偶発的移入種オオクビキレガイ(腹足綱:オカクチキレガイ科)の福岡県での生息状況とその拡散速度

概要

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In Japan, Rumina decollata (Linne, 1758) was first reported at Tobata-ku, Kitakyushu City, northern Kyushu in 1988. The species was subsequently found at various localities in western Japan, including Ube in Yamaguchi Prefecture (1992), Fukuma-machi in Fukuoka Prefecture (1998) and Shirahama in Wakayama Prefecture (2002). In 2004, living examples of this species were found in Koga City and Fukuoka City, both in Fukuoka Prefecture. Until the middle of December, the animals actively fed on lettuce and other vegetables in a kitchen garden at night. Observations of the animals in a container showed that they spent both day and night in sand between the end of December and the middle of March. Around the end of March and the beginning of April the animals started to feed on vegetables actively. They copulated on 31 March 2005 and 6 April 2005 and laid eggs in the ground. The eggs hatched on 12 and 18-20 May 2005. The animals also laid eggs in October. A dispersion coefficient is estimated based on the distance between Tobata, where R. decollata was first found, and various localities in Fukuoka Prefecture, and on the number of years R. decollata needed to arrive at each locality in Fukuoka Prefecture. The dispersion coefficient in Fukuoka Prefecture is about 3km/year or more. The correlation coefficient between the distance and the time is 0.74, which suggests that the species disperses gradually day by day.
日本貝類学会の論文
2006-03-31