Somuncura Frog
(Somuncuria somuncurensis)
This is a little-known frog, inhabiting the thermal springs and streams of Patagonia’s Somuncura plateau. Being permanently aquatic within these warm waters, it has a near-constant body temperature of 20-22°C, which is unusual for an amphibian. The Somuncura frog is generally quite rare and is thought to be declining within its small area of occupancy. Its range is within the Somuncura Provincial Reserve, although it is still threatened by introduced predatory fish, the canalisation of spring water towards local towns and villages for domestic use, and the impacts of livestock farming, which include overgrazing and chemical pollution of waterways from sheep dips.
Urgent Conservation Actions
Further survey work to establish the current population status; development of a Conservation Action Plan; habitat protection, including restoration of native vegetation.
the Rio Negro Province of Argentinean Patagonia
The common, generic and species name of the Somuncura frog (Somuncuria somuncurensis) is derived from the name of the isolated Patagonian plateau on which this frog lives: Argentina’s Somuncura Plateau.
Evolutionary Distinctiveness
Order: Anura
Family: Leiuperidae
Formerly placed in a subfamily of the Leptodactylidae (the “Leptodactylid frogs”) called the Telmatobiinae, the Somuncura frog is the only species within its genus (also described as a “monotypic species”). This species is now placed in the newly assembled Leiuperidae family, which contains 76 species. As a group, the Leptodactylidae has been reorganised recently and split into a number of different families, including the Leiuperidae. It is now thought that the redefined Leptodactylidae diverged from all other amphibain groups about 60 million years ago, five milllion years after the extinction of the dinosaurs. However, it seems the Leiuperidae split from the Leptodactylid frogs 45 million years ago and started to evolve independently from all other modern amphibians. They are more different from their closest relatives as monkeys are from humans – in fact, five million years of evolution more different!

The Somuncura frog is especially distinct because it is a monotypoc species. Permanently aquatic, it makes use of thermal streams to stay at a constant temperature of 20-22°C, which is unusual for a amphibian because most species have body temperatures that fluctuate widely with their environment. The Somuncura frog lives at unusually stable temperatures for a non-tropical species because of the thermal streams and springs it inhabits.
Somuncura frog is a slender, medium sized frog, with adult females reaching a total length of around 38 mm. The head is fairly small with large protruding eyes that are golden in colour. This species has long slender fingers and toes, the toes being about one-third webbed. The Somuncura frog has unusual eyes, with two symmetrical rounded structures on the centre of the upper and lower border of the iris (the pigmented part of the eye which surrounds the pupil). The skin is smooth, with the colouration being bright yellowish-brown on the upper surfaces of the head, body and legs. Irregular dark spots are present across the back, and wavy dark reticulated lines pattern the sides ofthe body and backs of the thighs. A characteristic yellowish stripe runs centrally down the top of the head and half of the back. The belly is purplish-yellow in colour with dark grey reticulated spots. The lower surface of the thighs is purplish-rose, with faint grey reticulated spots.
The Somuncura frog is a wholly aquatic species, inhabiting and breeding in permanent thermal springs and streams originating in the northern slopes of Patagonia’s Somuncura Plateau. This species lives under stones in the current of the streams, or is submerged in soft masses of floating mosses. Not much is known about this species, although it probably breeds by laying eggs in fairly protected areas of the thermal springs and streams it inhabits. These are likely to develop fairly quickly in the warm waters, hatching into tadpoles which, in turn, metamorphose before long into froglets. The diet is likely to comprise aquatic invertebrates, although further study is required to elucidate other aspects of the life history of this species.

Body temperatures of active amphibians can range between -2° and 35.7°C, and there is generally much variation in these temperatures throughout the day and night, as well as across the seasons. The temperature of an amphibian therefore often reflects that of the environment. Constant body temperatures in amphibians are only possible if the prevailing environmental conditions do not vary. Therefore, the body temperature of the Somuncura frog is limited to a nearly constant temperature of 20-22°C, matching the thermal springs in which it lives.
The habitat of the Somuncura frog comprises thermal springs and streams originating in the northern slopes of Somuncura Plateau. It is not present in modified habitats.
This species is known only from the Somuncura Plateau, an isolated basaltic plateau in the Rio Negro Province of Argentinean Patagonia. It has an altitudinal range of 500-700 metres above sea level.
Population Estimate
No accurate population estimates exist for the Somuncura frog, although it is generally quite rare and is thought to be declining.
Population Trend
This species is thought to be in decline by the IUCN Red List of Threatened Species.
The Somuncura frog is listed as Critically Endangered in the IUCN Red List of Threatened Species because its area of occupancy is less than 10 km sq., its distribution is severely fragmented, there is continuing decline in the extent and quality of its aquatic habitat, and a decline in the number of subpopulations, on the Somuncura Plateau, Argentina.
This species is probably threatened by introduced predatory fish (Oncorhynchus mykiss), and by the canalisation of spring water towards local towns and villages for domestic use. In addition, the impacts of livestock farming (sheep and goats) have resulted in overgrazing and chemical pollution of waterways from sheep dips.
Conservation Underway
The range of the species is within the Somuncura Provincial Reserve, although there are no specific conservation measure ongoing for this species, and additional protection and maintenance of existing habitat is still urgently required.
Conservation Proposed
The Somuncura Provincial Reserve is currently is poorly managed with regard to biodiversity conservation, and there is little real protection for the Somuncura frog. Strengthening the management of its existing protected area is necessary, and further field research is needed to determine the current population status of the species. All information collected should be used to develop a Conservation Action Plan for this species, addressing all relevant threats and determining the best way to conserve remaining populations. Education material and presentations about this species would be beneficial to inform local people of the value and uniqueness of this species. All conservation decision making should then occur via a consultative and participatory process so that local stakeholders are informed and land uses are modified in a way that is as beneficial as possible for all.

In addition to conserving native habitat for this species, the IUCN Technical Guidelines for the Management of Ex situ Populations, part of the IUCN Red List of Threatened Species, recommend that all Critically Endangered species should have an ex situ population managed to guard against the extinction of the species. An ex situ population is ideally a breeding colony of a species maintained outside of its natural habitat, giving rise to individuals from that species that are sheltered from problems associated with their situation in the wild. This can be located within the species’ range or in a foreign country that has the facilities to support a captive breeding programme for that species. Since the Somuncura frog is categorised as Critically Endangered, the possibility of a captive breeding programme for this species should be investigated.
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