The sad story of Agaricus rhacodes/rachodes: Why would an orthographical error with limited current use become accepted through conservation?

The spelling rachodes used by Vittadini in 1833 for a new species of Agaricus has often been considered a correct- able orthographical error for rhacodes. Use of the original spelling has however been occasional and was recently promoted by Vellinga and coworkers. The arguments used to support this practice, especially developed by Vellinga and Pennycook, when proposing conservation of rachodes in 2010 are refuted. It is shown that it is philologically illogical to assume an adjective rachodes could have been created, while the existing rhacodes was obviously meant. The use of the two spellings presented by Vellinga and Pennycook is shown to be incomplete. The conclusion is that rachodes should be corrected under Art. 60.1 to rhacodes, the spelling used for every other organism with that epithet, and that this correction is far more universal, including outside Europe, than the usage claimed for justifying a conservation of rachodes. The expenditure of energy caused by the Vellinga and Pennycook proposal shows that new ways to handle orthography of scientific names should be explored.