Beware of the fact that in taxonomical spheres you have "lumpers""and “splitters”, both camps living together happily ever after. If you use MO as a tool for mycofloristics, and not as a social game, you need some stability in the “naming” for your observations. In Entolomataceae we follow Largent’s works, in polypores sensu lato, Jim Ginns. Why do the MO naming experts mind, when they – I bet – have never seen the fungi whose names they are changing?
Claudopus byssisedus (Pers.) Gillet and Entoloma byssisedum (Pers.) Donk are both synonyms to each other. You can use either of them as Mushroom Observation names. For the names of our MO postings, we follow Largent DL. 1994. Entolomatoid fungi of the Pacific Northwest and Alaska. Mad River Press, USA. I do not know what the term “deprecated synonyms” means. There is no mention of deprecation, deprecating, etc. in the Code of Nomenclature. Get rid of the MO Name pages, they don’t make any sense. Adolf