RHODODRAPARNALDIA-OREGONICA, A NEW FRESH-WATER RED ALGAL GENUS AND SPECIES INTERMEDIATE BETWEEN THE ACROCHAETIALES AND THE BATRACHOSPERMALES

An undescribed red alp was found in two streams of the Coastal Range a nd Cascades from Oregon, USA. This alga is characterized by barrel-sha ped axial cells with a distinctly larger diameter (17.3-30.1 mum) than that of lateral branch cells (4.3-8.5 mum). The chromosome number of branch cells is n = c. 7. Unique spermatangial stalks produce two type s of spermatangia at their tips. The carpogonium is typically acrochae tialean, with a swollen, cylindrical base and thin trichogyne, but car pospores germinate into a batrachospermalean-like chantransia phase. T he gametophyte develops directly from this phase. DAPI relative fluore scence values are approximately twice as high for gonimoblast cells, c arposporangia and chantransia cells as for the gametophyte vegetative cells and gametangia. Pit plugs have two cap layers, the outer typical ly domed. Nuclei in early mitotic prophase have one layer of perinucle ar ER, a single-layered polar ring and chromatin associated with the n ucleolus. Since the alga has characteristics of both the Acrochaetiale s and the Batrachospermales its classification is uncertain. It is nam ed Rhododraparnaldia oregonica gen. et sp. nov., the generic name deno ting the abrupt change in cell diameter between axial and branch cells , like the chlorophyte genus Draparnaldia.