| Abstract: | The fern Athyrium crenulato-serrulatum Makino is found in the whole of Northeastern Asia embracing Northeastern China, Korea, Japan, Ussuri and the Far East USSR. It is similar to the European Athyrium distentifolium, formerly knownas A. alpestre, in having exindusiate round or ovate sori, but differs in several essential characters, such as the well-spaced fronds are biseriately arranged along a thick and long-creeping rhizome, the base of stipe is thickened and not attenuated towards the point of attachment, the deltoid-ovate lamina with the basal pinnae as longas those next above, which all are distinctly petiolate and the rachis, costis and especially the costules of pinnules clad in fine pale-colored generally septate hairs underneath. All these clearly show that the fern in question is not an Athyrium sen. str.neither Pseudoathyrium Newman to which latter the fern was referred by Nakai.However, we have been long suspicious of its proper systematic position. In his recentmonograph on the genus Cornopteris (Acta Phytotax. Geobot. 30: 104. 1979.) Katohas pointed out that C.crenulato-serrulata (Makino) Nakai “has the northernmostdestribution in the genus and exhibits a few characteristics similar to Athyrium, theswollen base of stipes with projections and cartilaginous lamina margin. By thesecharacteristics the species is clearly discriminated from other species”. According toKurita (1964), Mitui (1970) and Karo (1978) the species in question has chromosomenumbers n=40, the base number of the subfamily Athyrioides instead of x=41, thebase number of the subfamily Diplazioides including Cornopteris Nakai. Since thefern in question fits no other athyrid genera, hence a new genus is proposed. |
