Zehn Subgenera für achtzehn Pisidium-arten?

A reply is given to a proposal made by Kuiper (1993, CB 275: 150- 155) towards a subgeneric grouping of Pisidium species found in the Netherlands. The following modifications are suggested: The species P. milium, pseudosphaerium, subtruncatum and pulchellum should be grouped in a common subgenus: Tetragonocyclas. Some tentative groupings may reduce the number of subgenera from ten to seven: P. hibernicum in Henslowiana, P. nitidum in Cyclocalyx, P. moitessierianum in Odhneripisidium. The arrangement published in Kuiper’s table is altered according to a more probable sequence of evolutionary transformations which is based on rising numbers of derived character states.