Background In September 2015, an at the time undescribed, autotrophic taxon was discovered in the western English Channel (station L4) and also in the eastern English Channel and Celtic Sea during the Polarstern Cruise PS95 a month later. Subsequent investigations revealed further extensive records (going back to 1992) at stations in the English Channel and the southern North Sea (e.g. Helgoland Roads and Sylt Roads time series stations). Stations in the Northern North Sea have not recorded this distinct taxon. With the available records and crucially, the accompanying image metadata, we are able to chart a clear distribution record with occurrences being restricted to the southern North Sea and English Channel. Methods The biological data shown are from Lugol-fixed Utermöhl counts on Lugol-peserved samples and investigations of live and Formalin-fixed net hauls (20 µm mesh size). All image material shown is available in the online repository Planktonnet (http://planktonnet.awi.de). Results We report the distribution, based on geo-referenced image records of an easily recognisable, yet taxonomically uncertain, autotrophic organism. Conclusions Distribution patterns of the unidentified autotrophic taxon suggests entry of this taxon into/out of the North Sea via the English Channel. Further investigations providing image-documented information over several years is clearly necessary to clarify its dynamics and ecological characteristics.