Rhododraparnaldia oregonica, a new freshwater red algal genus and species intermediate between the Acrochaetiales and the Batrachospermales

Abstract

Abstract An undescribed red alga was found in two streams of the Coastal Range and Cascades from Oregon, USA. This alga is characterized by barrel-shaped axial cells with a distinctly larger diameter (17.3–30.1 μm) than that of lateral branch cells (4.3–8.5 μm). The chromosome number of branch cells is n = c. 7. Unique spermatangial stalks produce two types of spermatangia at their tips. The carpogonium is typically acrochaetialean, with a swollen, cylindrical base and thin trichogyne, but carpospores germinate into a batrachospermalean-like chantransia phase. The gametophyte develops directly from this phase. DAPI relative fluorescence values are approximately twice as high for gonimoblast cells, carposporangia and chantransia cells as for the gametophyte vegetative cells and gametangia. Pit plugs have two cap layers, the outer typically domed. Nuclei in early mitotic prophase have one layer of perinuclear ER, a single-layered polar ring and chromatin associated with the nucleolus. Since the alga has cha...