Gregarines of west coast barnacles: Cephaline Gregarines of barnacles from the north east Pacific Ocean
Gregarines are parasitic protozoa belonging to the sporozoan subclass Telosporidia. They occur most often in invertebrate groups with a metameric level of development. Some, however, have been described from mollusks which do not have a metameric level of development (Cheng, 1967; Leger and Duboscq, 1908). The eugregarines of arthropods, including barnacles, are typically members of the suborder Cephalina. Cephaline gregarines are described as polycystid organisms to contrast them with the unsegmented monocystid gregarines. The bodies of cephaline gregarines are divided into two segments, an anterior protomerite separated from the posterior deutomerite by a membrane which does not restrict movement of the endo-plasm but does set off the nucleus in the deutomerite. A holdfast, the epimerite, is located on the anterior end of the young sporont. The gregarine remains temporarily attached externally to the cell in which it developed. It subsequently loses the epimerite and becomes a trophozoite which moves about freely, usually in the gut lumen.