Chile Darwin’s frog  (Rhinoderma rufum)

Classified as Critically Endangered (CR) on the IUCN Red List (1).

The Chile Darwin’s frog is an extremely unusual amphibian that was last seen around 1980, and may already be extinct (1) (2) (3). It is a small species with slender limbs and extensively webbed toes. The presence of a fleshly proboscis that projects pointedly from the tip of the snout is a distinctive feature. The colouration of the back is highly variable, with some specimens exhibiting various shades of brown, while others range from pale to dark green. Underneath, the skin is dotted with black and white splotches (2) (3).

For a long time the Chile Darwin’s frog was believed to be a local variant of a species known as Darwin’s frog (Rhinoderma darwinii), discovered by Charles Darwin during his voyage aboard the Beagle. Although the two are now recognised as separate species, R. rufum is still commonly referred to as the Chile Darwin’s frog (4).

The Chile Darwin’s frog is only known from Central Chile (1) (2) (3).

The Chile Darwin’s frog has been found in leaf litter near slowly moving water in wet temperate mixed forest and also in bogs surrounded by forest. It has been recorded at elevations from sea level up to 500 metres (1) (2) (3).

The two Rhinoderma species are commonly referred to as ‘mouth brooding’ frogs because of their highly unusual form of parental care (2) (3). Following mating, the female Chile Darwin’s frog lays a clutch of 12 to 24 tiny eggs on moist ground. Around eight days later, when the larvae in the eggs begin to move, the male ingests the eggs and incubates them in the vocal sac. Once the larvae have developed sufficiently, the male regurgitates the tadpoles into a stream where they complete their metamorphosis (1) (2) (3).

The Chile darwin’s frog is a terrestrial species that is most active during the day. It feeds on small insects and other invertebrates, and is thought to hunt by staying still and waiting for prey to move within striking distance (2) (3).

The causes of the Chile Darwin’s frog precipitous decline and subsequent disappearance are not well understood. It is thought that habitat loss through the planting of plantations and residential development may have had some impact, whilst climate change and possibly disease might have caused declines in existing areas of suitable habitat (1) (3).

Urgent survey work is vital to determine whether the Chile Darwin’s frog still survives. In addition, suitable habitat for this species needs to be surveyed to determine whether amphibian pathogens such as the chytrid fungus (not previously reported in Chile), are present in the area. Given the threat of disease, it would likely be necessary to establish an ex-situ population if surviving individuals are ever discovered (1) (3).

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

To find out more about the Chile Darwin’s frog and other threatened species with unique evolutionary histories, visit: 

• Evolutionarily Distinct and Globally Endangered (EDGE):
  http://www.edgeofexistence.org/amphibians/species_info.php?id=590