PT Journal AU Reichardt, E TI Taxonomy and distribution of Gomphonema subtile Ehrenberg (Bacillariophyceae) and six related taxa SO Fottea PY 2015 BP 27 EP 38 VL 15 IS 1 DI 10.5507/fot.2015.003 DE Bacillariophyceae; diatom morphology; Gomphonema; new species; distribution; taxonomy; ultrastructure AB This paper reports on Gomphonema subtile and related taxa which have been classified as varieties so far and for which the shape of the headpole has been considered to be extremely variable. In literature they are described as cosmopolitan. However, the shape of G. subtile proved to be quite constant and specimens with less inflated headpoles represent separate species with limited distribution. G. subtile and G. sagitta, together with related diatoms like G. cathedrale, G. maclaughlinii and G. subsagitta form a group which is distributed in holarctic regions. In tropical regions similar species like G. pantropicum or G. pseudosubtile occur. All the mentioned taxa are described in detail and for most of them SEM-images are presented for the first time. G. pseudosubtile and G. subsagitta are described as new species. G. pantropicum is a new name for G. subtile var. malayense which is raised to species rank. In addition a few similar diatoms from tropical regions are discussed briefly. ER