Studies on the association between Noteia anomala and Hormosira banksii (Phaeophyta)

Abstract

Anatomical, ultrastructural, ecological and physiological aspects of the relationship between the common brown alga, Hormosira banksii, and the obligate epiphyte Notheia anomala are described. The highest frequencies of infection by N. anomala occur in sexually mature H. banksii in tide-pool populations. Male and female H. banksii are equally affected, and the most common sites of infection are the receptacles where N. anomala attaches around the ostiole rather than within the conceptacle. Prolonged culture of N. anomala was only possible with media containing a filtered extract of the receptacles of the host species. Light and electron microscopy of the regions of thallus connecting N. anomala and H. banksii showed a wedge-shaped incursion of N. anomala in the H. banksii thallus, and very close contact between the adjacent cell walls of host and epiphyte, but there were no protoplasmic connections. The biological significance of the relationship between N. anomala and H. banksii is discussed.