• Didymium H.A. Schrader, 1797
• Didymium anellus Morgan, 1894
• Didymium angularisporum J. Matsumoto, 1999
• Didymium annulisporum H.W. Keller & Schokn., 1989
• Didymium anomalum Sturgis, 1913 accepted as Didymium sturgisii Hagelst., 1937
• Didymium applanatum Nann.-Bremek., 1971
• Didymium aquatile Gottsb. & Nann.-Bremek., 1971
• Didymium atrichum Henney & Alexop., 1980
• Didymium bahiense Gottsb., 1968
• Didymium balearicum Ing, 2000
• Didymium canariense Ing, 2000
• Didymium chondroderma de Bary & Rostaf., 1872 accepted as Diderma chondrioderma (de Bary & Rostaf.) G. Lister, 1925
• Didymium chrysosporum T.N. Lakh. & Mukerji, 1979
• Didymium cinereum (Batsch) Fr., 1829 accepted as Physarum cinereum (Batsch) Pers., 1794
• Didymium circumscissile K.D. Whitney & L.S. Olive, 1983
• Didymium clavodecus K.D. Whitney, 1980
• Didymium clavus (Alb. & Schwein.) Rabenh., 1844
• Didymium columella-cavum Hochg., Gottsb. & Nann.-Bremek., 1989
• Didymium comatum (Lister) Nann.-Bremek., 1966
• Didymium complanatum (Batsch) Rostaf., 1874 accepted as Didymium serpula Fr., 1829
• Didymium congestum Berk. & Broome, 1850 accepted as Physarum didermoides (Ach. ex Pers.) Rostaf., 1875
• Didymium connatum Peck, 1874 accepted as Physarum notabile T. Macbr., 1922
• Didymium contextum (Pers.) Fr., 1818 accepted as Physarum contextum (Pers.) Pers., 1801
• Didymium crassicolle Ing, 1982
• Didymium crustaceum Fr., 1829
• Didymium delhianum T.N. Lakh. & Mukerji, 1979
• Didymium dictyopodium Nann.-Bremek. & Y. Yamam., 1986
• Didymium difforme (Pers.) Gray, 1821
• Didymium disciforme Kowalski & T.N. Lakh., 1973
• Didymium dubium Rostaf., 1875
• Didymium effusum (Link) Fr., 1815 accepted as Didymium squamulosum (Alb. & Schwein.) Fr., 1818
• Didymium elegantissimum Massee, 1892
• Didymium eremophilum M. Blackw. & Gilb., 1980
• Didymium eximuum Peck, 1879
• Didymium farinaceum Schrad., 1797 accepted as Didymium melanospermum (Pers.) T. Macbr., 1899
• Didymium flavicomum (Berk.) Massee, 1892 accepted as Physarum flavicomum Berk., 1845
• Didymium floccoides Nann.-Bremek. & Y. Yamam., 1987
• Didymium floriforme (Bull.) Schrad., 1797 accepted as Diderma floriforme (Bull.) Pers., 1794
• Didymium globosum (Pers.) Chevall., 1826 accepted as Diderma globosum Pers., 1794
• Didymium haretianum T.N. Lakh. & Mukerji, 1979
• Didymium hemisphaericum (Bull.) Fr., 1829 accepted as Diderma hemisphaericum (Bull.) Hornem., 1829
• Didymium ilicinum Ing ined.
• Didymium inconspicuum Nann.-Bremek. & D.W. Mitch., 1989
• Didymium iridis Fr., 1829
• Didymium karstensii Nann.-Bremek., 1964
• Didymium laccatipes J. Matsumoto, 1999
• Didymium lateritium Berk. & Broome, 1873 accepted as Physarum lateritium (Berk. & Ravenel) Morgan, 1896
• Didymium laxifilum G. Lister & J. Ross, 1943
• Didymium lenticulare K.S. Thind & T.N. Lakh., 1969
• Didymium leucopus (Link) Fr., 1829 accepted as Physarum leucopus Link, 1809
• Didymium listeri Massee, 1892
• Didymium macrospermum Rostaf., 1874
• Didymium marineri G. Moreno, Illana & Heykoop, 1989
• Didymium martinii (T.N. Lakh.) H. Neubert, Nowotny & K. Baumann, 1995
• Didymium megalosporum Berk. & M.A. Curtis, 1873
• Didymium melanospermum (Pers.) T. Macbr., 1899
• Didymium mexicanum G. Moreno, Lizárraga & Illana, 1996
• Didymium michelii Lib., 1832 accepted as Diderma hemisphaericum (Bull.) Hornem., 1829
• Didymium minus (Lister) Morgan, 1894
• Didymium muscorum T.N. Lakh. & Mukerji, 1976
• Didymium nigripes (Link) Fr., 1829
• Didymium nigrisporum Nann.-Bremek., Mukerji & Pasricha, 1984
• Didymium nivicola Meyl., 1929
• Didymium nullifilum (Kowalski) M.L. Farr, 1982
• Didymium ochroideum G. Lister, 1931
• Didymium oculatum C. Lippert, 1894 accepted as Colloderma oculatum (C. Lippert) G. Lister, 1910
• Didymium orthonemata H.W. Keller & T.E. Brooks, 1973
• Didymium ovoideum Nann.-Bremek., 1958
• Didymium parietinum Schrad., 1797 accepted as Orbicula parietina (Schrad.) S. Hughes, 1951
• Didymium perforatum Yamash., 1936
• Didymium pertusum Berk., 1836
• Didymium projectile T.N. Lakh. & Mukerji, 1979
• Didymium pseudocolumellum H.Z. Li, Yu Li & Q. Wang, 1996
• Didymium pusillum Berk. & M.A. Curtis, 1873 accepted as Physarum pusillum (Berk. & M.A. Curtis) G. Lister, 1911
• Didymium reticulatum Rostaf., 1873 accepted as Diderma effusum (Schwein.) Morgan, 1894
• Didymium rubropus G. Moreno, A. Castillo & Illana, 1996
• Didymium rugulosporum Kowalski, 1969
• Didymium saturnus H.W. Keller, 1970
• Didymium serpula Fr., 1829
• Didymium simlense T.N. Lakh. & Mukerji, 1979
• Didymium sinuosum (Link) Durieu & Mont., 1848 accepted as Physarum bivalve Pers., 1795
• Didymium spumarioides Fr., 1818 accepted as Diderma spumarioides (Fr.) Fr., 1829
• Didymium squamulosum (Alb. & Schwein.) Fr., 1818
• Didymium sturgisii Hagelst., 1937
• Didymium subreticulosporum Oltra, G. Moreno & Illana, 1996
• Didymium synsporon T.E. Brooks & H.W. Keller, 1973
• Didymium testaceum Schrad., 1797 accepted as Diderma testaceum (Schrad.) Pers., 1801
• Didymium tigrinum Schrad., 1797 accepted as Lepidoderma tigrinum (Schrad.) Rostaf., 1873
• Didymium trachysporum G. Lister, 1922
• Didymium tubicrystallinum Nann.-Bremek. & R.L. Critchf., 1988
• Didymium tubulatum E. Jahn, 1919
• Didymium tussilaginis (Berk. & Broome) Massee, 1892
• Didymium vaccinum (Durieu & Mont.) Buchet, 1920
• Didymium verrucosporum A.L. Welden, 1954
• Didymium xanthopus Fr., 1829 accepted as Didymium iridis Fr., 1829