AT A GLANCE
- Common Name: Corsican Painted Frog
- Scientific Name: Discoglossus montalentii
- Category: Amphibians
- Subcategory: Frogs & Toads
- Range: Endemic exclusively to the central mountainous spine of the Mediterranean island of Corsica (France)
- Habitat Type: Fast-flowing, cold mountain streams, springs, river pools, and damp alder and beech forests from 300 to 1,900 meters elevation
- IUCN Red List Status: Near Threatened
- Lifespan: 6 to 10 years in the wild
- Diet: Carnivorous/Insectivorous (aquatic insect larvae, stoneflies, caddisflies, beetles, earthworms, and spiders)
- Average Size/Weight: 5 to 6.5 cm in snout-vent length; 15 to 30 g in weight
- Key Defining Feature: Compact, smooth-skinned mountain frog with a blunt snout, long fourth toe, and relatively uniform dark olive-brown or chestnut coloration lacking bold spots
Overview
The Corsican Painted Frog (Discoglossus montalentii), also known as the Mountain Painted Frog, is a secretive and primitive anuran amphibian endemic solely to the rugged mountain massifs of Corsica. Discovered and described as a distinct species in the late 20th century, it is evolutionary adapted to cold, fast-flowing alpine torrents, in contrast to its lowland sister species, the Tyrrhenian Painted Frog (Discoglossus sardus). With its stout body, disc-like tongue, and cryptic granite-colored skin, it hides among submerged boulders in high-altitude mountain valleys, serving as an irreplaceable emblem of Corsican island endemism.
Biology and Physical Characteristics
Discoglossus montalentii is a medium-sized, stockily built frog with a relatively flattened head and a remarkably blunt, rounded snout. Its skin is smooth or sparsely covered in tiny, flattened warts. Unlike other painted frogs that exhibit bold, wildly polymorphic patterns of stripes and spotted ocelli, the Corsican Painted Frog is distinctly unicolored and dark: its dorsal surface is typically a uniform dark chestnut-brown, bronze, or olive-grey, sometimes accompanied by faint reddish or dark marbling. Its ventral surface is pale yellowish or dirty grey. A diagnostic anatomical feature separating it from D. sardus is its elongated fourth hind toe and shorter, more muscular hind limbs adapted for crawling between submerged river stones rather than long-distance jumping.
Behavior and Ecology
Strictly linked to clean, cold mountain waters, the Corsican Painted Frog is nocturnal and semi-aquatic. By day, it stays submerged beneath granite boulders in mountain stream pools or under wet moss mats along cascades. At night, it emerges to forage on the rocky stream banks, capturing aquatic and terrestrial invertebrates. Like other discoglossid frogs, its tongue is round and fixed to the floor of the mouth, meaning it lunges with its entire body to snatch prey. Breeding occurs in spring and early summer in slow-flowing stream eddies and rock pools. Males emit quiet, muffled clicking calls underwater; females deposit several hundred small, gelatinous eggs loosely on the stream bed, where tadpoles develop in cold, oxygen-rich waters.
Conservation and Human Impact
The Corsican Painted Frog is classified as Near Threatened on the IUCN Red List due to its restricted geographical distribution (less than 5,000 square kilometers) and its strict dependence on pristine alpine watercourses. Threats include the abstraction of mountain stream water for irrigation and tourism, sedimentation from road works, and the catastrophic impact of non-native predatory trout (Salmo trutta) stocked in alpine headwaters, which heavily prey on frog eggs and tadpoles. It is protected under Appendix II of the Bern Convention and Annex II and IV of the EU Habitats Directive.
Interesting Factoid
The Corsican Painted Frog was only recognized by science as a distinct species in 1984, having remained hidden for centuries in Corsica’s high-altitude granite streams because it looks so similar to the common lowland painted frog.