EN
Helix lutescens Rossmässler, 1837 is a xerothermophilous species. It reaches its NW distribution border in SE Poland. The studies, carried out in 1990–1997, involved the distribution of H. lutescens in Poland, its biology and ecology. Besides, shell structure and internal organs were studied, with special reference to differences between H. lutescens and the related H. pomatia L. In H. lutescens the shell is roundish-conical, of a yellowish- white colour and much smaller than that of H. pomatia. The body is greyish and covered with numerous wrinkles and grooves; fine, whitish granules are located in the grooves, especially in those that form two delicate light streaks along the darker back of the animal; these streaks are characteristic of the species. The reproductive system of H. lutescens is of a structure similar to that in H. pomatia, but the duct of the gametolythic gland never bears a diverticle while flagellum, epiphallus and penis in adults are pigmented. The diurnal activity of H. lutescens varies seasonally, depending on environmental factors (air temperature and relative humidity in ground layer, and substratum humidity – dew point). The reproductive activity reaches its peak in May and June. Courtship and copulation are in accordance with the typical helicid pattern. The copulation lasts ca. 15 mins, and the entire mating process takes over 3 hrs. Eggs are laid in nests dug in the soil, the mean number of eggs per nest being 35. In two weeks young hatch and remain in the nest for ca. 16 days. The abundance and density of three age classes in a selected population of H. lutescens have been estimated on a permanent sampling plot, using marking-release-recapture method, with JOLLY-SEBER‘S model for an open population. The results made it possible to trace seasonal changes in the abundance within the whole population. In Poland H. lutescens, because of its insular occurrence and the threat resulting from confusion with the edible H. pomatia, is a protected species.