Life histories of three Serrulinini species (Stylommatophora: Clausiliidae) from Georgia kept under laboratory conditions

Abstract

The Serrulinini, a small relict group of clausiliids occurring in coastal regions of the Black and Caspian Seas and the Caucasus, are currently classified within the Phaedusinae, however paraphyletic origin of the Serrulinini is also widely debated with Pontophaedusa funiculum (Mousson) being most phylogenetically distinct from other taxa. As life history data may have taxonomical value, we conducted long-term observations in laboratory culture to assess reproductive modes, fecundity and growth pattern of three serruline species. Caspiophaedusa perlucens (O. Boettger) and Pravispira semilamellata (Mousson) produced partly calcified eggs with regular, spiral arrangement of crystals; their juveniles hatched after 17–18 days; the generation time was long and significantly exceeded one year. P. funiculum laid heavily calcified, elongated eggs. The incubation time in P. funiculum varied depending on the humidity, with a tendency towards short embryo-retention. The generation time in P. funiculum was one year. In all the studied species, egg calcification differed from the pattern common for other oviparous Phaedusinae which produce partly calcified eggs with homogeneous distribution of crystals. The calcite crystal distribution in the egg membranes reported here for the Serrulinini suggests some potential of these characters in phylogenetic context.