Discoglossus Otth, 1837
The following are the seven recognized extant species (ITIS. 2012) within the genus Discoglossus:
D. galganoi (Capula, Nascetti, Lanza, Bullini & Crespo, 1985) Iberian Painted Frog
D. jeanneae (Busack, 1986) Spanish Painted Frog
D. montalentii (Lanza, Naxcetti, Capula & Bullini, 1984) Corsica Painted Frog
D. nigriventer (Mendelssohn & Steinitz, 1943) Hula Painted Frog
D. pictus (Otth, 1837) Painted Frog
D. sardus (Tschudi in Otth, 1837) Tyrrhenian Painted Frog
D. scovazzi (Camerano, 1878) Moroccan Painted Frog
There are two subspecies of D. pictus: D. pictus auritus and D. pictus pictus. The former was originally described as D. auritus by Heron-Royer (1889).
All taxa of the genus are classified by the IUCN as Least Concern, except for the Near Threatened D. montalentii and the Critically Endangered D. nigriventer, the latter which was thought to be extinct up until rediscovery in 2012.
The genus may occur in the following protected areas:
Sardinia: Asinara National Park, Arcipelago di La Maddalena National Park, Gennargentu National ParkTyrrhenian Sea islands: Arcipelago Toscano National Park, Port-Cros National ParkCorsica: Parc naturel régional de CorseSpain: Donana National Park, Sierra Nevada National ParkMorocco: Al Hoceima National Park, Ifrane National Park, Tazekka National ParkAlgeria: Belezma National Park, Djurdjura National Park, El Kala National ParkIsrael: Hula Nature Reserve
Taxon specific protection is present only within the Hula Nature Reserve for D. nigriventer; and within Parc naturel régional de Corse for D. montalentii.
North African species of the genus are threatened by an expanding human population within the genus range, leading to agricultural land conversion, overgrazing and extraction of surface waters to serve the human population. In southern Europe, habitat loss (Gasc, 1997) and fragmentation are threats, as well as the predation incurred by introduction of alien salmonid fishes and alien crustaceans, Procambarus clarkii being a specific example. Additionally, hydroelectric projects are leading to habitat loss in parts of Portugal.
Discoglossus is an anuran clade whose origin can be traced to the Upper Miocene. Extant species of this genus are similar morphologically, and exhibit a circum-Mediterranean Sea distribution. The earliest phylogenetic split within the genus separated D. montalentii from a clade comprising all other species of the genus. D. montalentii is monophyletic for haplotype variation at all loci and has distinctive morphological, bioacoustic, and karyotypic characters. Pabijan et al. found moderate support for a sister-group relationship between the Iberian Peninsula Discoglossus species and the Moroccan D. scovazzi, and high support for a D. pictus/D. sardus clade occurring around the Tyrrhenian basin (Pabijan et al. 2012).
Pabijan et al. explain the speciation of D. galganoi, D. scovazzi, D. pictus and D. sardus as the consequence of a "nearly simultaneous, vicariant diversification". The timing of such speciation is not completely evident, but may have coincided with the ultimate geotectonic rearrangement of the western Mediterranean Sea geography in the Mid-Miocene, or possibly later during the Messinian salinity crisis (Pabijan et al. 2012).
The genus distribution is considered to circumscribe the Mediterranean Basin; however, the occurrences are skewed to the west with extant species ranging from Morocco to Algeria and Tunisia in North Africa (World Wildlife Fund & Hogan, 2007); and the Iberian Peninsula, to France and Italy in Europe. The species D. nigriventer is the sole taxon present in the Middle East, occurring in Israel and possibly Syria (Disi et al. 2012). No extant genus populations occur in Greece, Croatia, Turkey, Lebanon, Egypt, Libya.
The North African species of Discoglossus are associated with streams, cisterns and pools of either fresh or saline water, where breeding occurs in such wetland habitats. The chief ecoregion of occurrence in North Africa is the Mediterranean woodlands and forests (World Wildlife Fund & Hogan, 2007). Terrestrial habitats in North Africa include oak forests, Nerium oleander scrub and archaeological ruins. (Salvador et al. 2009). Individuals can often be discovered hiding under rocks, in crevices and even under the bark of cork oaks (Quercus suber). It is thought that the North African occurrences can endure relatively minor habitat modification.
In southwestern Europe, habitat is generally near streams that traverse woodlands or forests. D montalentii occurrences are near freshwater; however, D. sardus may be found near brackish or freshwater systems. Furthermore, D. sardus occurs in Sardinia (including the Maddalena Archipelago and the island of San Pietro); Corsica and several small islands of the Tyrrhenian sea (Iles d'Hyères, Giglio, Montecristo); and on the Italian mainland, the species is reported from the small peninsular Monte Argentario (Tuscany). D. sardus inhabits a variety of biotopes, from the open, desolate and windy coastal zone between Bonifacio and Cap Pertusato, to the forest streams of la Forêt de Bavella, and from Mediterranean maquis at sea level to mountain conifer forests (Delaugerre and Cheylan, 1992).
On the Iberian Peninsula D. galganoi is separated from D. jeanneae by the Guadalquivir river in the southern part of its distribution, and by the saline lakes in the central part of the Iberian Peninsula. Contact zones between the two species are expected in the eastern portion of the Sierra Morena, near the Sierra de Guadarrama and along the northwestern edge of the Meseta Norte (Garcia-Paris and Jockusch, 1999). D. galganoi is mostly found in or in the direct vicinity of water. They are found in stagnant waters, in swamps and mountain streams and even in brackish waters (Noellert & Noellert, 1992).
Habitat (for D. nigriventer) in the Middle East is restricted to the Hula wetlands in northern Israel, and possibly similar adjacent habitats in Syria. The wetlands of Lake Hula were drained for mainly agricultural purposes in the 1950's, dealing a severe blow to viable habitat in this region (Disi et al. 2012).
Embryonic development takes two to six days, depending on water temperature; at that point tadpoles about three millimeters in length are hatched and begin their diurnally active lifestyle. After 22 to 90 days the larvae metamorphosize to froglets with a snout vent length of about ten millimeters.
Frogs of this genus generally deposit eggs directly in surface waters, and adults provide no noticeable care of the young. This lack of adult parental care separates the genus Disglossus from sister genus Alytes; in particular, species within genus Alytes demonstrate female deposition of eggs that become attached to hindlegs of the adult males, who subsequently carry them prior to depositing the eggs in water (Salvador, 1996).
The age of sexual maturity varies greatly among species within the genus, with rapid maturity of one year for D.. scovazzi to as much as five years for D. galganoi males. Copulation detail has been documented only for some of the species, but is thought that it is generally by terrestrial amplexus. Mating system is polyandrous, with a female mating with a number of males, even within a single breeding season.
Each female can produce up to 4000 to 6000 eggs per season, typically in multiple clutches, with a clutch size of 300 to 1500 eggs. The eggs are laid singularly or in small clumps either (a) on aquatic vegetation or (b) in the benthic zone of the water column (sometimes eventually floating on the water surface). An individual egg is typically about 1.5 to 2.0 millimeters in diameter, within a gelatinous envelope around four times the diameter of the egg itself. In many instances the gelatinous envelopes cling together in a loose mass.