. epikeisthos was cleared for cattle pasture and corn fields (Lotters et al. 2004). Forest fires and agricultural activities in the Shipasbamba locality also threaten A. epikeisthos. Additionally, it is probable that existing subpopulations could be susceptible to the chytrid fungus that has resulted in the decline of closely related species (IUCN 2018).


Maximum likelihood, Maximum Parsimony, and Bayesian analyses on mitochondrial fragments of cyt b and COI found that A. epikeisthos is most closely related to A. peruensis, and these two species are sister to A. bomolochos, which altogether are sister to A. nanay. These four species form the clade of species from the High Andes of Ecuador and Peru. This clade is sister to the clade containing A. pulcher, A. flavescens, A. cf. hoogmoedi, and A. cf. spumarius (Ramirez et al. 2020).

The species epithet, “epikeisthos” is a Greek adjective that means “threatened through adverse circumstances” in reference to its conservation status (Lӧtters et al. 2004).


IUCN SSC Amphibian Specialist Group (2018). Atelopus epikeisthos. The IUCN Red List of Threatened Species 2018: e.T136162A89221263. Downloaded on 02 July 2021.

Lӧtters, S., Rainer, S., Duellman, W. E. (2004). “A new and critically endangered species of Atelopus from the Andes of northern Peru (Anura: Bufonidae).” Revista Española de Herpetología 18:101-109.

Ramírez, J. P., Jaramillo, C. A., Lindquist, E. D., Crawford, A. J., & Ibáñez, R. (2020). “Recent and Rapid Radiation of the Highly Endangered Harlequin Frogs (Atelopus) into Central America Inferred from Mitochondrial DNA Sequences.” Diversity (14242818), 12(9), 360.

Santa-Cruz, R., Delgado, W. L., Medina, C. E., Treviño, I., Von May, R. (2017). “Distribution and conservation status of the critically endangered harlequin frog Atelopus epikeisthos (Anura: Bufonidae).” Salamandra 53(3): 423-425.

Venegas, P. J., Barrio, J. (2005). “A new species of harlequin frog (Anura: Bufonidae: Atelopus) from the northern Cordillera Central, Peru.” Asociación Herpetológica Española, 19: 103-112.

Originally submitted by: Kira Wiesinger (2021-07-27)
Description by: Kira Wiesinger (updated 2021-07-27)
Distribution by: Kira Wiesinger (updated 2021-07-27)
Life history by: Kira Wiesinger (updated 2021-07-27)
Trends and threats by: Kira Wiesinger (updated 2021-07-27)
Comments by: Kira Wiesinger (updated 2021-07-27)

Edited by: Ann T. Chang (2021-07-27)

Species Account Citation: AmphibiaWeb 2021 Atelopus epikeisthos <> University of California, Berkeley, CA, USA. Accessed Jul 19, 2024.

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Citation: AmphibiaWeb. 2024. <> University of California, Berkeley, CA, USA. Accessed 19 Jul 2024.

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