Abstract
Cocconeis scutellum var. ornata Grunow (1868) was originally described and illustrated in Grunow (1862) as Rhaphoneis marginata Grunow, and later illustrated by Grunow in Van Heurck (1880). Several further illustrations were produced by diverse authors, i.e., drawings and photographs from light microscopy and more recently using the scanning electron microscope (SEM), yet all done without checking the holotype. Material from a small historical mica-slide from the Grunow collection in Vienna, capsule N° 131–6, marked as containing C. scutellum var. ornata, was examined with the SEM and given a new status for this taxon, renamed as Cocconeis pseudornata Riaux-Gobin, Igersheim, Ector et Witkowski stat. et nom. nov. Herein, remarks are provided for the intricate history of the latter taxon. Cocconeis interrupta Grunow, mentioned by Grunow in his accession book as present in sample 131, is examined with the SEM and an emended description is provided.