Typification of Colletonema viridulum with the correct name for Frustulia erifuga and the description of a new Frustulia species (Amphipleuraceae, Bacillariophyta)

The historic material of Colletonema viridulum from Falaise, France, has been investigated and compared with samples containing Frustulia erifuga and F. torfacea. Colletonema viridulum is considered to be the original material for F. erifuga, and comparison of both populations showed that C. viridulum is conspecific with the larger morphotype I of F. erifuga. Morphological analysis, using both LM and SEM observations of F. torfacea, described in 1853, did not reveal any morphological difference with C. viridulum. Consequently, the latter name should be accepted, in accordance with the priority rule of ICN, as the legitimate name for C. viridulum and F. erifuga. The smaller morphotype II of F. erifuga has enough morphological differences from C. viridulum to justify its recognition as a distinct species, described here as new: Frustulia subtorfacea Van de Vijver, Juttner & Kusber, sp. nov. All populations are illustrated with LM and SEM images and their morphology is discussed.