Description
Females are slightly larger than males and grow up to 160mm in length. These large newts are unmistakable with any other species. There is a dark stripe through the eye. The warty skin has a black background with a green marbled pattern. The belly is black with small white spots in the nominate subspecies, while this pattern in the smaller subspecies, T. m. pygmaeus, is augmented with yellow markings and larger white spots (Griffiths 1996).

During the aquatic phase, the male develops a large dorsal and caudal crest. This crest shows a vertical black and green striping pattern and is not serrated, but is undulated laterally. Females do not develop a dorsal crest but instead have a permanent bright orange vertebral stripe. The tail does develop a crest in females, but this is much lower than that of the males. Males have a bright light lateral stripe along the tail and a stronger developed cloaca. During the terrestrial stage the skin gets a velvet-like texture and becomes water-repellant, and the green pattern becomes brighter. The dorsal and caudal crests diminish greatly, although they do not disappear entirely in the males (Noellert and Noellert 1992)

Distribution and Habitat

Country distribution from AmphibiaWeb's database: France, Portugal, Spain. Introduced: Netherlands.

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (29 records).

T. marmoratus has its centre of origin in Western Europe. Its actual distribution is restricted to sectors within the Mediterranean and the Atlantic region in the Iberian Peninsula - except for the dry southeastern part - and in southern France, up to Paris. The distribution along the northern border, in France, is patchy and unstable, because of the presence of its relative T. cristatus in the area. Both species hybridise when reproducing in the same body of water. The mosaic-like distribution of both species in the area of sympatry in central France, could be explained by the effect of competition between the species in interbreeding populations, described as reproductive self-destruction, and effecting ecological isolation. No competition with co-occurring Triturus species seems to be affecting the distribution there. Interruptions in the map of T. marmoratus distribution in Spain can be partly explained by unsuitable climate, as is the case for the higher parts of the Pyrenees and the dry areas of southeastern Spain. In other cases, a lack of inventories might explain blank areas, namely in eastern and southeastern Spain. The two subspecies replace each other over a short distance, in mountain ranges running east-west in central Spain and Portugal, which forms the watershed between the Douro and Tagus rivers. The two subspecies' distribution ranges coincide with different bioclimatic zones. T. m. marmoratus lives in Atlantic and supra-Mediterranean climates; whereas T. m. pygmaeus occurs in meso- and thermo-Mediterranean climates. The species finds its optimum in the lower and middle regions of mountains. Its altitudinal distribution in France ranges from 20m up to 950m in the Massif Central, up to 1035m in the Pyrenees. Its altitudinal distribution is wider on the Iberian Peninsula where the species can be found from sea-level up to about 1800m in Galacia (Northwestern Spain), to 1930m in Portugal and about 2100m in the mountains of central Spain. The highest altitude recorded for the subspecies T. m. pygmaeus is lower, at 1450m (Gasc 1997).

Although this species is usually associated with well-vegetated ponds and woodlands, the species also occurs in more open areas like heathens and agricultural landscapes. Where it occurs sympatrically with T. cristatus it seems to prefer smaller and more vegetated habitats, while T. cristatus occupies more open areas. In the terrestrial phase it is found under logs and rocks, as well as in man-made structures like stone walls (Noellert and Noellert 1992).

Life History, Abundance, Activity, and Special Behaviors
Mating takes place in the water. Males usually enter the water before the females and leave the water later. The reproductive period is dependent on the altitudinal and latitudinal distribution. In northwestern France it lasts from the beginning of March until the middle of August. In central Portugal the breeding period lasts from October until May, while in Esturia it lasts from November to June. The courtship behavior is similar to that of T. cristatus. T. marmoratus produces about twice as many eggs as T. cristatus, but, like in the latter, only half of the embryos develop beyond the tail-bud stage (Griffiths 1996).

A female can produce as many as 200-380 eggs with a diameter of 2mm. Each egg is individually attached to water plants. Larval development is also dependent on the altitudinal and latitudinal distribution. In the northwestern part of the distribution, metamorphosis takes place between the beginning of August and the end of September, while in the Spanish reservation of Doñana larvae could be found between December and May. Larvae grow op to 70-90mm in total length. Sexual maturity is reached at an age of about 5 years. Longevity in the wild is up to 15 years, while in captivity a specimen lived for 25 years.

During the aquatic phase the animals are mostly diurnal, while activity is nocturnal during the terrestrial phase. In the northern parts of its distribution, hibernation usually occurs under water. In the southern parts of the distribution, hibernation does not occur, but the animals spend the dry summer period on humid places on land.

The diet includes various invertebrates, but can also include larvae of T. boscai or larvae of its own species.

When threatened the tail is erected and swayed from side to side. This display is usually accompanied by an elevation of the rear trunk (Noellert and Noellert 1992).

Trends and Threats
T. marmoratus is protected by law in every country where it occurs. However, specimens are still collected for the pet trade and are for sale in the Netherlands and Germany for instance. T. marmoratus is an endangered species in central France and probably less so in southern France.

The species is considered not in danger in Spain and Portugal. Nevertheless, loss and change of habitats are serious threats in the whole area, caused by agricultural intensification and loss and pollution of fresh water. T. m. pygmaeus is especially threatened by the growing exploitation of ground water (Gasc 1997). Populations that interbreed with T. cristatus should be monitored more carefully, because the reduced viability of the hybrids reduces the reproductive capacity of each species (Noellert and Noellert 1992).

Possible reasons for amphibian decline

General habitat alteration and loss
Intensified agriculture or grazing
Drainage of habitat
Local pesticides, fertilizers, and pollutants
Long-distance pesticides, toxins, and pollutants
Intentional mortality (over-harvesting, pet trade or collecting)

References

Gasc, J.-P. (1997). Atlas of Amphibians and Reptiles in Europe. Societas Europaea Herpetologica, Bonn, Germany.

Griffiths, R.A. (1996). Newts and Salamanders of Europe. T. and A. D. Poyser, London.

Nöllert, A. and Nöllert, C. (1992). Die Amphibien Europas. Franckh-Kosmos Verlags-GmbH and Company, Stuttgart.

Stumpel-Rieks, S. E. (1992). Nomina Herpetofaunae Europaeae. AULA-Verlag, Wiesbaden.

Species Account Citation: AmphibiaWeb 2017 Triturus marmoratus: Marbled Newt <https://amphibiaweb.org/species/4300> University of California, Berkeley, CA, USA. Accessed Dec 22, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 22 Dec 2024.

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