ABSTRACT "Holospora acuminata" infects micronuclei of Paramecium bursaria, whereas "H.curviuscula" infects the macronucleus in other clones of the same host species. Because these microorganisms have not been cultivated, their description was done only by some morphological properties and the host and nuclear specificity. One 16S rRNA gene sequence of "H. curviuscula" is present in databanks. The systematic position of type strain of "H. curviuscula", namely MC-3T, was here determined. Moreover, for the first time, two strains of "H. acuminata", KBN10-1 and AC61-10T, were investigated. Phylogenetic analysis indicated that all three strains belonged to the genus Holospora, family Holosporaceae, order Rickettsiales within Alphaproteobacteria. [less] 0 BOOKMARKS · 65 VIEWS