Marteilia cochillia sp. nov., a new Marteilia species affecting the edible cockle Cerastoderma edule in European waters

Cockle Cerastoderma edule fishery collapse in the Ría de Arousa (Galicia, NW Spain) associated with the protistan parasite Marteilia cochillia

“…The comparison of the consensus sequence of the Galician cockle parasite including the IGS, ITS1 and 18S regions with the fragment sequences of those regions of the M. cochillia infecting cockles from Catalonia showed 99 to 100% homology. Phylogenetic analyses of ITS1 and IGS sequences allocated M. refringens into a different clade from that including the cockle parasites from Galicia and Catalonia, which is consistent with the analysis of IGS sequences performed by Carrasco et al (2013), in which the sequences of M. refringens and those of M. cochillia were allocated into different clades. The molecular similarity supports considering the parasite of Galician cockles as M. cochillia, while the morphological differences mentioned above should be further analysed to assess whether they correspond to intraspecific variability or inaccurate examination.…”

“…The aetiological agent of marteiliosis in Galician cockles proliferated through host digestive diverticula, where sporulation took place. Similarly, sporulation takes place in host digestive diverticula in the case of M. refringens (Grizel et al 1974, Villalba et al 1993a, M. sydneyi (Perkins & Wolf 1976, Kleeman & Adlard 2000, Kleeman et al 2002, M. christenseni (Comps 1983), M. cochillia (Carrasco et al 2011(Carrasco et al , 2013 and Marteilia sp. in fecting cockles in France (Comps et al 1975).…”

“…parasitising cockles in France (Comps et al 1975) and in the parasite infecting Galician cockles, al though hyperparasitisation with microsporidians has also been observed in M. refringens infecting Ostrea edulis (Comps et al 1979) and M. galloprovincialis (Villalba et al 1993a (López & Darriba 2006), larger than those of the Galician cockle parasite. The comparison of the Marteilia parasite of the Galician cockles with the description of morphological characters of M. cochillia infecting cockles from Catalonia (Carrasco et al 2013) reveals similarities and disagreements; the number of sporangia per primary cell is lower in the parasite from Catalonian cockles, but Carrasco et al (2013) stated that number (4) based on TEM observations, which is much less accurate than estimation based on examining serial histological sections of infected cockles, due to the size of primary cells and sporangia. In fact, the images of histological sections included in the paper on the Marteilia sp.…”

“…type C (Carrasco et al 2012). Recent transmission electron microscopy (TEM) characterisation allowed completion of the new species description of M. cochillia (Carrasco et al 2013). …”

Parasites, pathological conditions and resistance to Marteilia cochillia in lagoon cockle Cerastoderma glaucum from Galicia (NW Spain)

“…Carrasco et al (2011) collected cockles from the Delta de l'Ebre (Spanish Mediterranean coast) and considered them to be C. edule, although this species rarely occurs in the Mediterranean Sea , Longshaw & Malham 2013 while C. glaucum is widely distributed (Nikula & Väinölä 2003). Carrasco et al (2011) also detected infection with a Marteilialike parasite in 40% of those cockles, some of them with heavy infection intensity, with fully mature para sites, which were later identified as the new species M. cochillia (Carrasco et al 2013). If cockles from the Delta de l'Ebre were C. glaucum, then the type host of the parasite would be C. glaucum, which would contrast with the resistance of C. glaucum to M. cochillia supported by results from our survey.…”