Reproductive morphology and life histories of Southern AfricanGymnogongrusspecies (Rhodophyta, Phyllophoraceae)

Abstract

Using culture techniques, the life histories of four southern African Gymnogongrus species are shown to conform to one of two fundamental types known in this genus. In G. dilatatus, carpotetrasporangia are borne in filaments which make up wart-like nemathecia on the gametophyte. In culture, the carpotetraspores produced crusts from which new gametophytes grew. These in turn produced fertile nemathecia. G. complicatus, G. glomeratus and G. polycladus have separate crustose tetrasporophytes in their life histories. Female gametophytes of these species have immersed cystocarps with specialized openings or carpostomes. Carpospores produced crusts which did not become fertile in laboratory culture. Within 2–3 weeks of transfer to the sea they bore intercalary, cruciately divided tetrasporangia among cells of the ascending filaments. The probable life histories of southern African G. vermicularis, G. intermedius and one undescribed species are discussed in relation to their reproductive morphology.