**Gomphonema varioreduncum** sp. nov., a new species from northern and western Europe and a re-examination of **Gomphonema exilissimum **
Faculty of Sciences. Biology
Diatom research / International Society for Diatom Research. - Bristol
, p. 303-316
University of Antwerp
Gomphonema parvulum Kützing and morphologically similar species can be difficult to distinguish while differing markedly in their ecology. It is important to identify these species correctly if the ecological status of their habitats is to be assessed accurately. Here, two species in this group are documented using light and scanning electron microscopy. The type material of G. exilissimum (Grunow) Lange-Bertalot & E. Reichardt in the Van Heurck Collection, Meise, was examined, as well as recently collected populations from Scotland and Sweden. A new species, G. varioreduncum Jüttner, Ector, E. Reichardt, Van de Vijver & E.J. Cox which is similar to G. exilissimum and resembles G. cymbelliclinum E. Reichardt & Lange-Bertalot in outline is described and populations from northern and western Europe are illustrated.