ULTRASTRUCTURAL-STUDY OF NOSEMA-OMANIAE SP-N (MICROSPORA, NOSEMATIDAE) PARASITE OF OMANIA-COLEOPTRATA (HETEROPTERA, OMANIIDAE)

Nosema omaniae (Microsporida, Nosematidae) is being described from Oma nia coleoptrata (Heteroptera, Omaniidae). The microsporidium attacks t he adipose and nervous tissues and the muscles. All developmental stag es are in direct contact with host cells cytoplasm and their nuclei ar e diplokaryotic. The meronts are bounded by a thin electron-dense wall and their cytoplasm contains some free ribosomes. The sporonts posses s a thick electron-dense envelope and a cytoplasm with abundant riboso mes. The sporoblasts transform directly into diplokaryotic spores. Liv e mature spores measure 4.4+/-2 x 2.3+/-0.3 mu m. Their wall is compos ed of an electron-dense exospore (45 nm thick), consisting of an inner electron-dense layer and an outer layer that is less dense, and of a clear endospore about 85 nm thick. The polar filament is isofilar with 12 to 13 coils in one rank. The polaroplast possesses an anterior lam ellar part and a posterior vesicular part.