Morphology and life histories of Onslowia bahamensis sp. nov. and Verosphacela ebrachia gen. et sp. nov., with a reassessment of the Choristocarpaceae (Sphacelariales, Phaeophyceae)

Abstract Onslowia bahamensis sp. nov. and Verosphacela ebrachia gen. et sp. nov. are described. O. bahamensis produces propagules similar to those of O. endophytica Searles, and at 25°C in short days forms unilocular sporangia. Unispores develop into monoecious, anisogamous gametophytes which do not produce propagules. Female gametes germinate parthenogenetically to reproduce the gametophyte. Male gametes do not develop parthenogenetically. Fusion of male and female gametes results in formation of sporophytes. Verosphacela ebrachia occurs superficially endophytic in Spatoglossum schroederi, and forms unilocular or plurilocular zoidangia on separate filaments. No sexuality was observed in this species. Propagules are produced at 25°C under long-day conditions. Propagules lack apical cells and usually germinate from the basal cell. Onslowia endophytica, O. baharnensis and Verosphacela ebrachis possess characters allying them with Choristocarpus; they are placed in the Choristocarpaceae, which is seen to be ...