title: Hyperspora aquatica n.gn., n.sp. (Microsporidia), hyperparasitic in Marteilia cochillia (Paramyxida), is closely related to crustacean-infecting microspordian taxa.
abstract: The Paramyxida, closely related to haplosporidians, paradinids, and mikrocytids, is an obscure order of parasitic protists within the class Ascetosporea. All characterized ascetosporeans are parasites of invertebrate hosts, including molluscs, crustaceans and polychaetes. Representatives of the genus Marteilia are the best studied paramyxids, largely due to their impact on cultured oyster stocks, and their listing in international legislative frameworks. Although several examples of microsporidian hyperparasitism of paramyxids have been reported, phylogenetic data for these taxa are lacking. Recently, a microsporidian parasite was described infecting the paramyxid Marteilia cochillia, a serious pathogen of European cockles. In the current study, we investigated the phylogeny of the microsporidian hyperparasite infecting M. cochillia in cockles and, a further hyperparasite, Unikaryon legeri infecting the digenean Meiogymnophallus minutus, also in cockles. We show that rather than representing basally branching taxa in the increasingly replete Cryptomycota/Rozellomycota outgroup (containing taxa such as Mitosporidium and Paramicrosoridium), these hyperparasites instead group with other known microsporidian parasites infecting aquatic crustaceans. In doing so, we erect a new genus and species (Hyperspora aquatica n. gn., n.sp.) to contain the hyperparasite of M. cochillia and clarify the phylogenetic position of U. legeri. We propose that in both cases, hyperparasitism may provide a strategy for the vectoring of microsporidians between hosts of different trophic status (e.g. molluscs to crustaceans) within aquatic systems. In particular, we propose that the paramyxid hyperparasite H. aquatica may eventually be detected as a parasite of marine crustaceans. The potential route of transmission of the microsporidian between the paramyxid (in its host cockle) to crustaceans, and, the 'hitch-hiking' strategy employed by H. aquatica is discussed.
authors.affiliation: European Union Reference Laboratory for Crustacean Diseases,Centre for Environment, Fisheries and Aquaculture Science (Cefas),Barrack Road,Weymouth,Dorset DT4 8UB,UK.
authors.forename: G D
authors.initials: GD
authors.lastname: Stentiford
authors.affiliation: Centro de Investigacións Mariñas (CIMA),Consellería do Mar, Xunta de Galicia, Aptdo.13, 36620 Vilanova de Arousa,Spain.
authors.forename: A
authors.initials: A
authors.lastname: Ramilo
authors.affiliation: Centro Tecnológico del Mar, Fundación CETMAR,Eduardo Cabello s/n, 36208 Vigo,Spain.
authors.forename: E
authors.initials: E
authors.lastname: Abollo
authors.affiliation: Pathology and Molecular Systematics Team, Weymouth Laboratory,Centre for Environment, Fisheries and Aquaculture Science (Cefas),Dorset DT4 8UB,UK.
authors.forename: R
authors.initials: R
authors.lastname: Kerr
authors.affiliation: European Union Reference Laboratory for Crustacean Diseases,Centre for Environment, Fisheries and Aquaculture Science (Cefas),Barrack Road,Weymouth,Dorset DT4 8UB,UK.
authors.forename: K S
authors.initials: KS
authors.lastname: Bateman
authors.affiliation: Pathology and Molecular Systematics Team, Weymouth Laboratory,Centre for Environment, Fisheries and Aquaculture Science (Cefas),Dorset DT4 8UB,UK.
authors.forename: S W
authors.initials: SW
authors.lastname: Feist
authors.affiliation: Pathology and Molecular Systematics Team, Weymouth Laboratory,Centre for Environment, Fisheries and Aquaculture Science (Cefas),Dorset DT4 8UB,UK.
authors.forename: D
authors.initials: D
authors.lastname: Bass
authors.affiliation: Centro de Investigacións Mariñas (CIMA),Consellería do Mar, Xunta de Galicia, Aptdo.13, 36620 Vilanova de Arousa,Spain.
authors.forename: A
authors.initials: A
authors.lastname: Villalba
mesh_terms: D000818:Animals; D056907:Cercozoa / Q000469:parasitology* / Q000648:ultrastructure; D003445:Crustacea / Q000469:parasitology; D006790:Host-Parasite Interactions; D016814:Microsporidia / Q000235:genetics* / Q000502:physiology* / Q000648:ultrastructure; D010802:Phylogeny; D016053:RNA, Protozoan / Q000235:genetics
chemical_list: D016053:RNA, Protozoan
keywords: 
                 Marteilia
              ; Cercozoa; Cryptomycota; Digenea; Fungi; Paramyxea; Phylogeny