Colobostylus nuttii H.A. Pilsbry, 1903 Jamaica
Tropidophora nyassanum E.A. Smith Malawi
Rolleia oberi G.T. Watters & G. Duffy,2010 Dominican Republic
Wrightudora obesa (C. de la Torre& P. Bartsch, 1941) Cuba
Chondropoma obesum (K.T. Menke, 1830) Cuba15,7 mm
Chondropoma obesum hershei C. de la Torre& P. Bartsch, 1938 Cuba15 mm
Bermudezia obliterata (C. de la Torre& P. Bartsch, 1941) Cuba
Annularia obsoleta (C. de la Torre& P. Bartsch, 1941) Cuba26 mm
Tropidophora obsoleta (J.B.P.A. Lamarck, 1822) Madagascar26 mm
Opisthosiphon obtectum C. de la Torre& J. Henderson, 1920 Cuba
Bermudezsiphona obturatum (C. de la Torre& J. Henderson, 1920) Cuba
Bermudezsiphona obturatum sulcosum C. de la Torre& P. Bartsch, 1941 Cuba
Ligatella obtusa (L. Pfeiffer, 1862) Zanzibar Island
Rhytidopoma occidentale C. de la Torre& P. Bartsch, 1941 Guadeloupe, Saint Martin
Tropidophora occlusa (O.A.L. Mörch, 1852) Madagascar30,9 mm
Opisthocoelicum occultum (C. de la Torre& J. Henderson, 1921) Cuba
Chondropoma oculeum G.T. Watters & G. Duffy,2010 Dominican Republic
Pomatias olivieri J.G.F. de Charpentier Israel17 mm
Chondropoma olssoni H.A. Pilsbry, 1933 Dominica
Opisthocoelicum opisthocoele C. de la Torre& P. Bartsch, 1941 Cuba
Tropidophora oppessulata E. Fischer-Piette, F. Blanc& F. Salvat, 1969 Madagascar, Diego Suarez
Cyclotopsis orchidae (K.C. Emberton, 2003) Madagascar
Weinlandipoma orcutti (P. Bartsch, 1946) Haiti
Dioscopoma ornatum (H.H. Godwin-Austen,1881) Yemen, Socotra8,5 mm
Choanopomops osberti (H.B. Tristram, 1861) Guatemala
Chondrothyrella ottonis (L. Pfeiffer, 1846) Cuba
Chondropoma oxytremum (J. Gundlach in L. Pfeiffer, 1860) Cuba
Annularisca pallens C. de la Torre& P. Bartsch, 1941 Cuba
Pomatias palmensis (T.V. Wollaston, 1878) Canary Islands
Opisthosiphon palmeri C. de la Torre& P. Bartsch, 1941 Trinidad and Tobago13,5 mm
Parachondria papyracea (C.B. Adams, 1850) Jamaica
Gundlachtudora paradoxa G.T. Watters, 2013 Dominican Republic
Opisthocoelicum paradoxum (C. de la Torre& J. Henderson, 1921) Cuba
Tudora paraguanensis Hovestadt, 2016
Opisthosiphon paredonense C. de la Torre& J. Henderson, 1920 Cuba10,8 mm