@nschwab Thanks for the suggestion. In some new identification books in German (Kosmos Handbuch Pilze, 2023; Die Pilze Deutschlands, 2021; e.g. ....), at "Wikipedia", at "123pilzsuche.de" ....) Neoboletus erythropus is also mentioned as the first name. And iNaturalist users very often use exactly these data sources.

I also agree with this taxon merge. I have been going around in circles reading the papers discussing the varying names, but the general view is that N. erythropus takes precedence. We have no idea if/when we will have an actual taxonomical resolution, and the current use of multiple synonyms on Inat is confusing for us all. In the UK we seem to have adopted N. praestigiator, but we can just as easily "unlearn" that. I vote for merging all with Neoboletus erythropus whilst we await an official taxonomy review.

A case which illustrates the problem https://www.inaturalist.org/observations/186540997