Rickenellla swartzii (Fr.) Kuyp., comb. nov. — Agaricus swartzii Fr., Obs. mycol. 1: 90. 1815 (basionym). This species has been known thus far as Rickenella setipes (Fr.: Fr.) Raithelhuber. However, the original diagnosis of Agaricus setipes (Fries, 1818: 162) clearly refers to another species, as A. setipes was characterized as follows: pileus 5—8 mm broad, campanulato-convex; stipe very long, 85—100 mm, setaceous; lamellae greyish; strongly resembling Agaricus corticola Pers.: Fr. As far as I can ascertain this protologue refers to a species of Mycena. The misapplication of the name Agaricus setipes might have arisen when Fries (1873: pl. 75 f. 4) published an illustration of an unnamed variety of A. setipes, which undoubtedly represents Rickenella swartzii. This unnamed variety was later (Fries, 1874: 164) called A. setipes var. acrocyaneus.