Calyptocephallela gayi, the Helmeted Water Toad, is a large frog, with adult males growing to 120 mm and the females to 320 mm. This frog has a robust body and a large head with a short round snout. The eyes are small, with vertical pupils and bronze irises. A distinct tympanum is visible. The skin has elongated bumps on the dorsum. Fingers are unwebbed while toes are half-webbed. These frogs are dull brown, with grayish-white bellies. During breeding season, males have nuptial pads on their thumbs
Helmeted Water Toad tadpoles grow very large, to a maximum of 150 mm in length and more than 30 g in weight (Castaneda et al. 2006). The body and foremost part of the tail are grayish brown in color or light green, while the posterior part of the tail is black or dark brown (Diaz and Valencia 1985; Duellman 2003). Labial papillae are present and the mandibles are well-developed, with a tooth formula of 2/3
(Diaz and Valencia 1985). The spiracle is equidistant between the snout and the vent (Diaz and Valencia 1985). The dorsal fin extends over the tail base, with the tail base narrower than half of the maximum body width (Diaz and Valencia 1985). The oral disc is small (narrower than a third of the body width), and there is no anal tube (Diaz and Valencia 1985).
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Chile
Helmeted Water Toads are found in the lowlands of Chile, up to 500 m in elevation (Stuart 2008). They inhabit aquatic environments, such as lakes, rivers and ponds (Duellman 2003). The tadpoles prefer large bodies of lentic water (Diaz and Valencia 1985).
Life History, Abundance, Activity, and Special Behaviors
Calyptocephallela gayi can be active at any time of day. When threatened, this frog becomes aggressive. It will inflate and elevate its body, open its mouth, lunge, and bite potential predators (Duellman 2003).
During the mating season from September through October, males give off a loud "oouu". Amplexus is axillary. After mating, females lay clutches of eggs in shallow water. The clutches consist of one to ten thousand eggs laid in clumps. Hatching occurs in about three weeks (Duellman 2003). The larvae are found in bodies of slow-moving water with muddy bottoms and plentiful vegetation, at depths of at least 1 m (Diaz and Valencia 1985). Calyptocephallela gayi larvae are large, slow swimmers
(Diaz and Valencia 1985). It takes up to two years before they metamorphose into froglets (Diaz and Valencia 1985), with the typical larval period extending from 5-12 months (Castaneda et al 2006) . The froglets measure at least 2.2 cm (Diaz and Valencia 1985).
The adult diet consists of aquatic insect larvae, fishes, frogs, and small birds and mammals (Duellman 2003).
Trends and Threats
Their populations have declined due to hunting as well as loss of habitat (Duellman 2003).
Relation to Humans
Helmeted Water Toads are a food source for some Chileans (Duellman 2003).
Possible reasons for amphibian decline
Drainage of habitat
Local pesticides, fertilizers, and pollutants
Predators (natural or introduced)
Intentional mortality (over-harvesting, pet trade or collecting)
This species was formerly named Caudiverbera caudiverbera but renamed by Myers and Stothers (2006) on finding that the original name was based on a mythical species.
In 2009, Defenders of Wildlife and the Species Survival Network (SSN) recommended that the United States advocate for inclusion of the Helmeted Water Toad (Calyptocephallela gayi, formerly known as Caudiverbera caudiverbera) in Appendix II of CITES (Convention on International Trade in Endangered Species), which would recommend controls on commercial trade in this species. This species is found in Chile and may possibly occur in Argentina, in deep ponds and reservoirs. Threats include harvesting for local consumption, water pollution, and consumption by introduced trout, and pond drainage. Recent trade data for 2005 to 2008 do not specifically indicate the importation of the species into the United States. It is listed as vulnerable by IUCN with a declining population trend. There is no indication that trade is impacting the wild population.
However, the U. S. Fish and Wildlife Service in 2010 decided to not include Calyptocephallela gayi under CITES Appendix II unless "significant additional information is received" about the population and trade status, or assistance is requested by Chile (or Argentina).
This species was featured in News of the Week June 8, 2020:
Fossil frogs have long been expected from Antarctica, holdovers from a Gondwana distribution that must have united proto-South America with proto-Australia/New Zealand/New Guinea. At last they have been found (Mörs et al 2020), in Eocene age rocks from Seymour Island off the east shore of the Antarctic Peninsula. The identity of the frogs, represented by scant remains of an ilium and a fragment of skull roof, is a surprise – Calyptocephalella, a genus represented today by a relatively large, enigmatic single species from the wet temperate zone of Chile. However, the taxon is very old, predating the Cretaceous/Paleocene event, and it has a fossil record in southern South America. The Antarctic fossils were found in a community that included such angiosperms such as water lilies, some marsupials, indicating it was likely a moist, rich environment. Now it is time to find even older Antarctic frogs – they should be there! (Written by David Wake)
Castañeda, L.E., Sabat, P., Gonzalez, S.P., and Nespolo, R.F. (2006). ''Digestive plasticity in tadpoles of the Chilean Giant Frog (Caudiverbera caudiverbera).'' Physiological and Biochemical Zoology, 79, 919-926.
Duellman, W. E. (2003). ''Helmeted water toad, Caudiverbera caudiverbera.'' Grzimek's Animal Life Encyclopedia, Volume 6, Amphibians. 2nd edition. M. Hutchins, W. E. Duellman, and N. Schlager, eds., Gale Group, Farmington Hills, Michigan.
Dunn, E. R. (1931). ''New frogs from Panama and Costa Rica.'' Occasional Papers of the Boston Society of Natural History, 5, 385-401.
Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.
Originally submitted by: Peera Chantasirivisal, Michelle Koo (first posted 2005-11-10)
Edited by: Kellie Whittaker, Michelle S. Koo (2021-11-14)
Species Account Citation: AmphibiaWeb 2021 Calyptocephalella gayi: Helmeted Water Toad <https://amphibiaweb.org/species/2585> University of California, Berkeley, CA, USA. Accessed Sep 24, 2023.
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Citation: AmphibiaWeb. 2023. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Sep 2023.
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