Tyrrhenian painted frog
(Discoglossus sardus)
The Tyrrhenian painted frog is so-called because it inhabits a number of French and Italian Islands around the Tyrrhenian Sea, as well as the Italian peninsular of Monte Argentario.  It is relatively common in Sardinia and Corsica, but stream damming for increasing water demands has led to the loss of breeding sites and small island populations may be threatened.  D. sardus is extremely similar in appearance to the less widespread D. montalentii, also native to Corsica, and as such identification can be tricky.  The painted frog lineage has been evolving independently of any other for over 200 million years, making it older than many species of dinosaur.

Urgent Conservation Actions
Italy and France.
Evolutionary Distinctiveness
Order: Anura
Family: Alytidae
The Alytidae are an ancient family found in Europe, the Middle East and Northwestern Africa, and are comprised of the midwife toads (Alytes) and painted frogs (Discoglossus).  Overall, this family is now named after the midwife toads.  The family name was formerly Discoglossidae or ‘disc-tongued frogs’ because, unlike the slender tongues of many amphibians, midwife toads and painted frogs possess a round and flattened tongue.  They diverged from the fire bellied toad lineage and all other amphibians about 210 millions years ago at the end of the Triassic period, around the same time that the first primitive mammals started to appear.  The midwife toad family therefore evolved at the feet of some of the earliest dinosaurs, and survived the dinosaur’s demise nearly 150 million years later.

Within the family Alytidae, the painted frogs diverged from the midwife toads about 155 million years ago, about 5 million years before the first birds started to appear in the fossil record.  Painted frogs are more different from their closest relatives in terms of evolutionary time than kangaroos are to elephants, as they started to evolve independently about 10 million years before the common ancestor of these two mammal groups.

The number of species in this group has been the subject of debate since the discovery of Discoglossus in the 1830s.  For over a hundred years it was contested whether the two described forms, D. pictus and D. sardus, even deserved subspecies status.  Developments in molecular biology allowing the study of genetic make-up have revealed a high level of divergence within the group, and have identified a number of new species.  It is currently being debated whether there are six or seven species within the Discoglossus genus.  Discoglossus sardus is thought to have been isolated from all other living Discoglossus species over 5 million years ago, meaning that it has been evolving independently as long as humans and chimpanzees.
Unlike their closest relatives the midwife toads, which are relatively stocky and toad-like, painted frogs have classic frog features such as a slim waist, long legs and webbed toes on their hind feet.  Their pupils are round, triangular or ‘upside-down teardrop’ shaped, and their skin is generally smooth and shiny with small but visible warts.  The name comes from the variety of colour variations and patterns seen in the group; some are plain in colour whilst others have stripes, spots, bands and blotches of varying tones. 

Tyrrhenian painted frogs can be dark brown, dark grey, reddish or red brown.  Some individuals have dark brown spots and others are plain.  They are very similar in appearance to the less widespread Corsican painted frog Discoglossus montalentii, but can be distinguished by minor morphological differences like finger shape and leg length.  Early research on D. sardus may be attributed to either D. sardus or D. montalentii, as they have only recently been recognised as separate species.
The disc-shaped tongues seen in this group of frogs are not long and free to be flicked out of the mouth to capture insects in mid-air.  Instead, invertebrate prey items are gobbled straight into the mouth whilst the frog is on land or in water.  On Corsica the Tyrrhenian painted frog is sympatric with the Corsican painted frog D. montalentii, meaning that they are found in overlapping geographic areas but do not interbreed.  In some localities they are even syntopic, meaning that not only do their ranges overlap but they can actually share the same habitat within the same geographic area.  Studies have shown that differences in foraging strategy explain how the two close relatives can coexist, as D. sardus mainly captures prey items whilst on land, while D. montalentii takes prey from land and water in similar proportions.

Another adaptation to living side by side with a closely related species is ‘acoustic partitioning’, or the evolution of very distinct calls to prevent interbreeding.  During the breeding season, male painted frogs develop nuptial pads on their fingers and under their chin and belly – these are large, thickened pads which help the male to grip on to the female as she lays her eggs, so that he can avoid slipping off before being able to fertilise them!  Females of this species deposit eggs singularly or in small clumps around aquatic vegetation in streams.  Tadpoles hatch out after a few days and metamorphose into froglets a few weeks later.
D. sardus can live in a range of habitat types and is thought to be able to tolerate some habitat disturbance.  It inhabits both coniferous and broadleaf woodlands, maccia (Mediterranean shrubland) and open areas.  Aquatic habitats include still or slow-running waters and even slightly brackish pools.
The Tyrrhenian painted frog is known from Sardinia (including the Maddalena Archipelago and San Pietro Island), Corsica (excluding the central highlands), the Italian peninsular Monte Argentario, nearby Italian islands Giglio and Montecristo, and the French islands of Port-Cros and Le Levant. 

In Corsica, its distribution overlaps with that of the closely related Corsican painted frog (D. montalentii).  There seems to be some degree of differentiation in habitat preference, however, with D. montalentii preferring running water at higher elevations and D. sardus preferring slow running or stagnant water at lower elevations.  In Corsica, D. sardus is found from sea level up to 1300 metres, whereas in Sardinia it has been recorded up to 1750 metres above sea level.
Population Estimate
Relatively common in Sardinia and Corsica.  On the French island of Port-Cros, populations have increased following the eradication of two non-native fish species (Gambusia and Scardinus erythrophalmus).  It is possible that peninsular populations in Tuscany and some of the small island populations are threatened.
Population Trend
The IUCN estimates that the overall population trend for D. sardus is stable.
The IUCN has categorised the Tyrrhenian painted frog as Least Concern in the 2008 Red List of Threatened Species.
Although this species is not thought to be seriously threatened at present, increased water requirements for tourism on Corsica and possibly Sardinia have led to the loss of many aquatic breeding sites through the damming of streams.  Woodland habitats have also been lost.   Populations inhabiting small islands are vulnerable due to their likely small size.
Conservation Underway
D. sardus is strictly protected by EU legislation, under the Bern Convention (Annex II) and the Natural Habitats Directive (Annex IV).  It is also protected by national legislation in Italy, and is known to occur in two protected parks in Sardinia (Parco Regionale dei Sette Fratelli and Parco Nazionale del Gennargentu e Golo di Orosei) and one in France (Parc national de Port-Cros).
Conservation Proposed
Investigations into the genetic diversity of this species are recommended by the IUCN Red List.  Other sources suggest the small island populations require research attention.
AmphibiaWeb           http://amphibiaweb.org/

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Zangari, F., Cimmaruta, R. and Nascetti, G. 2006. Genetic relationships of western Mediterranean painted frogs based on allozymes and mitochondrial markers: evolutionary and taxonomic inferences (Amphibia, Anura, Discoglossidae). Biological Journal of the Linnean Society 87:515-536.

Distribution dataset:  IUCN 2008. 2008 IUCN Red List of Threatened Species. http://www.iucnredlist.org

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