Amongst the 11 species recorded in West Siberia, widely distributed species are the Siberian salamander Salamandrella keyserlingii Dybowski, 1870, the common toad Bufo bufo (Linnaeus, 1758), the moor frog Rana arvalis Nilsson, 1842 and the Siberian wood frog R. amurensis Boulenger, 1886. The eastern and north-eastern periphery of the ranges of the common newt Lissotriton vulgaris (Linnaeus, 1758), the Pallas’ spadefoot toad Pelobates vespertinus (Pallas, 1771), the variable toad Bufotes sitibundus (Pallas, 1771), Pewzow’s toad Bufotes pewzowi (Bedriaga, 1898), the common frog R. temporaria Linnaeus, 1758 and the frogs of Pelophylax ridibundus (Pallas, 1771) complex are located in the region. The green toad Bufotes viridis (Laurenti, 1768) exists in West Siberia outside its native range, as an inadvertently introduced species. Below, we provide a brief description of the distribution, habitats and regional conservation status of all amphibian species inhabiting West Siberia.

Salamandrella keyserlingii Dybowski, 1870

The Siberian salamander is the amphibian species with the largest native range in the world (Poyarkov and Kuzmin 2008). Its range covers the European part of Russia, the Urals and Siberia and spans to the Chukotka and Kamchatka Peninsulas in the east. In the south, the range of the Siberian salamander reaches north Kazakhstan, north China and north Mongolia (Kuzmin 2012). In West Siberia, this species mainly inhabits the taiga zone, entering the tundra zone in the north and the steppe zone in the south through the forested river valleys. In the southeast of the forested areas of West Siberia, the Siberian salamander inhabits birch-aspen, birch-fir and birch-pine forests and swamps. It is common in raised bog areas in the taiga zone (Ravkin et al. 1998, Ravkin et al. 2005, Ravkin et al. 2008). The salamanders typically breed in the water bodies situated in the margins of the raised bog areas in pine forests, in shallow overgrown lakes and temporary water bodies in the interfluves, as well as in roadside and melioration ditches (Kuzmin 2012). At the same time, the salamanders do not inhabit large rivers like Ob, Tom, Ket and their tributaries and large and small water bodies situated in their floodplains (Ravkin et al. 2005, Ravkin et al. 2008).

We report 290 locations where this species was observed in West Siberia, from 67.33°N to 52.04°N in latitude and throughout the whole region longitudinally.

The Siberian salamander is listed in the Red Books of Kurgan Oblast (category III, rare species) (Bolshakov et al. 2012), Omsk Oblast (category III, rare species, under the name “Hynobius keyserlingi”) (Sidorov and Plikina 2015), Altai Krai (category IV, data deficient) (Irisova et al. 2016), Chelyabinsk Oblast (category II, vulnerable) (Bolshakov 2017), Yamalo-Nenets Autonomous Okrug (category III, rare species) (Ektova and Zamyatin 2010) and Sverdlovsk Oblast (category IV, data deficient) (Korytin 2018).

Lissotriton vulgaris (Linneus, 1758)

The territory of West Siberia is inhabited by the nominative subspecies, Lissotriton vulgaris vulgaris (Kuzmin 2012). The majority of the known localities in West Siberia are situated at the border between the forest and forest-steppe zones, where the newts occur in birch-aspen and pine forests. In the valleys of large rivers, the newts prefer forested hills, which are not flooded during the spring floods. In the forest-steppe, the density of the newt populations decreases to the south and south-east with the climate aridisation (Kuzmin 2012). Another limitation of the occurrence of common newts is the presence of water bodies suitable for reproduction. The newts prefer open and well-heated water bodies in forested areas and in river floodplains (Skorinov et al. 2008).

We report 176 registrations. The known northern limit of the distribution is declining to the south when moving to the east (from 62.0°N in Khanty-Mansi Autonomous Okrug to 56.5°N in Kemerovo Oblast). The southern distribution limit follows the transition zone between forest-steppe and steppe zones (from 54.7°N on the west to 51.1°N on the east). In the east, the distribution is limited by the Altai and Kuznetsk Alatau mountains. The easternmost known location is situated in Krasnoyarsk Krai (56.53°N 89.32°E).

The common newt is listed in the Red Books of Tyumen Oblast (category IV, data deficient) (Petrova 2020), Omsk Oblast (category III, rare species, under the name “Triturus vulgaris”) (Sidorov and Plikina 2015), Kemerovo Oblast (category I, endangered) (Skalon 2012), Krasnoyarsk Krai (category IV, data deficient) (Savchenko 2012), Tomsk Oblast (category VI, “a species of aesthetic and scientific value”) (Adam 2013) and Khanty-Mansi Autonomous Okrug (category IV, data deficient) (Vasin and Vasina 2013).

Rana amurensis Boulenger, 1886

The Siberian wood frog is an Asiatic species, which inhabits West and East Siberia, the Far East, North Korea, Manchuria, northern and central Mongolia. Several populations are known north of the Arctic Circle. The southern border of its range runs through southern Siberia to Mongolia, Manchuria and Korea (Kuzmin 2012). The south-western border of the range is situated in Kurgan Oblast. Here, the frog is found in the north-eastern part of the region, where it is confined to the floodplains of rivers and near lake shores (Starikov 2014). It inhabits altitudes of 0–500 m above sea level (Kuzmin 2012). The presence and hydrochemical characteristics of water bodies suitable for wintering is an important factor for the species. In this regard, over most of the range, especially on its periphery, the Siberian wood frog is associated with river floodplains (Kuzmin 2012). On the territory of West Siberia, this species is found from the middle taiga to the southern forest-steppe. In the middle and southern taiga, it prefers floodplain swamps and, to a lesser extent, meadows. The abundance of the species is maximal in the southern taiga (Ravkin et al. 1998).

We registered 115 records of the Siberian wood frog. The western border of the species range goes through the 63-62°E longitude. The northernmost record of the species in West Siberia is at 65.55°N.

The Siberian wood frog is listed in the Red Book of Kurgan Oblast (category III, rare species) (Bolshakov et al. 2012), Kemerovo Oblast (category III, rare species) (Skalon 2012), Krasnoyarsk Krai (category III, rare species) (Savchenko 2012), Khanty-Mansi Autonomous Okrug (category III, rare species) (Vasin and Vasina 2013), Yamalo-Nenets Autonomous Okrug (category IV, data deficient) (Ektova and Zamyatin 2010) and Sverdlovsk Oblast (category III, rare species) (Korytin 2018).

Rana arvalis Nilsson, 1842

The moor frog is distributed from Western Europe (Germany, Belgium, Sweden) to East Siberia (Republics of Sakha and Buryatia (Russia)). The southern limit of the range lies in the steppe regions of north Kazakhstan and Mongolia and in the Altai mountains in Russia, north China and Mongolia (Kuzmin 2012). The moor frog inhabits diverse habitats, such as swamps, forests, meadows and river floodplains. In the tundra and in the steppe, the moor frog prefers forested or bush areas in the river valleys, as well as vicinities of other water bodies (Ravkin et al. 2005, Ravkin et al. 2008). It frequently inhabits anthropogenic habitats, including gardens and city parks (Kuzmin 2012).

In West Siberia, the moor frog is the most common amphibian species, which is present throughout the whole studied region, except the furthest north (Yamal and Gyda Peninsulas) and the highest areas of Altai Mountains. The species crosses the Arctic Circle and is distributed up to the Village Tazovskiy (67.47°N; the northernmost record of Amphibia in West Siberia). Here, we report 1137 records of the species.

Due to its abundance, the moor frog is not included in Red Data books in any of the administrative regions of West Siberia.

Rana temporaria Linnaeus, 1758

The common frog is distributed from the Pyrenees to the Urals and West Siberia. The north-eastern border of its range runs from the southern coast of the Barents Sea and the northern coast of the White Sea to southeast and east through the Komi Republic to the Rivers Ob and Irtysh. The south-eastern border of the range is situated in the Kurgan Oblast and north Kazakhstan (Kuzmin 2012). In the northern and southern peripheries of its range, the species is usually found in the vicinity of water bodies (Ravkin et al. 2005, Ravkin et al. 2008).

We report 40 records of this species in West Siberia, from 67.0°N in the north to 55.43°N in the south and to 67.08°E in the east. The eastern border of the range in West Siberia is insufficiently known. In the Yamalo-Nenets Autonomous Okrug, only three populations are known, although there are more finds in the Khanty-Mansi Autonomous Okrug, where the common frog inhabits western and north-western parts of the region.

The common frog is listed in the Red Books of Tyumen and Kurgan Oblasts, Yamalo-Nenets and Khanty-Mansi Autonomous Okrugs as a rare species (category III) (Bolshakov et al. 2012, Vasin and Vasina 2013, Petrova 2020).

Pelophylax ridibundus (Pallas, 1771) complex

The frogs of P. ridibundus complex have a disjunct distribution in West Siberia due to its unintended introduction to some areas. The natural range of this group runs from Eastern Europe to the extreme southwest of Siberia, surrounding the Ural Mountains from the south, since these frogs do not inhabit the forested montane areas of the Urals (Kuzmin 2012, Fominykh et al. 2016).

In West Siberia, the western populations occur in Chelyabinsk Oblast, Sverdlovsk Oblast and Kurgan Oblast. Their origin is debatable and could represent natural range extension in the second half of the 20^th century, spread of invasive populations or combination of both (Fominykh et al. 2016). The eastern, purely invasive populations occur in Omsk Oblast, Tomsk Oblast, Novosibirsk Oblast, Kemerovo Oblast, Altai Krai, Altai Republic, Republic of Khakassia and Krasnoyarsk Krai. The natural sources of introduced populations are hitherto unknown and it is possible that the region is inhabited by several species of the complex and their hybrids. We suppose the presence of P. ridibundus sensu stricto and P. cf. bedriagae, which are widely distributed in the European part of Russia (Litvinchuk et al. 2020). Overall, we report 170 records of Pelophylax ridibundus sensu lato in West Siberia.

Bufo bufo (Linnaeus, 1758)

The common toad is widely distributed in Eurasia, including West and East Siberia. This species mainly inhabits forested areas and prefers swamped conifer forests. It is also encountered in mixed and leaf forests, groves, parks and gardens, where high humidity and dense vegetation are present (Kuzmin 2012). The common toad is less abundant in north taiga than in middle taiga, where it is most numerous in fir, spruce, birch and aspen forests. In south taiga, the toad prefers lowland swamps. In sub-taiga, it is most abundant in swamps and swamped forests, but is also common in drier habitats. In the north forest-steppe, it inhabits birch and aspen forests and forest patches surrounded by agricultural fields. In the south forest-steppe, which is the southern border of its range, the common toad is very rare and inhabits only lowland swamps. This species is not found in the steppes (Ravkin et al. 1998, Ravkin et al. 2003, Ravkin et al. 2005, Ravkin et al. 2008).

We report 539 localities where the common toad occurs. The northern periphery of its range lies between 63.0°N and 64.0°N. The southern range margin in West Siberia is situated in Kurgan Oblast (Yurgamyshskiy and Ketovskiy Districts, at 55.0°N), then it runs through the south of Tyumen Oblast and east of Omsk Oblast to north-eastern Kazakhstan.

The common toad is listed in Red Data Books of Kurgan Oblast (category IV, data deficient) (Bolshakov et al. 2012), Omsk Oblast (category III, rare species) (Sidorov and Plikina 2015) and Yamalo-Nenets Autonomous Okrug (category III, rare) (Ektova and Zamyatin 2010).

Bufotes viridis (Laurenti, 1768)

An isolated, apparently introduced population of green toads occurs in the vicinity of the city of Novosibirsk. In 1984, an established population of green toads already existed near Novosibirsk (Zolotarenko 1985). Genome size analyses of three toads and microsatellite genotyping of one toad from this population suggested that they belong to the species B. sitibundus, the variable toad, which naturally occurs in Eastern Europe east of the Volga River, in the Urals, Caucasus and parts of Central Asia (Litvinchuk et al. 2007). However, a recent analysis of genome size and RAD-Seq genotyping of another sample showed that it belongs to B. viridis sensu stricto, which does not inhabit Central Asia (Dufresnes et al. 2019). Thus, the vicinity of Novosibirsk is apparently inhabited by two species of green toads. More sampling data are required to clarify their distributions and determine the source or sources of the introduction. Near Novosibirsk, the green toads inhabit pine forests (the Novosibirsk Zoo and the park around it), agricultural landscapes with patches of birch forest (near the Village Verkh-Tula) and other habitats.

Bufotes sitibundus (Pallas, 1771)

The variable toad occurs in south-western parts of West Siberia. We report 26 records of this toad in West Siberia, all in the Chelyabinsk and Kurgan Oblasts. The northernmost location is at 56.21°N and the easternmost location lies at 65.45°E. The occurrence of this species is also possible in the Altai Krai, although there is currently no strong evidence for it.

Under the name “Pseudepidalea viridis”, it is listed in the Red Data Book of Kurgan Oblast (category III, rare species) (Bolshakov et al. 2012).

Bufotes pewzowi (Bedriaga, 1898)

Historically, the green toads from the montane regions of the Altai Republic were presumed to belong to B. viridis. In 2010, the analysis of chromosome number and genome size revealed that they belong to the tetraploid species B. pewzowi (Litvinchuk et al. 2010), which is widely distributed in Kazakhstan, Mongolia and China. This was the first report of this species from Russia. In general, there are nine known localities, situated from 51.12°N to 49.65°N and from 500 m a.s.l. to 1700 m a.s.l.

The species is listed in the Red Book of Altai Republic (category III, rare species) (Bondarenko 2017) and in the Red Book of Russia (category 2, EN) (Pavlov 2021).

Pelobates vespertinus (Pallas, 1771)

The Pallas’ spadefoot toad is distributed from Eastern Europe and Caucasus to West Siberia and Kazakhstan (Kuzmin 2012). At the eastern periphery of the range, the spadefoot toad is most numerous in sub-taiga forests, mainly in pine forests on sandy substrates. In the northern forest-steppe zone, the toad mostly occurs in open swamp landscapes. In the southern forest-steppe, it prefers forest patches near fields and meadows. In the steppe, it occurs mainly in halophyte meadows and flood-meadows and, more rarely, in swamp areas around freshwater lakes (Ravkin et al. 2008).

We report 32 records of this species in West Siberia. The north-eastern limit of its range is situated in the Tyumen Oblast (near the City Tobolsk, 58.17°N, 68.33°E).

The spadefoot toad is listed under the name “P. fuscus” in the Red Books of Tyumen and Sverdlovsk Oblasts as a rare species (category III) (Korytin 2018, Petrova 2020).