Challhuaco frog (Atelognathus nitoi)

Challhuaco frog
Loading more images and videos...

Challhuaco frog fact file

Challhuaco frog description

GenusAtelognathus (1)

Discovered as recently as 1973, the little-known Challhuaco frog can be distinguished by its stout body, the upperside of which is coloured brownish or greyish, and marked with irregular dark spots. The skin is loose and baggy on the sides, but smooth on the back and on the unmarked, whitish belly (2).

Rana Del Challhuaco.
Length: 45 mm (2)

Challhuaco frog biology

Mostly found on land, the adult Challhuaco frog is well camouflaged amongst the fallen leaves and branches that carpet the floor of its forest habitat. Breeding takes place in spring (mid to late October), with the females spawning in Laguna Verde, and also, during particularly rainy years, in temporary water bodies formed after the snowmelt. After hatching, the tadpoles swim to the shallow water around the shore of the lake. Here they grow from just under a centimetre to over seven centimetres in length, and begin to explore the lake. The tadpoles feed on microscopic animals and algae suspended in the water on the lakebed. In Laguna Verde, the tadpoles metamorphose either at the end of summer (December), or remain as tadpoles throughout the winter, metamorphosing in the following summer. This means that the offspring from a single spawn can contribute to the Challhuaco frog population two years in a row, a useful survival strategy if the conditions in one year are particularly adverse. For those tadpoles found in temporary water bodies, deferring development is not possible, as they must metamorphose quickly, before their habitat dries up at the end of summer. In the period following metamorphosis, the juvenile frogs remain near the lake’s shore, but as they mature they move into the forest (2).


Challhuaco frog range

Endemic to Argentina, the Challhuaco frog is restricted to the area surrounding Laguna Verde, a small mountain lake in the Nahuel Huapi National Reserve in north-west Patagonia (2).


Challhuaco frog habitat

The adult challhuaco frog inhabits humid areas within the high-altitude, deciduous mountain forest surrounding Laguna Verde. The lake is found at 1,550 metres above sea level, and is only 80 metres wide and 5 to 6 metres deep. Annual temperatures average between five and eight degrees Celsius, dropping below zero in the winter, when the surface of the lake freezes and ground is covered with snow up to one metre deep. (2)


Challhuaco frog status

Classified as Vulnerable (VU) on the IUCN Red List (1).

IUCN Red List species status – Vulnerable


Challhuaco frog threats

Despite being relatively common within its range, the Challhuaco frog occupies such a tiny area that its population is only estimated to be around 1,000 individuals. It is, therefore, extremely vulnerable to disturbance, and even a small-scale adverse event could cause this species’ extinction. While, the Challhuaco frog’s habitat is relatively remote, the presence of a nearby mountain lodge means that human disturbance due to firewood collection and fuelwood gathering could be problematic. The Challhuaco frog is also at risk from forest fires, and from the worldwide increase in ultraviolet radiation—thought to be due to decreases in atmospheric ozone, climate warming and lake acidification—which is proving detrimental to other amphibian species (2) (3).


Challhuaco frog conservation

The entire known population of the Challhuaco frog is located in the reserve area of the Parque Nacional Nahuel Huapi (1), the largest and oldest National Park in South America (4). Having been made aware of this species’ precarious position, the National Park Administration has implemented a ban on the removal of logs from certain areas, as well as the construction of a new trail to the mountain lodge that avoids temporary water sources that the frog inhabits (2). Despite these controls, the ever-present risk of fire and the threat of increased ultraviolet radiation, mean that the Challhuaco frog population must be closely monitored, ensuring that in the event of a decline, conservation measures can quickly be employed (1) (2).

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

To learn more about the worldwide decline of amphibians and what can be done to stop it, visit:



This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:


A cold-blooded vertebrate of the class Amphibia, such as a frog or salamander, which characteristically hatches as an aquatic larva with gills. The larva then transforms into an adult with air-breathing lungs.
A plant that sheds its leaves at the end of the growing season.
A species or taxonomic group that is only found in one particular country or geographic area.
Referring to the process metamorphosis, an abrupt physical change from the larval to the adult form.
An abrupt physical change from the larval to the adult form.


  1. IUCN Red List (January, 2009)
  2. Úbeda, C., Zagarese, H., Diaz, M. and Pedrozo, F. (1999) First steps towards the conservation of the microendemic Patagonian frog. Atelognathus nitoi. Oryx, 33: 59 - 66.
  3. AmphibiaWeb (January, 2009)
  4. McCloskey, E. and Burford, T. (2006) Argentina: The Bradt Travel Guide. Bradt Travel Guides, Chalfont St. Peter.

Image credit

Challhuaco frog  
Challhuaco frog

© Richard Sage

Richard Sage


Link to this photo

Arkive species - Challhuaco frog (Atelognathus nitoi) Embed this Arkive thumbnail link ("portlet") by copying and pasting the code below.

Terms of Use - The displayed portlet may be used as a link from your website to Arkive's online content for private, scientific, conservation or educational purposes only. It may NOT be used within Apps.

Read more about



MyARKive offers the scrapbook feature to signed-up members, allowing you to organize your favourite Arkive images and videos and share them with friends.

Play the Team WILD game:

Team WILD, an elite squadron of science superheroes, needs your help! Your mission: protect and conserve the planet’s species and habitats from destruction.

Conservation in Action

Which species are on the road to recovery? Find out now »

Help us share the wonders of the natural world. Donate today!


Back To Top