Contribution to the biology of ten vertiginid species

Laboratory and field observations on Vertigo angustior Jeffreys, V. antivertigo (Draparnaud), V. moulinsiana (Dupuy), V. pusilla O. F. Müller, V. pygmaea (Draparnaud), V. ronnebyensis (Westerlund), V. substriata (Jeffreys), Truncatellina cylindrica (Férussac), Columella aspera Waldén and C. edentula (Draparnaud) provided new information on their life cycle. Genus Vertigo: the life span is 1–3 years, with most snails dying in the next year after hatching. The reproductive season lasts from half of May till the beginning of September; depending on the life span eggs are laid during 1–3 seasons. The number of eggs per lifetime varies widely, the maximum numbers are 55–79 in V. moulinsiana, pygmaea and ronnebyensis, 102–120 in V. angustior, pusilla and substriata and 218 in V. antivertigo. Most eggs are laid at the stage of one cell (even oocyte II), but in some the advancement of development indicates retention of 1–3 days. Hatching usually starts in the second half of June and lasts till the second half of September. Only some of the snails reach maturity in the year of hatching, usually after the reproductive season. Genus Truncatellina: in the wild the life span of most individuals is about one year, some live till the age of about two years. Eggs are laid from half of June till the end of August (in laboratory maximum 11 eggs); hatching takes place from July till the end of September. Genus Columella: in the laboratory C. aspera lays eggs from half of May till the beginning of September (maximum 5 eggs); hatching starts at half of June and continues till the end of September. C. edentula in the laboratory lays eggs at half of April, and juveniles hatch at the end of May and beginning of June.