Morphology and molecular phylogeny of four epibiotic ciliates (Ciliophora, Peritrichia) from farmed red swamp crayfish Procambarus clarkii Girard, 1852, with notes on the geographic distributions of related taxa

Aquaculture of red swamp crayfish Procambarus clarkii is an emerging farming industry in China. As shown recently, one of the most significant diseases affecting the red swamp crayfish is caused by overabundance of epibiotic peritrichs, a group of ciliated protists that are commonly found living as epibionts on aquatic animals. Nevertheless, few studies focusing on this issue have been performed. As part of a faunal study carried out in the Lake Weishan Wetland, China, four colonial sessilid peritrichs, namely Epicarchesium granulatum, Epistylis bimarginata, Epistylis semiciculus, and Zoothamnium procerius, attached to P. clarkii are documented. For each species, redescriptions and improved diagnoses are supplied. As a further aid to identification, 14 new rDNA sequences of these four and a closely related species were obtained. In addition, as an aid for future studies on epibiotic ciliates, we supply a list and information about recent integrative studies that document the geographic distributions of related taxa.