Coccomyxa parasitica sp. Noy. (cocco- myxaceae, chlorococcales), a parasite of giant scallops in newfoundland

Abstract

Coccomyxa parasitica sp. nov. (Coccomyxaceae; Chlorococcales) is described as a parasite of the marine giant scallop, Placopecten magellanicus Gmelin, from Newfoundland, Canada. Cells occur in colonies distributed through various host organs, but especially in the mantle fold. Cell morphology is highly variable, although characterised by the possession of a distinct hyaline tip which is reduced or absent in culture. Pyrenoids are lacking, 1-3 parietal chloroplasts occur and the cell wall lacks cellulose. Reproduction is by 2, 4 or 8 autospores in the host, and by 2, 4, 8 or 16 autospores in culture. Sexual reproduction is lacking. Pigment analysis reveals the predominance of chlorophyll a, with chlorophyll b, α- and β-carotene and neoxanthin also present. The parasitism is regarded as at best facultative, although free-living C. parasitica is at present not known. © 1974 Taylor & Francis Group, LLC.