A peculiar case of intraspecific variability in the Chinese Notholca dongtingensis (Rotifera: Monogononta: Brachionidae)

摘要

We review the rare Chinese rotifer Notholca dongtingensis Zhuge, Kutikova & Sudzuki, 1998, including abundant material collected during the winter months of 2009-2011 in and around the man-made Dishui Lake Southeast of Shanghai, PR China. Both an SEMstudy of its trophi and an account of its intraspecific variability are provided. The latter consists in particular of a unique and previously unknown type of spine formation involving the anterolateral spines, a character previously considered morphologically constant and even diagnostic in Notholca and related genera. The observations indicate that phenotypic plasticity invoked by a plesiomorphic triggering mechanism is not per se connected to the type or position of structures developed, but may activate responses resulting in the formation of quite different, autapomorphic structures throughout monogonont Rotifera.