The Palearctic oystercatcher Haematopus ostralegus, a natural definitive host for Gymnophalloides seoi

In order to verify the role of migrating birds as natural definitive hosts for Gymnophalloides seoi (Gymnophallidae), Palearctic oystercatchers, Haema topus ostralegus. were caught from several western coastal areas in the Rep ublic of Korea and examined for intestinal flukes. Five (71.4%) of 7 oyster catchers were infected with 302-1,660 (mean 892) adult G. seoi. In intestin al sections of the host, worms were found in the intervillous space of the mucosal layer. We conclude that the oystercatcher is a natural definitive h ost for G. seoi.