Rhizoctonia cornigera (Bourdot) Zmitr. Biol. Bull. Rev. 14 (Suppl. 1): S33. 2024. Basionym: Corticium cornigerum Bourdot, Rev. Sci. Bourbonnais Centr. France. 35 (1): 15. 1922. Synonyms: Ceratobasidium cornigerum (Bourdot) D.P. Rogers, Stud. Nat. Hist. Iowa Univ. 17 (1): 5. 1935. Rhizoctonia cerealis E.P. Hoeven, Netherlands J. Pl. Pathol. 83 (5): 191. 1977, nom. inval. (Table 3). Ceratorhiza cerealis (E.P. Hoeven) R.T. Moore, Mycotaxon 29: 94. 1987, nom. inval. (Table 3). Ceratobasidium cereale D.I. Murray & Burpee, Trans. Brit. Mycol. Soc. 82 (1): 172. 1984. Type citation: ‘ Vere et aestate, ad caules putrescentes Helianthi tuberosi, Saint-Priest-en-Murat. ‘[‘Spring and summer, on putrescent stems of Helianthus tuberosus, Saint-Priest-en-Murat’]. Roberts cites the collection ‘Allier, St. Priest, on rotting stalks of Helianthus tubersosus, 13 May 1913, H. Bourdot 9355 PC’ as holotype. ITS barcode: AJ301903 (R). UNITE 1.5 % SH: n/a. Alternative markers: ATP6 = DQ301576; RPB2 = DQ301707; TEF1 = DQ301645. Notes: Refer to notes for R. ramicola and R. lantanae-camarae. The type of R. cornigera has not been sequenced. Oberwinkler et al. (2013) note that Cb. cornigerum is a broadly circumscribed taxon with no clear preference with respect to host or nutritional mode. The taxon is likely a species complex which contains several distinct taxa. Sequences from a CBS culture (CBS 132.82) identified as Cb. cornigerum in the analyses of Oberwinkler et al. (2013) generated by Gónzalez et al. (2001) were selected as representative sequences in this study. The synonymy of R. cerealis with R. cornigera follows Roberts (1999). Bondartseva & Zmitrovich (2024) transferred Cb. cornigerum to Rhizoctonia and noted (p. S33) that “If synonymy of Ceratobasidium cornigerum with Rhizoctonia goodyerae-repentis or Rh. fragariae is confirmed by modern methods for assessing taxonomic distance, one of these names should be used in the application to this species. If all three names are synonyms, the priority should be given to Rh. goodyerae-repentis.” However, we note that R. fragariae is an invalid name (Table 3), and R. goodyerae-repentis is considered a name of uncertain application (see notes under R. fusispora; Table 4).

Published as part of O'Donnell, R. P., Linde, C. C. & May, T. W., 2025, Rise up, Rhizoctonia: moving to one fungus, one name in the Ceratobasidiaceae (Agaricomycetes, Cantharellales), pp. 285-325 in Persoonia 54 (1) on page 303, DOI: 10.3114/persoonia.2025.54.09, http://zenodo.org/record/17127619