Chaltenobatrachus grandisonae (Lynch, 1975)
Puerto Eden Frog
The six Chaltenobatrachus grandisonae tadpole species examined were between stages 31 and 39. With an elliptical build, the examined tadpoles had a mean length of 49.25±1.72 mm. The skin is transparent, making the chondrocranium, gills, and heart all visible. The body, which is somewhat indented, is 2 times longer than tall and 1.2 times wider than tall. The posterior region of the head exhibits slight constriction. The oral disc is located towards the lower end of the head. It displays a single row of emarginated papillae, with a very large rostral gap. Supra-angular, angular, and infra-angular intra-marginal lateral papillae are all present and sharp pointed. The intra-marginal papillae are absent. The labial teeth are well developed and keratinized with a 2(2)/3(1) tooth row-formula. The P1 gap is very narrow. The upper and lower jaw sheaths are well developed. They are wider than high, with fine serrate margins. The lower jaw sheath is strongly curved. The snout is rounded and nostrils are small and circular with an elevated internal rim. The nostril is slightly closer to the snout than to the eyes, with the distance between the nostrils 0.4 to 0.6 times smaller than the distance between the eyes. The large eyes, oriented dorsolaterally, are positioned lateral with a visible, yet small umbraculum. The spiracular tube is present and is situated on the far-left side, free from the body wall. The spiracle is located in posterolateral region, beneath the mid-line of the body. The ventral tube is short and located on the dextral side. The tail, which is marginally taller than the body, accounts for about 60 to 65% of the tadpole’s total length. The caudal musculature is robust, and does not quite reach the tip of tail. The dorsal and ventral fins are well developed, of comparable height, and exhibit lightly arched margins. The dorsal fin arises from either the last part of the body or at the tail-body junction. The ventral fin arises at the cloacal opening. The tip of the caudal fin is rounded (Basso et al. 2011).
At the time of its description, Chaltenobatrachus grandisonae was the only member of its genus and was most closely related to frogs of the genus Atelognathus. The placement of C. grandisonae in a new genus is mostly obvious by differences from the defining features of the Atelognathus frogs. The genus Atelognathus frogs exhibit large, exposed frontoparietal fontanelle, short palatine bones, and large nasal opening while Chaltenobatrachus has more extensive frontoparietals, long palatines, and small nasal openings. They are further differentiated by C. grandisonae’s extensive alary processes of the premaxillae, maxillary teeth extending up to the middle of the orbit, well ossified sphenethmoid, anteriorly dilated omosternum, webbed fingers, and coloration. Chaltenobatrachus grandisonae has a uniform bright green dorsal coloration with brown to reddish warts and an orange iris with gold spots (Basso et al. 2011).
Features that differentiate C. grandisonae tadpoles from Atelognathus tadpoles are that the former have transparent skin and papillae that protrude laterally from the oral disc in the dorsal view (Basso et al. 2011).
In life, Chaltenobatrachus grandisonae exhibits a uniform bright green dorsal coloration with brown to slightly red warts. Dark bands extend across the dorsal side of the legs. Dorsal streaking and warts are more evident in juveniles. Juveniles also exhibit more intense coloring. The belly and lower part of the flanks are greyish with scattered tiny black spots. The throat is white with small dark spots. The ventral skin of the legs is brown and translucent. A dark brown band stretches from the tip of the snout along to axillary region to the supratympanic fold, including the nostril. A dark patch reaches from under the eye to the upper lip. The eyes are circular, with an orange iris that has gold spots and a dark vertical line under the pupil. In some specimens, a small and rounded ventral pupillary nodule is found on the lower border of the iris (Basso et al. 2011).
In life, the tadpoles are dark brown with golden spots. The body has a translucent contour, due to its ventral and lateral skin being transparent. The ventral side of the head is unpigmented and the abdomen is spotted with a few groups of golden, superficial guanophores. The caudal musculature is dark brown with asymmetrical golden patches. The fins are translucent with scattered melanophores and guanophores. The iris is gold, with black spots. The nostrils have a pigmented rim. The spiracular tube is transparent. The keratinized buccal structures are highly pigmented (Basso et al. 2011).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Argentina, Chile
Life History, Abundance, Activity, and Special Behaviors
Chaltenobatrachus grandisonae have been found living sympatrically with Eupsophus coppingeri and Nannophryne variegata at the Wellington Island locality (Basso et al. 2011).
Chaltenobatrachus grandisonae tadpoles can be found in many different localities, all of which are in water. They have been found in small to larger pools of 3 - 20 meters in diameter and 0.1 - 1.0 m deep with a pH around 6.5. They can also be found in bogs and wetlands. The tadpoles co-inhabit these bodies of water with macrophytes, liverworts, Gunnera magellanica, and spherical Nostoc colonies. At the Lago del Desierto locality, C. grandisonae tadpoles were found cohabitating shallow pools with Nannophryne variegata tadpoles (Basso et al. 2011).
Larval development is aquatic and the larvae are known to be active feeders. Metamorphosis takes place at the end of summer. In the beginning of summer tadpoles of different life stages were found living together. This suggests that these tadpoles developed from clutches laid in different years, and that these tadpoles have prolonged aquatic development over the winter (Basso et al. 2001).
Plants found in C. grandisonae habitat include site-specific bryophytes, pteridophytes, Nothofagus antarctica that create a dense mat on the forest floor, Nothofagus pumilio, and austral beeches that rise above the shrubs (Basso et al. 2011, Díaz-Páez et al. 2015).
Trends and Threats
Samples for DNA amplification were collected from liver or muscle tissue. A DNA dataset of 3108 base pairs from 12S, 16S, cytb, and rhod sequencing developed a single most parsimonious tree that revealed that C. grandisonae is a distinct genus and is sister to the genus Atelognathus. The genera Chaltenobatrachus and Atelognathus share a common ancestor with the genera Hylorina and Batrachyla. The subfamily, Batrachylinae encompasses the genera Chaltenobatrachus, Atelognathus, Hylorina, and Batrachyla (Basso et al. 2011).
The genus Chaltenobatrachus is derived from Chaltén, the native name of the mountain located near where the frog was found. The common name Puerto Eden Frog comes from the first location that it was found (Basso et al. 2011). There is no officially published etymology for the species epithet “grandisonae”. However, the epithet “grandisonae” is presumably from Alice G. C. Grandison, a colleague of John D. Lynch (Lynch 1975).
Chaltenobatrachus grandisonae is synonymous with Atelognathus grandisonae and Telmatobius grandisonae (Veloso and Núñez 2010).
Chaltenobatrachus grandisonae is the founding species in its genus (Basso et al. 2011).
Basso, N.G., Úbeda, C.A., Bunge, M.M., Martinazzo, L.B. (2011). ''A new genus of neobatrachian frog from southern Patagonian forests, Argentina and Chile.'' Zootaxa, 3002, 31-44.
Díaz-Páez, H., Alveal, N., Cisternas-Medina, I., Ortiz, J.C. (2015). ''New distribution records of Chaltenobatrachus grandisonae (Anura: Batrachylidae) in Patagonia, Chile.'' Check List, 11(4), 1668.
Lynch, J.D. (1975). ''A new chilean frog of the extra-Andean assemblage of Telmatobius (Amphibia: Leptodactylidae).'' Southern California Academy of Sciences Bulletin, 74(3), 160-161.
Veloso, A., Núñez. H. (2010). Chaltenobatrachus grandisonae. The IUCN Red List of Threatened Species 2010: e.T2295A9402009. http://dx.doi.org/10.2305/IUCN.UK.2010-2.RLTS.T2295A9402009.en. Downloaded on 15 November 2016.
Originally submitted by: Darren Ayoub (first posted 2016-12-19)
Edited by: Ann T. Chang (2016-12-19)
Species Account Citation: AmphibiaWeb 2016 Chaltenobatrachus grandisonae: Puerto Eden Frog <https://amphibiaweb.org/species/2564> University of California, Berkeley, CA, USA. Accessed Jun 2, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 2 Jun 2023.
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