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''Triturus'' is a genus of newts comprising the crested and the marbled newts, which are found from Great Britain through most of continental Europe to westernmost Siberia, Anatolia, and the Caspian Sea region. Their English names refer to their appearance: marbled newts have a green–black colour pattern, while crested newt males develop a conspicuous jagged seam on their back and tail during their aquatic breeding phase. Crested and marbled newts live and breed in vegetation-rich ponds or similar aquatic habitats for two to six months and usually spend the rest of the year in shady, protection-rich land habitats close to their breeding sites. Males court females with a ritualised display, ending in the deposition of a spermatophore that is picked up by the female. After fertilisation, a female lays 200–400 eggs, folding them individually into leaves of water plants. Larvae develop over two to four months before metamorphosing into land-dwelling juveniles. Historically, most European newts were included in the genus, but taxonomists have split off the alpine newt (''Ichthyosaura''), the small-bodied newts (''Lissotriton'') and the banded newts (''Ommatotriton'') as separate genera. The closest relatives of ''Triturus'' are the European brook newts (''Calotriton''). Two species of marbled newts and six species of crested newts, formerly considered subspecies, are accepted, with one additional crested newt species suspected. Their ranges are largely contiguous but where they do overlap, hybridisation may take place. Although not immediately threatened, crested and marbled newts suffer from population declines, caused mainly by habitat loss and fragmentation. Their aquatic breeding sites as well as the cover-rich, natural landscapes they depend on during their terrestrial phase are both affected. All species are legally protected in Europe, and some of their habitats have been designated as special reserves. ==Taxonomy and systematics== The genus name ''Triturus'' was introduced in 1815 by the polymath Constantine Samuel Rafinesque.〔 The type species, the northern crested newt (''Triturus cristatus''), was originally described as ''Triton cristatus'' by Josephus Nicolaus Laurenti in 1768, but Linnaeus had already used the name ''Triton'' for a genus of sea snails ten years before.〔〔 Until the end of the 20th century, ''Triturus'' included most European newt species, but the genus was substantially revised after it was shown to be polyphyletic.〔 Three separate genera now accommodate other former members of the genus: the small-bodied newts (''Lissotriton''), the banded newts (''Ommatotriton''), and the alpine newt (''Ichthyosaura''). The monophyly of the genus ''Triturus'' in the strict sense is supported by molecular data〔 and synapomorphies such as a genetic defect causing 50% embryo mortality (see below, ''Reproduction''). Their closest relatives are the European brook newts (''Calotriton'').〔 As of 2015, the genus contains eight accepted species: two in the marbled newts and six in the crested newts. Both groups were long considered as single species, ''Triturus marmoratus'' and ''T. cristatus'', respectively. Substantial genetic differences between subspecies were however noted and eventually led to their recognition as full species.〔 The Balkan–Anatolian crested newt (''T. ivanbureschi''), formally described in 2013, probably conceals two species.〔 The crested newts are often collectively referred to as "''T. cristatus'' superspecies".〔 Molecular phylogenetic data helped clarify relationships within the genus: A 2011 phylogeny based on complete mitochondrial DNA resolved all divergences in the genus with high statistical support:〔 The crested and the marbled newts are sister groups, and within the crested newts, the Balkan–Asian group around ''T. karelinii'' and ''T. ivanbureschi'' is sister to the remaining species, results consistent with other studies.〔〔 The mitochondrial analysis also supports the northern and the Danube crested newt (''T. dobrogicus''), as well as the Italian (''T. carnifex'') and the Macedonian crested newt (''T. macedonicus''), respectively, as sister species, but analysis of nuclear DNA gave some conflicting results regarding those divergences.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Triturus」の詳細全文を読む スポンサード リンク
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