The Danube crested newt or Danube newt (''Triturus dobrogicus'') is a species of

newt A newt is a salamander in the subfamily Pleurodelinae. The terrestrial juvenile phase is called an eft. Unlike other members of the family Salamandridae, newts are semiaquatic, alternating between aquatic and terrestrial habitats. Not all aqua ...

found in central and eastern Europe, along the basin of the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , pa ...

river and some of its tributaries and in the

Dnieper } The Dnieper () or Dnipro (); , ; . is one of the major transboundary rivers of Europe, rising in the Valdai Hills near Smolensk, Russia, before flowing through Belarus and Ukraine to the Black Sea. It is the longest river of Ukraine and B ...

delta. It has a smaller and more slender body than the other crested newts in genus ''

Triturus ''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 thei ...

'' but like these, males develop a conspicuous jagged seam on back and tail during breeding season. For half of the year or longer, adults live in slow-flowing river margins, lakes, or ponds, where reproduction takes place. Males perform a

courtship display A courtship display is a set of display behaviors in which an animal, usually a male, attempts to attract a mate; the mate exercises choice, so sexual selection acts on the display. These behaviors often include ritualized movement ("dances"), ...

, and females lay around 200 eggs individually onto leaves of aquatic plants. Larvae develop two to four months in the water before reaching

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

. For the remainder of the year, the newts live in shady land habitats, usually forests. Although not yet considered threatened, Danube crested newt populations have declined significantly, the reason being mainly

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

. The species is protected by law in the European Union.

Taxonomy

The Danube crested newt was described as a variety of the

northern crested newt The northern crested newt, great crested newt or warty newt (''Triturus cristatus'') is a newt species native to Great Britain, northern and central continental Europe and parts of Western Siberia. It is a large newt, with females growing up to ...

(''Triturus cristatus'') by C. Kiritzescu in 1903. Later, it was considered a

subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

until genetic analysis supported its recognition as a separate species in the crested newt

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

. The northern crested newt is its

sister species In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

, according to

phylogenomic Phylogenomics is the intersection of the fields of evolution and genomics. The term has been used in multiple ways to refer to analysis that involves genome data and evolutionary reconstructions. It is a group of techniques within the larger fields ...

studies. Separated populations from the

Danube Delta The Danube Delta ( ro, Delta Dunării, ; uk, Дельта Дунаю, Deľta Dunaju, ) is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Ro ...

and the

Pannonian Basin The Pannonian Basin, or Carpathian Basin, is a large Sedimentary basin, basin situated in south-east Central Europe. The Geomorphology, geomorphological term Pannonian Plain is more widely used for roughly the same region though with a somewh ...

(see section ''Distribution and habitats'') were described as two subspecies, ''T. dobrogicus dobrogicus'' and ''T. dobrogicus macrosoma'', in 2000. Later genetic study, however, did not support the distinction of these two forms.

Description

Measuring long in total, sometimes up to in females, the Danube crested newt is the smallest crested newt species. It has a more slender, elongate body than the other species, well adapted to swimming, with a narrow head and relatively short limbs. This body shape has evolved through an increase in the number of

rib In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...

-bearing

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

: there are 16–17 of them in ''T. dobrogicus'', the highest number among the crested newts. The Danube crested newt's back and sides are dark brown with black spots and white stippling. The belly is orange to red (in other crested newts, it is usually yellow or orange–yellow), with small or medium-sized black blotches that have sharp edges. Like all crested newts, ''T. dobrogicus'' males develop a crest on their back and tail during breeding phase, which can be quite high and jagged, usually starts between the eyes and nostrils, and is interrupted at the tail base. Another feature of males at breeding season is a bluish-white stripe along the tail. Females can sometimes have a yellow stripe along the back, similar to the

Italian crested newt The Italian crested newt (''Triturus carnifex'') is a species of newt in the family Salamandridae. Habitat ''Triturus carnifex'' is found in parts of the Balkans and Italy. It is an aquatic breeder that can spend up to four months in the water ...

(''T. carnifex'').

Distribution and habitats

The Danube crested newt is found in three

allopatric Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...

areas of distribution from central to eastern Europe: *''Pannonian basin'': From easternmost

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

through

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

(small part in the southeast),

Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the s ...

, Hungary, northern

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

Bosnia-Hercegovina Bosnia and Herzegovina ( sh, / , ), abbreviated BiH () or B&H, sometimes called Bosnia–Herzegovina and often known informally as Bosnia, is a country at the crossroads of south and southeast Europe, located in the Balkans. Bosnia and H ...

(marginally), northern

Serbia Serbia (, ; Serbian language, Serbian: , , ), officially the Republic of Serbia (Serbian language, Serbian: , , ), is a landlocked country in Southeast Europe, Southeastern and Central Europe, situated at the crossroads of the Pannonian Bas ...

to the east of

Romania Romania ( ; ro, România ) is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern, and Southeast Europe, Southeastern Europe. It borders Bulgaria to the south, Ukraine to the north, Hungary to the west, S ...

and southeast of

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

(

Transcarpathian region The Zakarpattia Oblast ( uk, Закарпатська область, Zakarpatska oblast) is an administrative oblast located in western Ukraine, mostly coterminous with the historical region of Carpathian Ruthenia. Its administrative centre is ...

). This includes the middle floodplains of the

river and some of its tributaries, including the

Drava The Drava or Drave''Utrata Fachwörterbuch ...

Sava The Sava (; , ; sr-cyr, Сава, hu, Száva) is a river in Central and Southeast Europe, a right-bank and the longest tributary of the Danube. It flows through Slovenia, Croatia and along its border with Bosnia and Herzegovina, and finally th ...

and

Tisza The Tisza, Tysa or Tisa, is one of the major rivers of Central and Eastern Europe. Once, it was called "the most Hungarian river" because it flowed entirely within the Kingdom of Hungary. Today, it crosses several national borders. The Tisza be ...

. *''Lower Danube and Danube delta'': Separated from the Pannonian basin by an area where the northern crested newt occurs, this central part ranges from southern Romania, northern

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...

, and small parts of southern

Moldova Moldova ( , ; ), officially the Republic of Moldova ( ro, Republica Moldova), is a Landlocked country, landlocked country in Eastern Europe. It is bordered by Romania to the west and Ukraine to the north, east, and south. The List of states ...

to the

Odessa region Odesa Oblast ( uk, Оде́ська о́бласть, translit=Odeska oblast), also referred to as Odeshchyna ( uk, Оде́щина) is an oblast (province) of southwestern Ukraine, located along the northern coast of the Black Sea. Its administr ...

of southern Ukraine. *''

delta'': This small area of distribution in southern Ukraine was reported in 2005. It is now isolated by

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without trees apart from those near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the temperate grasslands, ...

from the Danube basin, but it has been suggested that these areas were connected through

marshlands A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...

during the

last glacial maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eur ...

, when the level of the

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...

was around 100 metres lower than today. This range may also extend to the lower basins of the

Dniester The Dniester, ; rus, Дне́стр, links=1, Dnéstr, ˈdⁿʲestr; ro, Nistru; grc, Τύρᾱς, Tyrās, ; la, Tyrās, la, Danaster, label=none, ) ( ,) is a transboundary river in Eastern Europe. It runs first through Ukraine and th ...

and Bug rivers. NPDonauAuen

In addition to the northern crested newt to the north, the Danube crested newt's range borders that of the Italian crested newt (''T. carnifex'') in the west, and that of the Macedonian (''T. macedonicus'') and

Balkan The Balkans ( ), also known as the Balkan Peninsula, is a geographical area in southeastern Europe with various geographical and historical definitions. The region takes its name from the Balkan Mountains that stretch throughout the who ...

(''T. ivanbureschi'') crested newts in the south. Compared to the other crested newt species, the Danube crested newt is more adapted to life along a river system and frequently occurs in flowing water and together with fish. Typical breeding sites are slow-flowing river margins,

oxbow lakes An oxbow lake is a U-shaped lake or pool that forms when a wide meander of a river is cut off, creating a free-standing body of water. In South Texas, oxbows left by the Rio Grande are called '' resacas''. In Australia, oxbow lakes are calle ...

, flooded

marshland A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at ...

, larger ponds, or ditches, provided abundant underwater vegetation is available. During land phase, the newts live in deciduous forests or groves, bushlands, or meadows.

Lifecycle and behaviour

Danube crested newts have the longest aquatic phase in the genus ''Triturus''. Adults move to their breeding sites in February or March and usually stay there for six months; occasionally, they may even stay longer or return to the water in autumn. Males court females with a

display Display may refer to: Technology * Display device, output device for presenting information, including: ** Cathode ray tube, video display that provides a quality picture, but can be very heavy and deep ** Electronic visual display, output devi ...

of ritualised body movements. When they have gained the female's interest, they guide it over a

spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...

they deposit on the ground, which the female then takes up with her

cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...

. The eggs are fertilised internally. As in other crested newts, a female lays around 200 eggs per season, which are folded individually into leaves of aquatic plants. Eggs and larvae are smaller than in the other crested newt species, and they take longer (two to four months) until they reach

and leave the water. Both in water and on land, the newts are largely nocturnal. In their aquatic habitats, they hide under vegetation, and on land, they use structures such as logs, rocks, or small animal burrows for cover. They feed mainly on different

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

, but in the water may also prey on

tadpole A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found i ...

s and smaller newts. Predators include

herons The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychus ...

and other birds, snakes such as the

grass snake The grass snake (''Natrix natrix''), sometimes called the ringed snake or water snake, is a Eurasian non-venomous colubrid snake. It is often found near water and feeds almost exclusively on amphibians. Subspecies Many subspecies are recogniz ...

, and various carnivorous mammals.

Threats and conservation

The population of the Danube crested newt has declined significantly, and the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

has assessed its conservation status as "

least concern A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...

". The main threat is

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

by humans, especially through drainage, damming, or pollution. Hybridisation with other crested newt species and a loss of breeding ponds because of decreasing spring rain in the southern range (possibly due to

global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

) are also seen as threats. Like the other crested newts, ''T. dobrogicus'' is listed in the

Berne Convention The Berne Convention for the Protection of Literary and Artistic Works, usually known as the Berne Convention, was an international assembly held in 1886 in the Swiss city of Bern by ten European countries with the goal to agree on a set of leg ...

(appendix II) and the EU

Habitats Directive The Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora) is a directive adopted by the European Community in 1992 as a response to the Berne Convention. The E ...

(annexes II and IV), and capture, disturbance, killing, trade, and destruction of habitats are prohibited.

References

External links

AmphibiaWeb - ''Triturus dobrogicus''
* {{Good article Triturus Amphibians described in 1903 Amphibians of Europe Taxonomy articles created by Polbot