Reproduction and life cycle of Sorites orbiculus (Forskål), Foraminifer

Abstract

A sample of megalospheric Sorites orbiculus from lagoon Awa di Oostpunt, Curaçao, contains a surprisingly large percentage of adults with brood in the reproduction chambers. Measurements of the initial chambers of a parent do not differ significantly from those of the offspring. This suggests a paratrimorphic life cycle. Two specimens contain undeveloped embryos consisting of protoconch only or of protoconch with incipient flexostyle. It is concluded that protoconch and flexostyle are separate chambers, and that brood formation proceeds with considerable but not perfect synchronism. These protoconchs have thin walls and are perfectly circular in outline; they will be somewhat deformed by the formation of the flexostyle around them after which the wall will be thickened. The question is raised whether Leutenegger's two plurinucleate specimens with micronuclei could not be diploid megalospheric schizont/gamonts in which case the haploid generation would be reduced to the micronuclei and gametes. The diploidy of such a parent can be tested if the gametes produced by it can fuse inter se into viable zygotes.