Description
Espadarana callistomma is a large centrolenid frog with an adult male snout-vent length range of 26.7 – 29.6 mm and an adult female snout-vent length range of 30.3 – 31.8 mm. The head is as wide as it is long and the snout is truncate in both the lateral and dorsal views. The dorsolaterally-directed nostrils are closer to the snout than the eye. The indistinct canthus rostralis is straight while the internarial region is slightly depressed. The loreal region is somewhat concave. The large, anterolaterally-directed eyes have horizontal pupils. The almost vertically-oriented tympanum is small, 20–30.8% of eye diameter, and has a transparent, but pigmented, membrane and a conspicuous supratympanic fold that covers the dorsal portion of the tympanic annulus. The lips are somewhat flared (Guayasamin and Trueb 2007).

A humeral spine is visible in males. The unlar has an evident low unlar fold. The palm has a simple elliptical palmar tubercle. The relative finger lengths (using the Shubin and Alberch [1986] method) are IV > V > II ≈ III. There is no webbing between fingers II and III and the webbing formula for for the rest of the fingers is is III2 – 3^1/4IV2^– – 1⁺V. The tips of the fingers expand into nearly round discs, with the transverse diameter of Finger IV being almost half the eye diameter. The pads of the disc are triangular. The fingers have simple, small, round subarticular tubercles and no supernumerary tubercles. When present, the nuptial pads consist of granular ovals that extend from the ventrolateral base of Finger II to the dorsal surface to cover the proximal portion of the finger (Guayasamin and Trueb 2007).

The tibia is slightly longer than half the snout-vent length. There is an evident, low inner tarsal fold but no outer fold. The large inner metatarsal tubercle is ovoid and the indistinct outer metatarsal tubercle is round. No relative toe length was reported, but the webbing formula for the fully webbed feet is I1 – 2^–II0⁺ – 2III1^– – 2^–IV2 – 1V. Like the fingers, the toe discs are round with triangular pads. The disc on Toe IV is narrower than the disc on Finger IV. Also like the fingers, the subarticular tubercles are small and round, and there are no supernumerary tubercles (Guayasamin and Trueb 2007).

The skin of the dorsal and lateral regions of the head and body are shagreen with males having miniscule spinules that are only visible under x100 magnification. The throat is smooth, but the belly and lower flanks are areolate. The posteriorly-directed cloaca opening is located at the upper level of the thighs and is laterally bordered by a fleshy, tuberculate, ∩−shaped fold. The posterior portion of the cloaca has small, fleshy tubercles and from the ventral view, there is a pair of large subcloacal tubercles.

Espadarana callistomma can be differentiated from other genera in Centrolenidae by several features. The white coloration of the ventral parietal peritoneum in E. callistomma differentiates it from the transparent parietal peritoneum in Hyalinobatrachium. The discernible humeral spines in E. callistomma males are not found in Hyalinobatrachium and Cochranella. The large size, uniform green dorsal coloration, and white iris with black reticulations differentiates E. callistomma from members of Centrolene (Guayasamin and Trueb 2007)

Espadarana callistomma appears the most similar to E. prosoblepon, E. andina and Sachatamia ilex. Espadarana callistomma can be distinguished from E. prosoblepon and E. andina by the focal species' large size, uniformly green dorsal coloration without spots, and white iris with black reticulations. Espadarana callistomma can be further differentiated from E. andina by range. From S. ilex, E. callistomma has more pronounced humeral spines in males. There are currently no known characteristics to differentiate females of E. callistomma and S. ilex (Guayasamin and Trueb 2007).

In life, the dorsum is uniformly yellowish-green, typically lacking spots. The upper lip is a whitish-cream color. The eyes have bright white irises with heavy black reticulations. The flanks are white. The anterior two-thirds of the ventral parietal peritoneum, covering the heart, is white while the posterior portion is transparent. The bones are green, and the humeral spine is blue-green. When preserved, the dorsum and limbs are uniformly lavender. The irises are white with dark lavender reticulations. The venter, nuptial pad, and upper lip are cream in color (Guayasamin and Trueb 2007).

Tadpoles in life are brown (Salazar-Nicholls and del Pino 2015).

Humeral spines and spinules on dorsum are absent in females. One female had several small, dark spots on dorsum (Guayasamin and Trueb 2007).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Ecuador

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (1 records).

Espadarana callistomma can be found in the Pacific lowlands of northeastern Ecuador and southern Columbia (77 – 800 m) (Guayasamin et al. 2009, Ospina-Sarria et al. 2010). They occur in the evergreen lowland forests along tributaries of the Río Bogotá, Provincia de Esmeraldas, and Río La Carolina, Provincia de Carchi (Guayasamin and Trueb 2007).

Life History, Abundance, Activity, and Special Behaviors
Espadarana callistomma is primarily active at night (Guayasamin and Trueb 2007).

Males call from atop leaves (Guayasamin and Trueb 2007).

Females lay eggs on tops of leaves along streams (Guayasamin and Trueb 2007). Eggs are darkly pigmented, with a dark brown embryo and pale brown vegetal hemisphere, and are approximately 2.1 mm in diameter. The dark pigmentation may protect the embryo from UV and/or absorb more heat to accelerate development. Clutches contain 32 - 39 eggs. Development time from 32-cell state to hatching is approximately 12 days (Salazar-Nicholls and del Pino 2015).

Trends and Threats
Espadarana callistomma is locally abundant in the localities in which it has been found, though current population trends are unknown. Habitat destruction in the Chocoan ecoregion is a primary threat (Guayasamin 2008).

Possible reasons for amphibian decline

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

Comments
The species authority is: Guayasamin JM, Trueb L. (2007). “A new species of glassfrog (Anura: Centrolenidae) from the lowlands of northwestern Ecuador, with comments on centrolenid osteology.” Zootaxa, 1447:27-45.

Espadarana callistomma was originally described in 2007 (Guayasamin and Trueb) as Centrolene callistommum but was split from Centrolene in 2009 (Guayasamin et al.) based on Bayesian Inference, Maximum Likelihood and Maximum Parsimony analyses on 12S, 16S, ND1, POMC, combined mtDNA, combined nuDNA, and combined datasets. At that time, Espadarana consisted of three known species, E. callistomma, E. prosoblepon and E. andina, and one unknown species. Espadarana callistomma was shown to be sister to E. prosblepon, and the genus Espadarana was sister to the genus Cochranella (Guayasamin et al. 2009).

The genus Espadarana is composed of the Spanish roots “Espada-” meaning “sword”, in reference to the humeral spines in males and in honor the Spanish zoologist Marcos Jiménez de la Espada (who described the first centrolenide frog), and “-rana” meaning “frog” (Guayasamin et al. 2009)

The specific epithet, “callistomma”, is derived from the greek roots “kallistos-” meaning “most beautiful” and “omma-” meaning “eye” (Guayasamin and Trueb 2007).

References

Guayasamin JM, Trueb L. (2007). ''A new species of Glassfrog (Anura: Centrolenidae) from the lowlands of northwestern Ecuador, with comments on centrolenid osteology.'' Zootaxa, 1447, 27-45.

Guayasamin JM. (2008). ''Espadarana callistomma.'' The IUCN Red List of Threatened Species 2008: e.T135738A4195356. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T135738A4195356.en. Downloaded on 15 February 2018.

Guayasamin, J. M., Castroviejo-Fisher, S., Trueb, L., Ayarzaguena, J., Rada, M., Vila, C. (2009). ''Phylogenetic systematics of glassfrogs (Amphibia: Centrolenidae) and their sister taxon Allophryne ruthveni.'' Zootaxa, 2100, 1-97.

Ospina-Sarria JJ, Bolívar-G W, Mendez-Narvaez J. (2010). ''Amphibia, Anura, Centrolenidae, Espadarana callistomma (Guayasamin and Trueb, 2007): First country records from Columbia.'' Check List, 6, 244-245.

Salazar-Nicholls MJ, del Pino EM (2015). ''Early development of the glass frogs Hyalinobatrachium fleischmanni and Espadarana callistomma (Anura: Centrolenidae) from cleavage to tadpole hatching.'' Amphibian and Reptile Conservation, 8, 89-106.

Shubin, N.H., Alberch, P. (1986). ''A morphogenetic approach to the origin and basic organization of the tetrapod limb.'' Evolutionary Biology. Plenum Press, New York, 319–387.

Species Account Citation: AmphibiaWeb 2018 Espadarana callistomma: Beautiful eyes Glassfrog <https://amphibiaweb.org/species/6907> 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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