Detection of a new bacterium of the family Holosporaceae (Alphaproteobacteria: Holosporales) associated with the oribatid mite Achipteria coleoptrata

We detected an unknown bacterium in Achipteria coleoptrata (Acari: Oribatida). Its 16S rDNA gene sequence showed 89% identity to the endosymbiont “Candidatus Nucleicultrix amoebiphila” from amoebae and “Candidatus Gortzia sp.” from ciliates. Phylogenetic analysis revealed that the microorganism is a member of the family Holosporaceae, order Holosporales of Alphaproteobacteria. Its occurrence in Oribatida is enigmatic. It cannot be excluded that it is a symbiont of Oribatida as well as it is an endosymbiont of a smaller, even unicellular, organisms living inside the mite. The issue of the occurrence of this microorganism is interesting and further research is needed to gain the knowledge of its role and the nature of bacterium-host interaction.