| Neosiphonia howei Skelton & G.R. South, 2007 |
| Neosiphonia japonica (Harv.) M.S. Kim & I.K. Lee, 1999 |
| Neosiphonia saccorhiza (F.S. Collins & Herv.) J.M.C. Nunes & S.M. Guimarães, 2010 |
| Neosiphonia sertularioides (Gratel.) K.W. Nam & P.J. Kang, 2012 |
| Neosiphonia simplex (Hollenberg) Y.P. Lee, 2008 |
| Neosiphonia sphaerocarpa (Børgesen) M. Kim & Lee, 1999 |
| Neosiphonia tepida (Hollenberg) Guimaraes & Fujii, 2004 |
| Neosiphonia tongatensis (Harv. ex Kütz.) M. Kim & Lee, 1999 |
| Ohelopapa F. Rousseau, Martin-Lescanne, Payri & L. Le Gall, 2017 |
| Ohelopapa flexilis (Setchell) F. Rousseau, Martin-Lescanne, Payri & L. Le Gall, 2017 |
| Ophidocladus Falkenb., 1897 |
| Ophidocladus herposiphonioides A.B. Joly & Cordeiro, 1963 |
| Ophidocladus simpliciusculus (P. Crouan & H. Crouan) Falkenb., 1897 |
| Osmundaria J.V. Lamour., 1813 |
| Osmundaria obtusiloba (C. Agardh) R.E. Norris, 1991 |
| Osmundea Stackh., 1809 |
| Osmundea blinksii (Hollenberg & I.A. Abbott) K.W. Nam, 1994 |
| Osmundea crispa (Hollenberg) K.W. Nam, 1994 |
| Osmundea estebaniana (Setchell & N.L. Gardner) J.N. Norris, 2014 |
| Osmundea lata (M. Howe & W.R. Taylor) Y. Yoneshigue-Valentin, Fujii & C.F. Gurgel, 2003 |