Abstract
400 individuals collected from Lake Nakuru (Kenya) were studied. The authors had previously reported on morphological variation of this species from Lake Shikotsu (Hokkaido Island) (Fujushima·Ko-Bayashi·Kurihara and Fujita 1992) .But for the current sample, particular features were the large number of individuals with linear-lanceolate frustules (P1.6 Figs E-d.95.8%), gread variation in the outer shape of valves, and individuals for which the fmstule of the central areas extended and connected to both margins (P1.8 Figs Z-f, 18.9%) .
Photomicrographs of individuals from the current samples were compared to those of type specimens of Fragilaria capucina (Krammer·Lange-Bertalot 1991, P1.108 Figs 1-8) and Exilaria vaucherae (Lange-Bertalot 1980, P1.1 Figs 26-34, Krammer·Lange-Bertalot 1991, P1.108 Figs 10-15) . With this, it may be thought, with Williams·Round (1987), that this species belongs toFragilaria vaucheriae. Among the present sample, some specimens have a strong resemblance toSynedra parvula (P1.4 Figs A-R) orSynedra amphicephala (P1.4 Figs S-W) .In addition, many specimens are intermediate betweenFragilaria vaucheriae and both of them, in their morphologies. The species ofSynedra parvulaandSynedra amphicephalashould be considered a synonyme ofFragilaria vaucheriae.
Fragilaria vaucheriae (Kuetzing) Boye-Pectersen, in Bot. Not, 1938, 167 Fig 1. 1938.
