Species account

Description
Medium-sized newt with relatively flat body. Paratoid glands not well-defined. Head depressed, much longer than broad, snout semi-elliptical, upper jaw extending over lower jaw, upper lips with well-developed labial folds. No gular fold. Tongue small, sub-elliptical, free at the sides. Lungs rudimentary. Tail about as long as snout-vent length, broad at the base and increasingly compressed laterally, ending in an obtuse point, with small upper and lower crests, the latter beginning half way along the tail. Fingers rather elongate and slender. Dorsal skin smooth or finely tubercular above, venter completely smooth. Spurs on hind legs of males strongly protruding, especially in older specimens (Carranza & Amat, 2005).

Colour brown or olive above, variegated with greenish, yellowish or light grey with an orange-reddish vertebral stripe. Venter is whitish on the sides and yellowish or reddish along the centre, with irregularly distributed black spots on belly and throat (Carranza & Amat, 2005). Male cloaca hook-extended backwards with opening directed upwards; female cloaca slightly protruding or conical with opening directed back downwards (Rimpp & Thiesmeier, 1999). Males are longer and heavier than females and show proportionally longer and heavier heads, shorter cloacas, longer tails and longer hind limbs (Bovero et al., 2003).

Total length 11-12 cm, max. 15 cm.

Diagnosis
Small-sized brownish newt, smooth-skinned in water, slightly rough-skinned on land. Head long. Male with spurs on hind legs. No dorsal crest in breeding season.

Eggs and larvae
Eggs only known from observations in captivity. The female lays the eggs individually under rocks and in cracks with the help of her tubular, extended cloaca, in captivity also on gravel substrate and hidden in the sand. A female may lay between 57 and 221 eggs per season, extended over a period of several months. Eggs measure 3-3.3 mm in diameter, 4-5 mm including the gelatinous capsule. Embryonic development takes 37.6 days on average at a water temperature of 15°C and 12.7 days at 24.5°C. Larvae are 8.8-14.5 mm upon hatching. Duration of larval development also depends on temperature. At 15°C it takes 376-453 days, at 20.5°C 184-260 days. At metamorphosis juveniles are fairly large with 43.8-64.0 mm total length (Alcher, 1980a, 1980b; Rimpp & Thiesmeier, 1999). Developing larvae are light brown and can be recognized by an elongated rectangular head. They have a rounded tail tip and are similar to larvae of Euproctus montanus except for the dorsal fin, which extends further onto the back than in the latter species (Bedriaga, 1897; Miaud & Muratet, 2004).
Euproctus platycephalus shows a tendency to paedomorphosis: almost sexually mature specimens with gill vestiges are reported. Juvenile newts have been found on land under tree bark in a forest close to the breeding stream. They are coloured dark with a red vertebral stripe, bright green spots behind the eyes and on body and tail; limbs brown-grey (Rimpp & Thiesmeier, 1999).
Sexual maturity is attained between two and five years after metamorphosis; the age of animals from four populations that were studied ranged from 4 to 13 years (Angelini et al., 2008). In captivity animals reached adulthood in the third year after egg deposition (Rimpp & Thiesmeier, 1999).

Distribution
Endemic to the Mediterranean island of Sardinia, Italy. Its range is restricted to the eastern part of the island, from the Limbara mountains in the North, via Gennargentu in the centre to the Sarrabus mountains in the South, and between Baunei in the East and Monte Linas in the West (Lecis & Norris, 2003; Lanza et al., 2007; IUCN, 2011).

Habitat
This is a montane species. The aquatic habitat consists of permanent and temporary stagnant pools, mountain streams, calm parts of rivers and small mountain lakes. The terrestrial habitat is riverine scrub or woodland close to the water. There the animals are found under stones and in root zones of bushes and trees in wasteland. The species occurs between 50 and 1,800 m, with most records from the 400-900 m zone (Rimpp & Thiesmeier, 1999; Lanza et al., 2007; IUCN, 2011).

Behaviour
Most animals are found active at water temperatures between 9-14°C. Main activity is after dark (Pieroni et al., 2008). In harsh periods in winter and summer they may hide under logs and stones on land, but individuals may be found in water all year round. Food consists of aquatic invertebrates such as adult and larval arthropods, worms and molluscs. They have a preference for chironomid larvae and also eat eggs of their own species (Sotgiu et al., 2008). Potential predators are birds, small mammals, salmonid fish and water snakes (Natrix) (Lanza et al., 2007).
Reproduction takes place in water in spring, in April-May, with water temperatures ranging from 9-14°C, and has also been observed after aestivation in autumn (October-November). In winter and mid-summer the newts are less active (Pieroni et al., 2008). In captive animals reproductive activity has been reported all year round except in July-August (Rimpp & Thiesmeier, 1999). The male actively searches for a female with mouth open. If he hits upon a female the male grabs her with his jaws and holds on to her body between neck and cloaca. His tail is laid loosely over the cloacal region of the female, his body arched over that of the female during copulation, and sperm transfer takes place via direct contact of the male and female cloacas. The spurs on his hind legs are used to massage the male’s own cloaca and bring about sperm transfer. Copulation can take between one and three hours, during which one sperm package is delivered. There is no such tight amplexus with the tail as in Euproctus montanus and Calotriton asper (Bedriaga, 1883, 1893, 1897; Thiesmeier & Hornberg, 1990; Rimpp & Thiesmeier, 1999)
The female lays her eggs usually singly and not as a clutch such as Euproctus montanus. The form of parental care by the female as observed in E. montanus has not been observed in E. platycephalus.

Threats and conservation
Major threats to the species are pollution of waterbodies, habitat fragmentation, predation by introduced trout, and prolonged drought. Its decline is not well understood. Chytridiomycosis has been detected in a population in the Sette Fratelli area (Bovero et al., 2008). It is listed as endangered (Stuart et al., 2008; IUCN, 2011).

Observations in captivity
Euproctus platycephalus has been bred in captivity through at least the F3 generation. Reproductive behaviour and development of larvae and juveniles has been described from detailed observations on captive animals. In captivity this species requires water temperatures preferably below 18°C and a rest period of several months with temperatures between 6 and 13° C (Alcher, 1980a, 1981). Tanks should best have a water and a land part, although the animals can most easily be kept aquatic all year round. A water pump is useful to keep the water slowly moving. Captive animals should be given small insects and their larvae. Euproctus platycephalus has lived in captivity for many years and captive breeding is unproblematic. Details of captive maintenance of the two Euproctus species and Calotriton asper are discussed in Alcher (1980a), resp. Thiesmeier & Hornberg (2002).

Comments
The rarity and apparent sensitivity to environmental threats of Euproctus platycephalus is in striking contrast with the ease of breeding this species in captivity.

Euproctus platycephalus on land, near Rio Fluminaddu, Sardinia
© 2010 Max Sparreboom

Euproctus platycephalus in water, Limbara mountains, Sardinia
© 2008 Trenton Garner


Distribution of Euproctus platycephalus © 2011 (IUCN)