Studies on Intraspecific Variation in a Land Snail, Satsuma tanegashimae (Pilsbry) (Stylommatophora; Camaenidae) II : Variation of Genital System Structure

Abstract

Genital system was studied for intraspecific varaition in a camaenid land snail, Satsuma tanegashimae (Pilsbry, 1901), which is distributed in the northern parts of the Ryukyu Islands. In the genus Satsuma the genital system is in structure rather stable. Some characters such as the shape of appendix of epiphallus and flagellum, however, vary among populations of the same species or even between individuals of the same population, so that they cannot always be used in discriminating between species. Interpopulational variation of genital system is not great in S. tanegashimae, which is constantly distinguished by a very long flagellum from its congeners. The Uji population has a somewhat peculiar genital system with a long appendix of epiphallus and small bursa copulatrix sac. The Kusagaki population has small genitalia for its large shell. Discriminant analysis was made to estimate the distances (Maharanobis D-square : MD) between populations based on genital system characters. Cluster analysis using MD-values suggested that three groups (Uji, Kusagaki-Mishima-Tokara, and Tane-Yaku) exist within this species, and that the Uji population is quite peculiar. The Kusagaki population may have been derived from a stock on the Tokara Islands.