Infection of Japanese Eel Anguilla japonica Elvers by Hemiclepsis marginata (Hirudinida: Glossiphoniidae)

Elvers of the Japanese eel Anguilla japonica Temminck and Schlegel (Anguilliformes: Anguillidae) collected at the mouth of a small river on the Pacific coast of central Japan were found infected by the glossiphoniid leech Hemiclepsis marginata (O. F. Müller, 1774)(prevalence 3.3%, intensity 1). This finding represents the first and second cases of infection of A. japonica by H. marginata and by leeches in Japan, respectively, and suggests that the infection by H. marginata occurred in brackish waters. The external morphology of H. marginata is briefly described. Anguilla japonica is a new host for H. marginata.