First record of Perkinsus olseni in cultured mussels (Mytilus chilensis) in the Beagle Channel, Southwestern Atlantic Ocean

Abstract

During the field survey for the mussel Mytilus chilensis from Bahía Brown (54°47′S, 68°14′W) of Beagle Channel, Argentina, infection of a Perkinsus-like protozoan parasite was histologically detected. These parasite cells were found in connective tissue of the digestive gland, in gill filaments, gonad and muscle, and often host responses such as strong hemocytic infiltration and granulomas were observed. Histological analysis showed the presence of trophozoites and tomonts of Perkinsus sp. The identity of the parasite was determined by a species-specific PCR assay in rDNA samples obtained from the infected mussels. Sequencing of amplified fragments ITS1-5.8S-ITS2 showed 100% identity to Perkinsus olseni. We present the first record on the occurrence in the Argentinean Sea waters of the protozoan parasite P. olseni infecting the mussel M. chilensis from culture populations. At date, it represents the southernmost distribution range of this parasite.