Trachycystis iredalei H.B. Preston, 1912
Cavellia irregularis (H.H. Suter, 1890)
Climocella isolata J.F. Goulstone, 1997
Gyrocochlea iuloidea (E. Forbes, 1851)
Flammulina jacquenetta F.W. Hutton, 1883
Fectola jamiesoni F.M. Climo, 1978
Rotadiscus jamiesoni (F.M. Climo, 1978)
Setomedea janae J. Stanisic, 1990
Ptychodon janeirensis (K.H.J. Thiele, 1927)
Dentherona jemmysensis (C.J. Gabriel, 1947)
Cavellia jenniferae (FOSSIL) B.A. Marshall& T.H. Worthy, 2017 †
Fectola jessica (F.W. Hutton, 1883)
Protoflammulina johnsi F.M. Climo, 1971
Oreomava johnstoni (T. Iredale, 1933)
Costallodiscus kaikoura B.A. Marshall & G.M. Barker,2008
Climocella kaitaka J.F. Goulstone, 1996
Allodiscus kakano B.A. Marshall & G.M. Barker,2008
Lithocouperia kalkajaka Stanisic, 2016
Cralopa kaputarensis J. Stanisic, 1990
Canallodiscus karamea B.A. Marshall & G.M. Barker,2008
Afrodonta kempi (M. Connolly, 1925)
Rhophodon kempseyensis J. Stanisic, 1990
Rhophodon kemseyensis J. Stanisic, 1990
Climocella kenepuruensis (H.H. Suter, 1909)
Allocharopa kershawi (W.F. Petterd, 1869)
Rotacharopa kessneri J. Stanisic, 1990
Pernagera kingstonensis (C.M.D.E. Legrand, 1871)
Serpho kivi (J.E. Gray, 1843)
Pilsbrycharopa kobelti (O. Böttger, 1908)
Vatusila kondoi G.A. Solem, 1983
Paryphantopsis koragae J. Slapcinsky, 2005
Semperdon kororensis (R.H. Beddome, 1889)
Kubaryiellus kubaryi (O.F. von Möllendorff,1900)
Mocella kuntzi G.A. Solem, 1960
Sinployea kusaieana G.A. Solem, 1983