The genus Choreonema in southern Australia and its subfamilial classification within the Corallinaceae (Rhodophyta)

Studies of southern Australian populations and of type material of Choreonema thuretii (Bornet) Schmitz have led to an emended characterization of the monotypic genus and to the recognition of the Choreonematoideae as a distinct subfamily of the Corallinaceae (Rhodophyta). A lectotype has been chosen for C. thuretii from Bornet specimens at PC; consequently, this specimen also becomes the generitype for Choreonema. Choreonema thuretii is widespread in southern Australia, occurring on species of Jania and Haliptilon in all seasons. Detailed studies of southern Australian collections and of type material have shown that the thallus of Choreonema lacks epithallial cells, lacks both cell fusions and secondary pit-connections, produces a unistratose conceptacle roof, bears spermatangia on both the floor and roof of the male conceptacle chamber, and has tetrasporangia which produce distinct apical plugs and are borne in groups within uniporate conceptacles. This unique combination of features does not allow Choreonema to be accommodated in any existing subfamily of the Corallinaceae and therefore a new subfamily is formally established. Historical notes on Choreonema, on its placement in the Corallinaceae, and on subfamilial classification within the Corallinaceae are included along with relevant nomenclatural data.