World Congress of Malacology Antwerp ... - Unitas Malacologica

fundamental paper by Solem and Yochelson (1979) on North American Palaeozoic snails; the
authors, however, did not attempt identification of these forms.
Recently, a rich malacofauna has been found again in the swamp facies of Lower Permian molasse
deposits of postvariscan, rift valley, situated NE from Cracow, which comprise volcanic rocks,
fanglomerates, playa mudflat deposits and freshwater carbonates mostly referred to as Karniowice
Travertine. In fact these carbonate rocks encompass, beside the travertines, also other calcareous
deposits such as limnic varved limestones, fluvial carbonates, and calcareous deposits of swamp
facies (palustrine carbonates), with numerous, calcified remains of vascular plants. These plants
allowed to determine their habitat as topogenous fen. The rich assemblage of hygrophilic plants
under generally semi-arid climate conditions of the Lower Permian was possible only due to the
presence of a vast system of karstic springs which fed an extensive oasis.
Contrary to the Early Permian malacofauna from the so called ”Karniowice tufa” which has been
mentioned in the world literature, there are no published data on snail remains found in Upper
Carboniferous sphero-siderite concretions in spoil-heaps of the mine in Sosnowiec (Upper Silesia
Coal Basin). A preliminary assessment indicates that they represent at least two snail species. Earlier
findings from the site including representatives of freshwater and terrestrial fauna: crustaceans,
bivalves, insects and remains of terrestrial plant of the genera Calamites, Sigillaria and Lepidostrobus
were published some years ago.
Life history and population dynamics of Vestia gulo (E.A. Bielz, 1859) (Pulmonata:
Clausiliidae)
Sulikowska-Drozd, Anna
Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237
Lodz, Poland,
Email: sulik@biol.uni.lodz.pl
Life cycle of forest dwelling clausiliid Vestia gulo was studied in the field and in laboratory. Field
data were collected in the Polish Carpathians in four localities that represent different habitat
conditions within the whole altitudinal range of the species. Seasonal changes in the age structure of
population and whorl increment in marked individuals has been investigated.
Vestia gulo is oviparous but able to egg retention. In natural populations, from May till July, a high
proportion of adult snails contain eggs (8 – 21) in the reproductive tract. Egg laying starts in June and
reaches maximum in July. In laboratory, V. gulo lays eggs in 1-3 batches per year, mainly in April
and May, during five seasons at least. Clutch size ranges from 6 to 19 eggs. Hatching is
asynchronous. Egg cannibalism within clutch occurs on regular basis. Shell growth is completed after
10-12 months while egg laying starts not earlier than 24 months from hatching. Directly after
formation of closing apparatus the reproductive system is immature. V. gulo is able to reproduce
uniparentally however hatching success in individuals kept in isolation is low.
In the populations inhabiting mountain foothills ( 425 m above sea level) young snails reach about
6,5 whorls in the first growing season while not more than 5 whorls in the population from the upper
mountain zone (1150 m a.s.l.). In the second season young snails inhabiting foothills reach ultimate
size and those from the higher altitudes reach 8 whorls and overwinter for second time before
completing growth. Consequently, the time required to accomplish growth increases with altitude
from 10 months to over 2 years, even if the adult size decreases from 10,7 to 9,4 whorls along the
same gradient.
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