The school textbook of my daughter (the textbook is written in German) describes the five kingdoms of life: prokaryota, plants, fungi, animals and "Ursprungliche Eukaryoten". These are defined as "single cell organisms with real nucleus and other specialized organoids, both autotrophs and heterotrophs". No Latin name is given.
I am somewhat confused, as I know that there are both multi and single cell varieties between algae, and these used to belong to even particular taxon within algae (a single cell Rhodella, for instance, not just belongs to plants but also specifically belongs to red algae). Also, there are unicellular fungi like yeast that used to be fungi (and, OK, protists used to be a separate group that probably also belongs to "Ursprungliche Eukaryoten"). Are they all pulled out of they groups into this new kingdom in this system?
The summary of the proposed classification schemes over history can be found at https://en.wikipedia.org/wiki/Kingdom_(biology)#Summary . Which scheme, if any does this taxon correspond? Is something missing in that table?
The textbook is Training Gymnasium - Biologie Mittelstufe Band 1, Harald Steinhofer (2013), ISBN 978-3-86668-709-7, seen here. The description in question is on the page 16.