AN ACCOUNT OF SOUTHERN AUSTRALIAN SPECIES OF LITHOTHAMNION (CORALLINACEAE, RHODOPHYTA)

Lithothamnion (Corallinaceae, Rhodophyta) is represented in southern A ustralia by at least two species: L. muelleri, the type species of the genus, and L. indicum. Detailed accounts are provided along with a ke y to the species, and information on distribution, seasonality and hab itat, nomenclature and synonymy, and infraspecific taxonomy. Two chara cters associated with tetrasporangial conceptacle roof anatomy are con sidered diagnostic of the two southern Australian species. Twenty-five characters used by other authors to separate species of Lithothamnion were examined; none were found to be diagnostic of L. muelleri or L. indicum, and only one (plant habit) was sometimes found to be useful a s an ancillary character. None of the measured characters assessed cou ld be used in a diagnostic or ancillary manner. The status and disposi tion of 22 other specific and infraspecific taxa ascribed to Lithotham nion and reported from southern Australia are summarised; 3 are consid ered synonyms of L. indicum or L. muelleri, 12 are referable to other genera, 6 are considered to be of uncertain status, and 1 constitutes an unconfirmed record.