ABSTRACT. – The fossil diatom Aulacoseira bellicosa (Héribaud) Simonsen is represented solely by resting spores; valves of the vegetative chain cells have not been preserved. The morphology of these spores from Late Pliocene maar sediments in southern France (Nogaret, south of Massif Central) is described using light and scanning electron microscopy. A comparison is made with literature data on similar spores. The number of areolae in 10 μm and its narrow range differ significantly from that of spores produced by Aulacoseira skvortzowii/islandica refuting a possible synonymy. Presumed non-French records of A. bellicosa most likely pertain to different taxa.