The taxonomy ofUlva(Chlorophyceae) in the Netherlands

Abstract

On the basis of 160 living samples from 26 different stations five Ulva species were distinguished, and described for the Netherlands coast, namely U. pseudocurvata nov. spec., U. curvata (Kutz.) De Toni, U. lactuca L., U. rigida C.Ag. and U. scandinavica Bliding. Unialgal cultures were isolated from these samples in order to test the validity of the taxonomic criteria and to test the growth response of germlings and young blades to varying salinities. The following criteria appeared to be taxonomically valid, though most of them are subject to wide variation: (1) macroscopic morphology (including colour and texture); (2) form and arrangement of the cells in surface view; (3) the structure of the basal region (form and size of rhizoidal cells; the presence or absence of small-celled marginal wings; the presence or absence of longitudinal rhizoidal ribs; and the presence or absence of a flat central cavity in the lower basal region and the stipe); (4) the number of pyrenoids in a vegetative cell; (5) the a...