Fissurina as an ectoparasite

Abstract. For such a large and ecologically diverse group of organisms, foraminifera have produced remarkably few examples of parasites. They have, however, been recorded as ectoparasites on other foraminifera (Le Calvez, 1947; Haynes, 1981) and on bivalve molluscs (Todd, 1965; Alexander and Delaca, 1987). With respect to foraminiferal hosts, Le Calvez (1947) described Entosolenia ( = Fissurina) marginata as an ectoparasite that fed on granules from the pseudopodial reticulum of Discorbis villardeboanus. He observed specimens of F. marginata positioning themselves over the aperture of Discorbis, either moving there on their own or being carried along by the host’s pseudopodia, and remaining until leaving to undertake vegetative reproduction. After secretion of their tests, the new gamonts returned onto Discorbis. From his studies of mixed cultures, Le Calvez considered Fissurina marginata to be restricted to this single host and to die in its absence. It is thus apparently an obligate parasite with high host specificity.

Haynes (1981), apparently from unpublished data, considered both Fissurina and Lagena to be ectoparasitic on other foraminifera, with their tests and apertural regions evolved for parasitic feeding. However, to the best of our knowledge, the observations outlined above have not been repeated and there are few recent reports of an ectoparasitic lifestyle for Fissurina (see Haward & Haynes, 1976).

Specimens of Fissurina spp. are not uncommon in Fijian sediments. During the study of a sample of recent sediment collected from Bligh Water off Viti Levu, Fiji, a specimen of Fissurina, here referred to F. submarginata (Boomgart), was found . . .