CURRENT DISTRIBUTION OF BULGARICA CANA ( HELD , 1836 ) ( GASTROPODA : CLAUSILIIDAE ) IN EUROPE

The range of Bulgarica cana (Held), up-dated on the basis of recent publications and conchological material collected since 1990, covers the whole of the Carpathians and the eastern parts of the Sudetes; the lowland range extends through eastern Poland, Ukraine, Belarus, Lithuania, Latvia and part of Estonia to Russia in the east. The species’ range, with insular sites on the fringes, is fragmented as a result of the habitat fragmentation.


INTRODUCTION
Bulgarica cana (Held, 1836) is a central and east European species (Kerney et al. 1983).As most clausiliids, it has a sinistral, fusiform shell, with the closing apparatus consisting of a movable clausilium and folds restricting its movement (liKharev 1962(liKharev , nordsiecK 2007)).The shell of B. cana is thickwalled, red-brown in colour, slightly transparent and ribbed; the ribs are slightly sinuous, often grey or whitish (Fig. 1).The aperture is elongated, diamondor egg-shaped with a broad white lip.The dorsal keel, and the superior and inferior lamellae are clearly visible trough the aperture.The inferior lamella is often light-red in colour and never bifurcated.The shell height is 14-19 mm, the width 3.3-3.9mm; the number of whorls is 11-14 (Urbański 1957, liKharev 1962, Kerney et al. 1983, wiKtor 2004, welter-schultes 2012).
B. cana inhabits moist deciduous and mixed forests in the mountains and foothills, and is less frequent in lowland forests (liKharev 1962, Kerney et al. 1983, horsáK et al. 2013), with strong preference for well-preserved and undisturbed tree stands.It is a strictly dendrophilous species, living on trunks and in bark crevices of live or dead, standing or fallen trees, and less frequently found in litter (liKharev 1962, Kerney et al. 1983, sUlikowska-DrozD 2005, horsáK et al. 2013).
As a result of fragmentation of its preferred habitats, the species' range is fragmented, with some

SPECIES RANGE PRIOR TO 1990
A precisely reconstructed distribution of B. cana in the middle of the 20th century (Figs 2-3) was adopted as the starting point to determine the species' current range.The distribution range in eastern and south-eastern Europe (Fig. 2, liKharev 1962, current country names are given) covered the whole of Carpathians to the northern Balkans in Bulgaria; Poland; the Baltic countries except western Estonia.In Russia, there was a number of sites in the Moscow district and in the western part of St. Petersburg district.There were single sites near Pskov, Smolensk, Roslav, Bryansk and Kazan, and in the districts of Orlov, Tula and Belgorod.In Belarus, there were single sites near Vitebsk and the Pinsk marshes; in Ukraine the species was recorded from the Carpathians and from the environs of Kiev.In central and western Europe (Fig. 3, Kerney et al. 1983) the range of B. cana included the northern foothills of the Alps from Lake Constance in northern Switzerland to south-eastern Bavaria (Germany); in Germany also single sites in the mountains in the southern and central parts of the country and on the Baltic coast; western and northern Austria; in the Czech Republic and Slovakia the Carpathians and the Sudetes, otherwise rather rare; Poland and one locality in Finland (Koli).Most of the data from conchological collections (collected prior to 1990) overlap the range presented above (Fig. 4).The biggest discrepancy is the presence (on the map in Fig. 4) of numerous sites in the mountains of the Black Forest, Baden-Württemberg, Germany (collections from the first half of the 20th century).There are also other single sites at the edge of the range.

SPECIES RANGE AFTER 1990
Comparison of the new data (collections and publications since 1990) with those listed above presents a strikingly different picture.Most of the ranges also overlap; however, there are many discrepancies.While the new sites can be easily interpreted as an increase in the knowledge about the previously less studied areas, the absence of sites presents more difficulties.The lack of data may be caused by a simple lack of research.Also the absence of the species in the studies is difficult to interpret; it does not necessarily mean that the species was not present.
Both historically and currently, the core of the range of B. cana is primarily the Carpathians which hold most numerous records over the past 25 years.The species inhabits the entire mountain range from Romania (Domokos & Váncsa 2005, sólyMos & Páll-GerGely 2007, gheoca et al. 2008), through Ukraine (pelbárt 2000, Khlus & sverlova 2004, baiDashnikoV 2005, gural-sverlova & gural 2009), Poland (szybiaK 2000, suliKowsKa-drozd 2005, caMeron et al. 2010, alexandrowicz 2011, zając 2014), Slovakia (ŠteffeK 2000, jUřičkoVá et al. 2005b) and Hungary (bába & tóth 2000, deli 2002, sólyMos et al. 2009) to the Czech Republic (horsáK 2003, 2005, horsáK et al. 2006).In the Czech Republic, the species is more common in Moravia.Besides numerous Carpathian populations, there are also sites in the Sudetes (jUřičkoVá et al. 2005a, lacina 2010)   It is difficult to ascertain the range of B. cana in Poland (Fig. 5).Until recently it was assumed that the species inhabited the entire country (liKharev 1962, Kerney et al. 1983Kerney et al. , welter-schultes 2012)).However, riedel (1988)  The knowledge of the occurrence of B. cana in the Baltic countries is incomplete.There is no information on terrestrial snails in the Kaliningrad District.However, the presence of B. cana at numerous sites in the Polish part of Romincka Forest suggests that the species is also present on the Russian side.B. cana is known to occur in Lithuania (sKuJiené 2002), but there are no detailed data on its distribution.In Latvia the species occurs in many parts of the country, but everywhere it is rare and not abundant (Pilāte & greKe 2002, Pilāte 2003).There is no information on its occurrence in Estonia.
B. cana is moderately abundant in Belarus (zeMoglyadchuK 2009).It probably does not occur in the central part of the country (Fig. 5), where it has never been found before (liKharev 1962).Currently, most of its sites are located in northern and north-eastern Belarus, in the region of Vitebsk (MerzhvinsKii 2011, Kotsur 2015).The occurrence of B. cana in the south, in the Pripyat valley near the border with Ukraine, is also likely, because of the earlier records (liKharev 1962); it is still found on the Ukrainian side (baiDashnikoV 2005, balashov 2012).The species may also occur in the west of the country.The presence of B. cana in the Polish part of Białowieża Forest may suggest that it is also present on the Belarusian side.
The south-eastern boundary of the range of B. cana runs through Ukraine (balashov 2016) and is conventionally thought to follow the southern borders of the Vinnitsa, Kirovograd, Poltava and Sumy districts (Fig. 5).The species is present in many sites throughout western and northern Ukraine from the Carpathians to the boundary with Russia (pelbárt 2000, Khlus & sverlova 2004, baiDashnikoV 2005, balashov 2010, 2012, 2016, gural-sverlova & gural 2009, 2010, 2011, balashov et al. 2013).In many regions, however, it is rare, and its presence at the fringes of its range depends on a large amount of dead timber at the sites (balashov 2016).In Lviv, Ukraine, the only record of B. cana so far known is from a forest-like city park (gural-sverlova 2014).
The B. cana has also a number of widely scattered insular records rather remote from the continuous range.In the west, there are sites in Germany, formerly numerous in the German highlands and now decreasing in number.Nowadays the species is still present in the forests of Thuringia (reuM 2006) and in the south in the mountains of the Black Forest.The re-finding of B. cana in the forests of Lower Saxony, where it was not found for years (lill 2004), suggests that the species may have survived in many other former sites.Currently there are no data on the species' occurrence in the lowland parts of Germany.
Likewise, there is no new information on the presence of B. cana in Austria and Switzerland.
Isolated populations of B. cana exist in northern Europe, in Sweden and Finland (Fig. 5).In Sweden, there are several sites.The northernmost record, near lake Vättern, is recent (fritz & von proschwitz 2000).In Finland only a single site, in the Koli National Park, is known (rassi et al. 2010).
The single site in Moldova (baiDashnikoV 2005, balashov et al. 2013), in the Codru Reserve, located in the centre of the country, can be treated as an insular site outside the range but also as a connection between the Romanian (Carpathian) and western Ukrainian sites which makes it possible to define the south-eastern range limit (Fig. 5).Because of the small forest cover of Moldova, as well as the lack of data (contemporary or historical) on the occurrence of B. cana in eastern Romania outside the Carpathians, I decided to treat the Moldovan site as insular.
B. cana does not occur in Bulgaria (dedov 1998, irikoV & erőss 2008).Earlier records may have been based on misidentification.In Bulgaria Bulgarica is represented by a total of 10 species, some of them with several subspecies (irikoV & erőss 2008).Though many of these taxa do not deserve species status (welter-schultes 2012), it shows the great diversity and richness of the genus in Bulgaria.
Comparison of the maps (Figs 4-5) gives a false impression of an eastward range expansion.Most of the new malaco-faunistic research was carried out in central and eastern Europe, hence so many new records from this region.This does not mean, however, that the sites of B. cana are new.On the opposite, western, edge of the range the 'loss' of sites may have many reasons.First, the species may have never occurred in some areas, but its range was misinterpreted on the maps; for example, according to Kerney et al. (1983) B. cana is present in the Czech Republic in the Carpathians and in the Sudetes, otherwise rather rare; this statement is not reflected on the map, where its range covers all of the Czech Republic.It is also not excluded that some of the records of B. cana in western Europe resulted from misidentification.The species is sometimes confused with Balea biplicata (Montagu, 1803), a common and euryoecious western European species.An actual shrinkage of the range is also very likely; however, it is difficult to determine if there are areas where the species has become extinct, and where they are.B. cana occurs 2006, red data booK of estonia 2008).In Latvia it has category 'rare' (spuris 1998).Nowadays forest management, especially the removal of dead timber, is responsible for the increasingly endangered status of B. cana (lill 2004, balashov 2016).
It is possible that in many countries, especially in western Europe, at present there is less field research compared to the past.The lack of new data may be caused by the lack of research or experts.It is very likely that B. cana is still present in those well-preserved forests in Germany, Switzerland and Austria for which faunistic information was published long ago.

CONCLUSION
Based on the above data, the range of B. cana is as follows (Fig. 5): the whole of the Carpathians and eastern parts of the Sudetes; with the lowland part of the range extending through eastern Poland, Ukraine, Belarus, Lithuania, Latvia, part of Estonia, to Russia in the east.Many insular sites are scattered on the fringes of the range: in the west in Poland, western Bohemia, central and southern Germany; in the north in Sweden and Finland and in the east in the Volga Basin in Russia.
The distribution of B. cana presented here is rather generalised and simplified.The species is closely associated with natural forests.Since they are not continuous over large areas, the species' range is disjunct and in places even insular.

Fig. 4 .
Fig. 4. Distribution of Bulgarica cana with locality data added, range according to liKharev (1962) and Kerney et al. (1983) is shown in the background remarked that there were no records of B. cana from Mazovia (except one sub-fossil site in Kampinos Forest) and in Podlasie (except Białowieża Forest).The species was also missing in potentially suitable habitats in central Poland, as well as throughout the lowlands west of the Vistula, for example in the environs of Łódź (suliKowsKadrozd 2010), in Kaszuby (caMeron & poKryszKo 2006) or in many parts of Wielkopolska (szybiaK 2002, KoralewsKa-batura et al. 2006).The only sites in this part of the country are single records from the Drawa National Park in the South Pomeranian Lakeland (szybiaK et al. 2005) and in Wielkopolska (szybiaK 2008, JanKowiaK pers.com.).In recent years there were no records of B. cana either from potentially attractive forest stands in the mountains and uplands (caMeron et al. 2010), i.e. in the Kraków-Częstochowa Upland in the vicinity of Ojców, in the Świętokrzyskie Mts, or in the Polish part of the Sudetes, although it is still present in the eastern Sudetes in the Czech Republic (jUřičkoVá et al. 2005a, lacina 2010).The situation in the eastern part of Poland looks different.The species' range extends from Romincka Forest and its adjacent areas in the north (caMeron et al. 2010, Marzec 2010), through Augustów Forest (caMeron et al. 2010), Białowieża Forest (caMeron & poKryszKo 2004), Polesie and Roztocze (caMeron et al. 2010) up to numerous sites in the Carpathian Region.Since there is no information on the malacofauna of large forest complexes in the Mazurian Lakeland, such as Pisz Forest, Borecka Forest and Napiwodzko-Ramucka Forest, fragments of which may offer suitable habitats, the region cannot be excluded from the range of B. cana.
eastern limit of the range is difficult to ascertain.The current information on the occurrence of B. cana in Russia is insufficient.Only sites in the district of Tula were confirmed recently (MaMatKulov 2005).The historic records along the western borders of Russia with Ukraine, Belarus, Latvia and Estonia, as well as the sites near Moscow and St. Petersburg (probably best known because of the proximity of academic centres) (liKharev 1962) allow a delineation of an approximate boundary.The easternmost sites of the species are found in the Volga valley and its tributaries: in the vicinity of Kazan (liKharev 1962) and in the Vyatka basin (shiKhova 2007), or more to the southwest in the environs of Penza (bulavKina & stoyko 2007, 2008, stoyKo et al. 2008).The localities of B. cana on the far eastern edge of Europe should be regarded as insular, outside the continuous range.

Fig. 5 .
Fig. 5. Up-dated distribution of Bulgarica cana Names of localities given as on original labels.Collections: DU & NHML -Daugavpils University and Natural History Museum of Latvia; FMNH -Finnish Museum of Natural History; HNHM -Hungarian Natural History Museum; MIZ -Museum and Institute of Zoology, Poland; MP -Museum of Natural History, University of Wroclaw, Poland; NHMW -Natural History Museum, Vienna, Austria; NNHM -Natural History Museum, Oslo, Norway; PhM -Phyletisches Museum, Jena, Germany; SMNH -Swedish Museum of Natural History; SNM -Slovak National Museum.ASD -anna suliKowsKa-drozd; DvK -dietrich von Knorre; GS -grita sKuJiené; MH -Michal horsáK; MM -Magdalena Marzec; RADC -robert caMeron Slovak National Museum.I also used my own private collection as well as those made available by robert caMeron, Michal horsáK, dietrich von Knorre, grita sKuJiené and anna suliKowsKadrozd.Altogether 306 samples (1,874 shells) were analysed (Appendix 1).The recent literature on the occurrence of B. cana and forest snail communities was also reviewed.Data collected prior to 1990 were regarded as historic, those collected since 1990 as current.
Conchological material examined, with notes on physiographic regions of Europe.