Morphological and Molecular Confirmation of Parvatrema duboisi Metacercariae in the Manila Clam Ruditapes philippinarum from Gochang-gun, Korea

Abstract

Gymnophallid metacercariae found in the Manila clam <i>Ruditapes philippinarum</i> (‘Banjirak’ in Korean) from Gochang-gun, Jeollabuk-do, Korea were morphologically and molecularly confirmed to be <i>Parvatrema duboisi</i> (Dollfus, 1923) Bartoli, 1974. The metacercariae were morphologically characterized by having a large oral sucker, small ventral sucker, genital pore some distance anterior to the ventral sucker, no ventral pit, and 1 compact or slightly lobed vitellarium, which were all compatible with <i>P. duboisi</i>. Some of the metacercariae were experimentally fed to mice, and adult flukes were recovered at day 7 post-infection. The morphology of the adult flukes was basically the same as that of the metacercariae except for the presence of uterine eggs; the uterus was filled with up to 40 eggs. The nucleotide sequences (1,193 bp) from ITS regions (ITS1, 5.8S rDNA, and ITS2) of the metacercariae showed 99.7% identity with <i>P. duboisi</i> and 75.7% identity with <i>Gymnophalloides seoi</i> deposited in GenBank. These results confirmed the presence of <i>P. duboisi</i> metacercariae in the Manila clam <i>R. philippinarum</i> in an estuary region of Gochang-gun, Korea.