STUDIES IN THE TABULARIA FASCICULATA COMPLEX

Abstract

Original material of Diatoma fasciculatum C. A. Agardh 1812, Diatoma tabulatum C. A. Agardh 1832, and Synedra affinis Kützing 1844, has been studied. Lectotypes are selected for Diatoma fasciculatum and Diatoma tabulatum. The type material of Diatoma fasciculatum agrees with Tabularia fasciculata (C. A. Agardh) Williams & Round 1986. The new combinations Tabularia tabulata (C. A. Agardh) Snoeijs and Tabularia affinis (Kützing) Snoeijs are proposed. All three species are here treated as Tabularia Williams & Round, although it may be necessary to split the genus in the future. Further taxonomic and ecological observations on fasciculata-like diatoms were made from recently gathered material, including numerous samples along the salinity gradient of the Baltic Sea (from 11 down to <1°/oo), and year-round samples of living diatoms from a site with a salinity of 5°/oo. Frustule structure, chloroplasts, colony-type, ecological distribution, and cell morphometric data are discussed. Tabularia affinis was not found in the Baltic Sea; it is probably a marine species (type locality Adriatic Sea). In the Baltic Sea, four fasciculata-like forms with different salinity preferences and consistent morphologies can be recognised; Tabularia fasciculata, Tabularia tabulata, a third form which is best left as Tabularia of. laevis Kützing, and finally a fourth fasciculata-like form which was initially recognised on the basis of its chloroplast morphology.