Taxonomic implications of gamete fusions in the parasitic brown alga Herpodiscus durvillaeae

Abstract

Field material of Herpodiscus durvillaeae, a New Zealand endemic parasitic brown alga growing in the thalli of Durvillaea antarctica, was studied in the laboratory. Pale zoids released from diminutive gametophytes, which were attached to the walls of unilocular sporangia and vegetative filaments of Herpodiscus, acted as isogametes. A heteromorphic life cycle with alternation of an endophytic parasitic sporophyte and a diminutive gametophyte is thus proposed for H. durvillaeae, and taxonomic implications of this life history are discussed. Key words: Herpodiscus durvillaeae, sexuality, life history, Phaeophyceae, Durvillaea antarctica, parasite.