Expansion of the Beta-Proteobacterial Genus Ca. Ichthyocystis: A Case Report of Epitheliocystis in the Pompano Trachinotus ovatus

Epitheliocystis is a disease caused by a wide variety of host-specific intracellular bacteria infecting fish gills. In the Mediterranean Sea, epitheliocystis has been recently associated with a novel genus of beta-proteobacteria, the Ca. Ichthyocystis genus. In the present study, we report a case of epitheliocystis in a wild-caught specimen of pompano Trachinotus ovatus in Crete, Greece. Molecular analysis of partial 16s rRNA sequence led to the discovery of a putative novel species of the Ca. Ichthyocystis genus. Investigation of the phylogenetic relationship between closely related sequences deposited in NCBI suggests that bacterial ancestors in gilthead seabream might have a pivotal role in the differentiation of genus.