NOTHOFAGINEA Singer, Rev. Mycol. 15: 127. 1950.
NOTHOFAGINEA Singer var. CARMINEA Singer, Beih. Nova Hedwigia 29: 353. 1969.
NOTHOFAGINEA Singer form CARMINEA Singer, Rev. Mycol. 15: 448. 1950.
NOVISPORA Murrill, Mycologia 36: 309. 1944.
OBSCURIFORMIS Murrill, Lloydia 7: 312. 1944.
OBTECTA Singer, Bull. Soc. Mycol. France 55: 233. 1939.
OCCIDENTALIS (Singer) Singer, Lilloa 22: 705. 1949.
OCHRICOMPACTA Bills and Miller, Mycologia 76: 976, figs. 1, 8-11, 39. 1984.
OCHROLEUCOIDES Kauffman, Mycologia 9: 165. 1917.
OCHROLEUCIFORMIS Murrill, Lloydia 8: 267. 1983.
OCHROPHYLLA Peck, Annual Rep. New York State Mus. 50: 100. 1897.
OCHROSTRAMINEA Pegler in Pegler and Singer, Mycotaxon 12: 96. 1980.
OPERTA Burlingham, Mycologia 16: 18, pl. 4, fig. 2. 1924.
ORINOCENSIS Patouillard and Gaillard, Bull. Soc. Mycol. France 4: 18. 1888.
ORNATICEPS Burlingham, Mycologia 13: 130, pl. 7, fig. 2, fig. 4. 1921.
PACHYCYSTIS Singer in Singer et al. Beih. Nova Hedwidgia 77: 236. figs. 16, 17, pl. 18a. 1983.
PALUSTRIS Peck, Annual Rep. New York State Mus.. 53: 842. 1900.
PANTOLEUCA Singer, Sydowia 11: 239. 1957(1958).
PARTIROSEA Murrill, Lloydia 8: 268. 1945.
PARVULA Burlingham, N. Am. Fl. 9: 235. 1915.
PATRIOTICA Murrill, Mycologia 40: 635. 1948.
PAXILLOIDES Earle, Bull. New York Bot. Garden 2: 341. 1902.
PECKII Singer, Mycologia 35: 147. 1943.
PECTINATA Fr. subsp. PECTINATOIDES (Peck) Bohus and Babos, Ann. Hist. Nat. Mus. Hungary 52: 140. 1960.
PECTINATOIDES Peck, New York State Mus. Bull. 116: 43, pl. 105, figs. 6-10. 1907.