Ciliates inhabiting Isopoda: Epibiont-Basibiont relations

Abstract

The present work dealing with analysis of relations the ciliate (Ciliophora) epibiont species with marine, freshwater, and terrestrial basibiont isopods. Altogether 200 ciliate species, including one form and two varieties of ciliates were found on 99 species of aquatic and terrestrial isopods. The found ciliate species belong to five classes: Heterotrichea, Litostomatea, Phyllopharyngea, Suctorea, and Oligohymenophorea. Based on the analysis of known ciliate epibioses on Isopoda, the evolutionary trends in the development of epibiont/endobiont-basibiont associations are discussed. The general trend was the transition from facultative to obligate epibiosis, occurred against the background of the more general trend, i.e. the transition of ciliates to the sessile mode of life. The second level trend is characterized by ciliate adaptations to epibiosis on molting hosts by the synchronization of the ciliate life cycle with the molting of basibionts. The trend of the third level was connected with the development of specificity to the basibiont taxon and selectivity in localization, based on the synchronization of the life cycle of epibionts with the mating of basibionts.