Abstract
We collected and observed Corbicula samples in the Lake Biwa-Yodo river system and Yamato river system to determine whether invasion of the exotic Corbicula fluminea has occurred. In the Lake Biwa-Yodo river system, C. fluminea has invaded, and the indigenous C. leana has disappeared in the Yodo River. C. fluminea consisted of diploids and triploids. These samples were hermaphrodites and produced non-reductional sperm, suggesting androgenetic reproduction. We could not find C. fluminea in the Yamato river system, and only the indigenous C. leana exists. The present study suggests that the invasion of exotic C. fluminea may result in the extinction of the indigenous C. leana.
