• Debesia O. Kuntze, 1891 accepted as Anthericum Linnaeus, 1753
• Reasia Gray in Todd, 1843 (uncertain)
• Rebecca J.C. Green in B. Edvardsen, W. Eikrem, J.C. Green, R.A. Andersen, S.Y. Moon-van der Staay & L.K. Medlin, 2000
• Rebelia Heylaerts, 1900
• Rebutia K. Schumann, 1895
• Reesia Ewart, 1913 accepted as Polycarpaea Lamarck, 1792
• Reessia C. Fisch, 1883
• Reevesia Lindley, 1827
• Reisia Handlirsch, 1909 † (uncertain) [Family: Protodonata (awaiting allocation)]
• Reisia Tomlin, 1929 † accepted as Closteroides Tomlin, 1929 † [Family: Neogastropoda (awaiting allocation)]
• Reissia Brundin, 1981 (uncertain) [Family: Chironomidae]
• Reissia Loeblich & Tappan, 1964 [Family: Cassidulinidae]
• Remesia Kettner, 1937 †
• Ressia Sinev, 1988 (uncertain)
• Retusia Beck, 1996 (uncertain)
• Reusia Duchaissing & Michelotti, 1860 accepted as Madracis Milne Edwards & Haime, 1849
• Reussia A.W. Dennstedt, 1818 accepted as Paederia Linnaeus, 1767 [Family: Rubiaceae]
• Reussia Duchassaing & Michelotti, 1860 accepted as Madracis Milne Edwards & Haime, 1849 [Family: Astrocoeniidae]
• Reussia Endlicher, 1836 accepted as Pontederia Linnaeus, 1753 [Family: Pontederiaceae]
• Reussia K.B. Presl in Sternberg, 1838 † (unaccepted) [Family: Osmundaceae]
• Reussia Maksimova, 1971 † accepted as Reussiana Snajdr, 1987 † [Family: Phacopida (awaiting allocation)]
• Reussia Maksimova, 1972 † accepted as Reussiana Snajdr, 1987 † [Family: Phacopida (awaiting allocation)]
• Reussia M'Coy, 1854 (uncertain) [Family: Crustacea (awaiting allocation)]
• Reussia Neviani, 1895 † [Family: Bryocryptellidae]
• Reussia Schwager, 1877 † accepted as Reussella Galloway, 1933 [Family: Reussellidae]
• Reyesia C. Gay, 1849?
• Reynesia Buckman, 1902 † (uncertain)
• Reyssia Gerken, 2018
• Rhebasia Jullien, 1882 † accepted as Ogiva Jullien, 1882 †
• Ribasia Ceballos, 1920 (uncertain)