A NEW RECORD OF HERIBAUDIELLA FLUVIATILIS, A FRESHWATER BROWN ALGA (PHAEOPHYCEAE), FROM OREGON

Members of the algal class Phaeophyceae (brown algae) are almost entirely marine species. A few genera have been described from freshwater habitats, but their distribution and ecological requirements, especially in North America, are very poorly known. The 1st specimens of a freshwater species of brown algae from Oregon, Heribaudiella fluviatilis, were discovered in 3 localities of the McKenzie River, near McKenzie Bridge and Belknap Springs (44°22'N, 122°00'-15'W). This is the 4th extant population of this species known from the United States. The alga forms distinctive, macroscopic, dark brown patches on rocks in rapidly flowing water. In the McKenzie River it co-occurs, apparently year-round, with several other macrophytic algal species, including Prasiola mexicana, Zygnema sp. (sterile), Nostoc parmelioides, N. verrucossum, and Phormidium cf. autumnale. In cooler months the macroalgal species Ulothrix zonata and Hydrurus foetidus are also present with Heribaudiella· Photographs and ecological information are provided. We report a 380-km range extension south for the species, and thus far the most southerly population known from North America. This new record suggests that the alga may be more widespread than previously recognized and that other localities may be discovered with further study.