Previously unknown apicomplexan species infecting Iceland scallop, Chlamys islandica (Müller, 1776), queen scallop, Aequipecten opercularis L., and king scallop, Pecten maximus L

• Published in: Journal of invertebrate pathology 2011-11, Vol.108 (3), p.147-155
• Main Authors: Kristmundsson, Árni, Helgason, Sigurður, Bambir, Slavko Helgi, Eydal, Matthías, Freeman, Mark A.
• Format: Article
• Language: English
• Subjects: Aequipecten opercularis; Animals; Apicomplexa; Biological and medical sciences; Bivalves; Chlamys; Chlamys islandica; DNA, Protozoan - analysis; DNA, Ribosomal - analysis; Eimeria - genetics; Eimeria - growth & development; extracellular space; Fundamental and applied biological sciences. Psychology; gametocytes; hemocytes; Host-Parasite Interactions; Iceland; Iceland scallop; Invertebrates; Life Cycle Stages - physiology; Marine; meronts; merozoites; Mollusca; Muscle, Skeletal - parasitology; muscles; oocysts; Parasites; Pecten maximus; Pectinidae - parasitology; Phylogeny; Protozoa; Protozoan Infections, Animal; scallops; Seawater; Shellfish - parasitology; sporogony; sporozoites; ultrastructure; zygote
• ISSN: 0022-2011; 1096-0805
• DOI: 10.1016/j.jip.2011.08.003

[Display omitted] ► Previously unknown apicomplexan species infecting three different scallops species. ► Unlike other species known to infect bivalves. ► Common in muscular tissues and inside haemocytes. ► Sexual and asexual forms in an apicomplexan life cycle detected. ► At present, its systematic position within the phylum Apicomplexa cannot be ascertained. Examination of three scallop species from three separate locations: Iceland scallop from Icelandic waters, king scallop from Scottish waters and queen scallop from Faroese and Scottish waters, revealed infections of a previously unknown apicomplexan parasite in all three scallop species. Developmental forms observed in the shells appeared to include both sexual and asexual stages of the parasite, i.e. merogony, gametogony and sporogony, which suggests a monoxenous life cycle. Meronts, gamonts, zygotes and mature oocysts were solely found in the muscular tissue. Zoites, which could be sporozoites and/or merozoites, were observed in great numbers, most frequently in muscles, both intracellular and free in the extracellular space. Zoites were also common inside haemocytes. Examination of the ultrastructure showed that the zoites contained all the major structures characterizing apicomplexans. This apicomplexan parasite is morphologically different from other apicomplexan species previously described from bivalves. Presently, its systematic position within the phylum Apicomplexa cannot be ascertained.