DIFFERENCES IN THE LIFE HISTORIES OF XEROLENTA OBVIA (MENKE, 1828) (HYGROMIIDAE) IN A COASTAL AND A MOUNTAINOUS AREA OF NORTHERN GREECE

The life cycle of Xerolenta obvia (Menke, 1828) was studiedin two areas, Paleokastro (Chalkidiki), an inland mountainousarea, and Nea Karvali (Kavala), a coastal area in northern Greece.At Paleokastro snails hatch in autumn, become adult the followingJuly, but do not lay eggs until October, after which they die.Clutch sizes are small, but eggs and hatchlings are large comparedwith those at Nea Karvali. Growth is fast in spring, and continuesuntil the end of July. The young hatchlings have dark shell-bands,but by July a quarter of snails appear unbanded. At Nea Karvali,eggs are also laid in October, and young snails emerge fromhibernation in March. Here, however, they do not mature untilApril of the following year. They thus have a 2-year life cycle,with adults dying in their second autumn. Clutches are aboutthree times the size of those at Paleokastro, but eggs and hatchlingsare significantly smaller. A little growth occurs in winter,but the rate of growth is generally much slower than at Paleokastro.Only 1–2% of this population has banded shells; the bandsare less obvious and they become invisible in some individualsas they mature. At both sites population density fluctuatedduring the two study years, but it was always higher at NeaKarvali. These results are discussed in relation to the differingclimates of the sites, and comparisons made with studies onrelated species in the region. (Received 23 July 2004; accepted 30 December 2004)