Batrachospermum latericium sp. nov. (Batrachospermales, Rhodophyta) from Tasmania, Australia, with new observations on B. atrum and a discussion of their relationships

Batrachospermum latericium sp. nov. occurs in humic streams in the Southwest National Park in Tasmania and is thus far collected from New Harbour to the Old River catchment. Like B. diatyches Entwisle. also a Tasmanian endemic, the thallus of the new species has brick-like rhizoidal filament cells and a large apical cell. The primary fascicles, however, are more like those of B. puiggarianum Grunow from South America and Africa. New character states, including the sporadic occurrence of spermatangia on invoiucral bracts and 'shortly indeterminate' gonimoblast filaments, are reported for the widespread B. atrum (Hudson) Harvey. There is no support for the recognition in Australia or New Zealand of the recently described B. androinvolucruin Sheath et cd.. characterized by the production of spermatangia exclusively on invoiucral filaments. In an exemplar cladistic analysis based on morphological characters, taxa included currently in the section Setacea formed a monophyletic clade and within this, the two Australian endemics were sister taxa. Brick-like rhizoidal filament cells, a large thallus apical cell and shortly indeterminate gonimoblast filaments are derived character states within Batrachospermales.