Gracilarioid species (Gracilariaceae, Rhodophyta) in southern Africa, with a description of Gracilariopsis funicularis sp. nov.

Abstract

Southern African gracilarioids have previously been assigned to Gracilaria gracilis and Gracilariopsis lemaneiformis. Recent molecular evidence indicates that at least three gracilarioid species, G. gracilis, Gracilariopsis longissima and an undescribed Gracilariopsis species occur in this region. The main economic species in Saldanha Bay on the south-west coast of South Africa and Lüderitz Bay (Namibia) is G. gracilis. It is possible that the population of Gs longissima in St Helena Bay (South Africa) is a recent introduction. Gracilariopsis funicularis sp. nov. has a disjunct distribution along the coast of central Namibia, and in a discrete estuarine location in South Africa. These plants display two morphotypes superficially resembling Gracilariopsis tenuifrons (in South Africa) and Gs longissima (in Namibia). It is postulated that Namibian populations of the novel Gracilariopsis species may have economic significance, particularly for aquaculture, being the only gracilarioids in southern Africa that are fertile on a regular basis.