Phylogenetics of Bonamia parasites based on small subunit and internal transcribed spacer region ribosomal DNA sequence data.

The genus Bonamia (Haplosporidia) includes economically significant oyster parasites. Described species were thought to have fairly circumscribed host and geographic ranges: B. ostreae infecting Ostrea edulis in Europe and North America, B. exitiosa infecting O. chilensis in New Zealand, and B. roughleyi infecting Saccostrea glomerata in Australia. The discovery of B. exitiosa-like parasites in new locations and the observation of a novel species, B. perspora, in non-commercial O. stentina altered this perception and prompted our wider evaluation of the global diversity of Bonamia parasites. Samples of 13 oyster species from 21 locations were screened for Bonamia spp. by PCR, and small subunit and internal transcribed spacer regions of Bonamia sp. ribosomal DNA were sequenced from PCR-positive individuals. Infections were confirmed histologically. Phylogenetic analyses using parsimony and Bayesian methods revealed one species, B. exitiosa, to be widely distributed, infecting 7 oyster species from Australia, New Zealand, Argentina, eastern and western USA, and Tunisia. More limited host and geographic distributions of B. ostreae and B. perspora were confirmed, but nothing genetically identifiable as B. roughleyi was found in Australia or elsewhere. Newly discovered diversity included a Bonamia sp. in Dendostrea sandvicensis from Hawaii, USA, that is basal to the other Bonamia species and a Bonamia sp. in O. edulis from Tomales Bay, California, USA, that is closely related to both B. exitiosa and the previously observed Bonamia sp. from O. chilensis in Chile.

Paramarteilia canceri sp. n. (Cercozoa) in the European edible crab (Cancer pagurus) with a proposal for the revision of the order Paramyxida Chatton, 1911.

A new species, Paramarteilia canceri sp. n., is described using light and electron microscopy from the edible crab Cancer pagurus L. captured from the English Channel. No external symptoms were noted, although infected animals were typically lethargic and unresponsive to external stimuli. Organs of infected animals were shrunken and collapsed compared with apparently healthy individuals. Although the infection was systemic, marked host responses were only noted in the hepatopancreas where the parasite induced a pronounced haemocytic infiltration. Prevalence of infection throughout the study was 1.1%, with a maximum monthly prevalence of 3%. The intracellular parasite was typically 15 microm in length and composed of a primary cell containing up to three secondary cells derived by internal cleavage. Each secondary cell contains two bicellular spores. The parasite is readily differentiated from the other described paramyxean species by a combination of the number of secondary and tertiary cells. In light of this new discovery, a revision of the order Paramyxida Chatton, 1911 is proposed based upon comparison to the original descriptions of this parasite group in various species of invertebrate hosts. The proposed classification is based on the number of cells within the spores (tertiary cells), so that only three genera remain within the order, namely Marteilia Grizel, Comps, Bonami, Cousserans, Duthoit et Le Pennec, 1974, Paramarteilia Ginsburger-Vogel et Desportes, 1979 and Paramyxa Chatton, 1911. Subsequent discrimination of species is based on a combination of the number of secondary cells within the primary cell and the number of tertiary cells within secondary cells. It is proposed that the genus Marteilioides Comps, Park et Desportes, 1986 is suppressed and the type species of the genus, M. chungmuensis Comps, Park et Desportes, 1986, is transferred to Marteilia and that the other representative of the genus, M. branchialis Anderson et Lester, 1992, is transferred to Paramarteilia. Further, Paramyxoides Larsson et Køie, 2005 is considered as a junior synonym of Paramyxa and its type and only species, Paramyxoides nephtys Larsson et Køie, 2005, is transferred to Paramyxa.

Bonamia perspora n. sp. (Haplosporidia), a parasite of the oyster Ostreola equestris, is the first Bonamia species known to produce spores.

Examination of the oyster Ostreola equestris as a potential reservoir host for a species of Bonamia discovered in Crassostrea ariakensis in North Carolina (NC), USA, revealed a second novel Bonamia sp. Histopathology, electron microscopy, and molecular phylogenetic analysis support the designation of a new parasite species, Bonamia perspora n. sp., which is the first Bonamia species shown to produce a typical haplosporidian spore with an orifice and hinged operculum. Spores were confirmed to be from B. perspora by fluorescent in situ hybridization. Bonamia perspora was found at Morehead City and Wilmington, NC, with an overall prevalence of 1.4% (31/2,144). Uninucleate, plasmodial, and sporogonic stages occurred almost exclusively in connective tissues; uninucleate stages (2-6 microm) were rarely observed in hemocytes. Spores were 4.3-6.4 microm in length. Ultrastructurally, uninucleate, diplokaryotic, and plasmodial stages resembled those of other spore-forming haplosporidians, but few haplosporosomes were present, and plasmodia were small. Spore ornamentation consisted of spore wall-derived, thin, flat ribbons that emerged haphazardly around the spore, and which terminated in what appeared to be four-pronged caps. Number of ribbons per spore ranged from 15 to 30, and their length ranged from 1.0 to 3.4 microm. Parsimony analysis identified B. perspora as a sister species to Bonamia ostreae.