NEW RECORDS OF PUPILLA PRATENSIS ( CLESSIN , 1871 ) IN WESTERN POLAND

Two localities of Pupilla pratensis were found in the environs of Gubin and Stêszew, W. Poland. Only one recent record of the species, earlier regarded as an ecotype of the widespread P. muscorum, was known from Poland. Consequently, the distribution and conservation status of the species are not well known. Our data indicate that P. pratensis is rare and has specific habitat requirements. In our study area it was found in only two out of 71 examined localities of a very similar habitat type and sampled on the same occasions. The two localities are wet meadows covered by sedges (mostly Carex acutiforis) growing on a calcareous peat substratum of lacustrine origin; the species is accompanied by two rare and legally protected vertiginids: Vertigo angustior and V. moulinsiana.


INTRODUCTION
Pupilla pratensis (Clessin, 1871) is a small pulmonate land snail with a tall, cylindrical, brown shell (VON PROSCHWITZ et al. 2009, HORSÁK et al. 2010) (Fig. 1).For a long time the species was regarded as an ecotype of a very similar and widespread P. muscorum (Linnaeus, 1758).Its taxonomic identity was confirmed by VON PROSCHWITZ et al. (2009) as a result of comparative analyses of morphological, ecological and molecular traits.Most probably P. pratensis was reported from some localities as P. muscorum, and its current distribution and conservation status are unknown.Only recently the species was included in the red list of molluscs in Germany (JUNGBLUTH et al. 2009) with "Gefährdungskategorie R" category (extremely rare).
According to the present knowledge, these two species differ distinctly in their habitat requirements.P. muscorum is considered to be xerophilous and inhabits dry, insolated and calcareous substrata (WIKTOR 2004) whereas P. pratensis is a hygrophile.In central Europe and Scandinavia the species inhabits treeless, often calcareous wetland habitats (CLESSIN 1871, JUEG 1997, ZETTLER et al. 2006, V O N PROSCHWITZ et al. 2009, VON PROSCHWITZ 2010, HORSÁK et al. 2010, 2012).Only in Northland County of Norway it was found on calcareous, rocky slopes close to the sea (VON PROSCHWITZ 2010).
The conchological differences between P. pratensis and P. muscorum include the size of the shell, its colour and morphology of the body whorl (Figs 1, 2).The shell of P. pratensis is usually darker, larger and with more numerous whorls than that of P. muscorum.Also the lip as well as teeth are less developed in P. pratensis (VON PROSCHWITZ et al. 2009).
There are only two previous records of P. pratensis from Poland: one by GOLDFUSS (1883) from Upper Silesia, another made almost 180 years later by HORSÁK et al. (2012) from north-eastern Poland, near the border with Lithuania.In this paper we report on two more localities of P. pratensis in western Poland: Wielkopolska and Ziemia Lubuska regions.

MATERIAL AND METHODS
In 2011 and 2012 we surveyed a total of 71 wetland localities in western Poland: 39 near Gubin (Ziemia Lubuska region) and 32 in the Wielkopolski National Park (Wielkopolska region) which is ca.120 km away.Potential habitats selected based on maps, orthophotomaps as well as available botanical data included treeless or semi-open, wetland areas, covered by monocotyledon plants (sedges mainly).Each locality was searched for molluscs by the two authors for 30 minutes (total: 60 minutes).We examined leaves and stems of plants, we also searched and sieved the litter using 0.5 mm sieve and checking briefly the separated particles on a white tray for the smallest gastropods.Most snails were identified in situ using magnifying glass, only doubtful snails were checked in the laboratory under the stereomicroscope.The species were identified following descriptions by HORSÁK et al. (2010).

RESULTS
P. pratensis was found only in two out of the surveyed 71 potentially suitable sites.One was located near the city of Gubin, Ziemia Lubuska province, about 4 km from the Polish-German border (Fig. 3), the other was near Stêszew, Wielkopolska province, within the Wielkopolski National Park (Fig. 4).The aerial distance between the localities is 131 km.

SITES DESCRIPTION
1. Coordinates: 52°3'06''N, 14°48'20''E The locality of P. pratensis in Ziemia Lubuska, Krzesiñski Landscape Park (Figs 3,5), had an area of ca.2.5 ha and was a part of a complex of meadows extensively used in the past, covering ca. 8 ha, partially waterlogged and covered by reed (Phragmites australis).The site where the species was found was covered mainly by sedges (Carex acutiformis) and crossed by ditches which stretched between lakes Borek, Bagniste and G³êbno, and connected with the £omianka stream.The litter layer was well-developed and saturated with water.The locality was bordered by a pine forest on its western and south-eastern side and by ditches on its north-eastern side.Numerous water--filled depressions were present within the area.P. pratensis inhabited the wet litter and was accompanied by other hygrophilous snails such as Vertigo angustior and V. moulinsiana (Table 1).

Coordinates: 52°18'15''N, 16°41'03''E
The species was widely distributed over an area of 7.5 hectares in the eastern part of a complex of mead- ows and wetlands covering ca.95 ha, bordering with the Trzcieliñskie Bagna Reserve (Fig. 4).Carex acutiformis was the dominant plant, only some waterlogged parts were vegetated by Phragmites australis.
The locality was crossed by numerous ditches connected with the Samica Stêszewska River and Lake Trzcieliñskie.The site was extensively mown, only its fragments next to the ditches were intact and sedge-covered (Fig. 6).The site is protected as a part of the Wielkopolski National Park as well as the Natura2000 network area (Ostoja Wielkopolska, PLH300010).Live individuals of P. pratensis were found in the litter layer in both mown and intact vegetation patches.The number of snail species occurring at this locality was much smaller than that recorded near Gubin (Table 1).In the unmown patches the litter layer was well-developed and P. pratensis was accompanied by V. angustior, V. moulinsiana and Arion intermedius.The mown patches held little litter and the species co-occurred with V. angustior only.HORSÁK et al. 2010HORSÁK et al. , 2012)).The site description however seems to be incomplete, since the species occurred only in less than 3% of the examined potentially suitable sites.Unique microhabitat characteristics, hydrology or site history may be the factors limiting its occurrence.2. P. pratensis was found only in damp litter.The species probably feeds on dead plants remaining on the soil or on microorganisms developing in the detritus (STEUSLOFF 1937).3. The species was found only in two localities out of the total of 71 explored, which makes P. pratensis rare in the studied areas.More detailed studies are necessary to assess its occurrence and conservation status.
4. In both sites the species co-occurred with two rare and threatened snails: Vertigo angustior and V. moulinsiana.However, P. pratensis was less frequent than the two vertiginids (KSI¥¯KIEWICZ & GO£DYN in prep.), and thus its conservation status could be even higher.5. Due to the rather recent distinction between P.
pratensis and P. muscorum and to the small number of records of the species in Poland, there is an urgent need for re-examining snail collections for Pupilla pratensis and for studying its distribution to determine the conservation status.