DAO 44:223-230 (2001)  -  doi:10.3354/dao044223

Redescription of Microsporidium takedai (Awakura, 1974) as Kabatana takedai (Awakura, 1974) comb. n.

Jirí Lom1,*, Frank Nilsen2, Shigehiko Urawa3

1Institute of Parasitology, Academy of Sciences of the Czech Republic, Branisovská 31, 370 05 Ceské Budejovice, Czech Republic
2Institute of Marine Research, PO Box 1870, Nordnes gt. 50, A - 5024 Bergen, Norway
3Genetics Section, National Salmon Resources Center, Fisheries Agency of Japan, 2-2 Nakanoshima, Toyohira-ku, Sapporo 062, Japan

ABSTRACT: Ultrastructural study of the microsporidian Microsporidium takedai from the muscles of masu salmon Oncorhynchus masou proved that this species can be assigned to the genus Kabatana Lom, Dyková and Tonguthai, 2000. The parasites develop within disintegrated sarcoplasm without any delimiting boundary or cyst. Cylindrical multinucleate meronts proliferate by serial constrictions into uninucleate stages which repeat the process. Eventually, the uninucleate stages transform into uninucleate sporonts, which divide once to produce sporoblasts, thus functioning as sporoblast mother cells. Spores, with a subterminally located anchoring disc and 3 to 4 turns of the polar tube coil, average 3.3 by 1.9 µm in size. The exospore is divided into small fields; the endospore frequently makes small invaginations into the spore inside. Phylogenetic analysis using SSU rDNA sequence consistently placed Kabatana takedai in a group consisting of Microgemma sp., Spraguea lophii and Glugea americanus. The K. takedai could easily be separated from the other species in the same group by 2 inserts in the SSU rDNA sequence.

KEY WORDS: Microsporidium takedai · Kabatana takedai · Microsporidia · Ultrastructure · SSU rRNA phylogeny · Oncorhynchus mykiss

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