title: Parahepatospora carcini n. gen., n. sp., a parasite of invasive Carcinus maenas with intermediate features of sporogony between the Enterocytozoon clade and other microsporidia.
abstract: Parahepatospora carcini n. gen. n. sp., is a novel microsporidian parasite discovered infecting the cytoplasm of epithelial cells of the hepatopancreas of a single Carcinus maenas specimen. The crab was sampled from within its invasive range in Atlantic Canada (Nova Scotia). Histopathology and transmission electron microscopy were used to show the development of the parasite within a simple interfacial membrane, culminating in the formation of unikaryotic spores with 5-6 turns of an isofilar polar filament. Formation of a multinucleate meront (>12 nuclei observed) preceded thickening and invagination of the plasmodial membrane, and in many cases, formation of spore extrusion precursors (polar filaments, anchoring disk) prior to complete separation of pre-sporoblasts from the sporogonial plasmodium. This developmental feature is intermediate between the Enterocytozoonidae (formation of spore extrusion precursors within the sporont plasmodium) and all other Microsporidia (formation of spore extrusion precursors after separation of sporont from the sporont plasmodium). SSU rRNA-based gene phylogenies place P. carcini within microsporidian Clade IV, between the Enterocytozoonidae and the so-called Enterocytospora-clade, which includes Enterocytospora artemiae and Globulispora mitoportans. Both of these groups contain gut-infecting microsporidians of aquatic invertebrates, fish and humans. According to morphological and phylogenetic characters, we propose that P. carcini occupies a basal position to the Enterocytozoonidae. We discuss the discovery of this parasite from a taxonomic perspective and consider its origins and presence within a high profile invasive host on the Atlantic Canadian coastline.
authors.affiliation: Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Pathology and Molecular Systematics Team, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK. Electronic address: bs09jb@leeds.ac.uk.
authors.forename: Jamie
authors.initials: J
authors.lastname: Bojko
authors.affiliation: Department of Biomedical Sciences, University of Prince Edward Island, Charlottetown, Prince Edward Island C1A 4P3, Canada. Electronic address: fclark@mta.ca.
authors.forename: Fraser
authors.initials: F
authors.lastname: Clark
authors.affiliation: Pathology and Molecular Systematics Team, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK; European Union Reference Laboratory for Crustacean Diseases, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK; Department of Life Sciences, Natural History Museum London, Cromwell Road, London SW7 5BD, UK. Electronic address: david.bass@cefas.co.uk.
authors.forename: David
authors.initials: D
authors.lastname: Bass
authors.affiliation: Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK. Electronic address: A.Dunn@Leeds.ac.uk.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Dunn
authors.affiliation: Department of Animal Science and Aquaculture, Dalhousie University Faculty of Agriculture, 58 River Road, Truro, Nova Scotia B2N 5E3, Canada. Electronic address: Sarah.Stewart-Clark@Dal.Ca.
authors.forename: Sarah
authors.initials: S
authors.lastname: Stewart-Clark
authors.affiliation: Epidemiology and Risk Team, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK. Electronic address: paul.stebbing@cefas.co.uk.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Stebbing
authors.affiliation: Pathology and Molecular Systematics Team, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK; European Union Reference Laboratory for Crustacean Diseases, Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, Weymouth, Dorset DT4 8UB, UK. Electronic address: grant.stentiford@cefas.co.uk.
authors.forename: Grant D
authors.initials: GD
authors.lastname: Stentiford
mesh_terms: D000818:Animals; D003386:Brachyura / Q000469:parasitology*; D046529:Microscopy, Electron, Transmission; D021861:Microsporidia, Unclassified / Q000145:classification* / Q000235:genetics* / Q000648:ultrastructure; D010802:Phylogeny; D016133:Polymerase Chain Reaction
keywords: Abelspora; Enterocytospora; Enterocytozoonidae; Invasive-pathogens; Phylogenetics; Taxonomy