DAO 48:133-142 (2002)  -  doi:10.3354/dao048133

Ovipleistophora gen. n., a new genus for Pleistophora mirandellae-like microsporidia

M. Pekkarinen1,*, J. Lom2, F. Nilsen3

1Division of Animal Physiology, Department of Biosciences, PO Box 17, 00014 University of Helsinki, Finland
2Institute of Parasitology, Academy of Sciences of the Czech Republic, Branisovská 31, 370 05 Ceské Budejovice, Czech Republic
3Institute of Marine Research, Department of Aquaculture, PO Box 1870, 5817 Bergen-Nordnes, Norway

ABSTRACT: Based on ultrastructural study and molecular analysis, a new genus, Ovipleistophora, is established for Pleistophora mirandellae-like microsporidia from roach and ruff oocytes. Unlike Pleistophora, Ovipleistophora has a thick additional envelope around the meront. This envelope breaks open to release the cells into the host cell cytoplasm. The cells, becoming multinuclear sporogonic plasmodia, already have a surface coat that transforms into the sporont wall and eventually into the sporophorous vesicle wall. The surface coat and its transformation differ from those of Pleistophora, but bear some resemblance to those of Trachipleistophora. In Trachipleistophora the sporonts, however, do not form plasmodia, as they do in Ovipleistophora and Pleistophora. Small subunit ribosomal DNA analysis supports the establishment of the new genus and assignment of P. mirandellae from 2 different fish hosts to the same species. The same small subunit ribosomal DNA analysis lends support for transferring P. ovariae into the genus Ovipleistophora.

KEY WORDS: Pleistophora · Ovipleistophora · Microsporidian ultrastructure · Rutilus rutilus oocytes · Gymnocephalus cernuus oocytes · Molecular phylogeny

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