A new subspecies of Myriophyllum oguraense (Haloragaceae) from China

摘要

Myriophyllum oguraense Miki subsp. yangtzense D. Wang subsp. nova (Haloragaceae) from China, is described and illustrated. An identification key to the morphologically most similar taxa is provided. The new subspecies differs from M. oguraense subsp.oguraense by having large fruits and mericarps with two longitudinal ridges on the dorsal surface. The two taxa exhibit a disjunct distribution pattern, M. oguraense subsp. yangtzense being confined to the lower Yangtze valley in China, whereas M. oguraense subsp. oguraense is restricted to Japan.