1. Species Hypnea alopecuroides Kützing
2. Species Hypnea anastomosans Papenfuss, Lipkin & P.C.Silva, 2002
3. Species Hypnea arbuscula P.J.L.Dangeard, 1953
4. Species Hypnea arenaria Kylin, 1938
5. Species Hypnea asiatica P.J.L.Geraldino, E.C.Yang & S.M.Boo, 2009
6. Species Hypnea brasiliensis P.B.Jesus, Nauer & J.M.C.Nunes, 2016
7. Species Hypnea bryoides Børgesen, 1943
8. Species Hypnea caespitosa P.J.L.Geraldino & S.M.Boo, 2010
9. Species Hypnea cenomyce J.Agardh, 1851
10. Species Hypnea ceramioides Kützing, 1849
11. Species Hypnea cervicornis J.Agardh, 1851
12. Species Hypnea charoides J.V.Lamouroux, 1813
13. Species Hypnea chordacea Kützing, 1847
14. Species Hypnea coccinea (Clemente) Cremades, 1990
15. Species Hypnea compressa Papenfuss, 1947
16. Species Hypnea congesta Papenfuss, 1947
17. Species Hypnea cornuta (Kützing) J.Agardh, 1851
18. Species Hypnea corona Huisman & Petrocelli, 2021
19. Species Hypnea davisiana P.B.Jesus, Lyra, J.M.C.Nunes & M.C.Oliveira, 2023
20. Species Hypnea divaricata (C.Agardh) Greville, 1830
21. Species Hypnea djamilae P.B.Jesus, Lyra, J.M.C.Nunes & M.C.Oliveira, 2023
22. Species Hypnea ecklonii Suhr, 1836
23. Species Hypnea edeniana F.Nauer, V.Cassano & M.C.Oliveira, 2014
24. Species Hypnea esperi Bory de Saint-Vincent, 1828
25. Species Hypnea evaristoae P.B.Jesus, Lyra, J.M.C.Nunes & M.C.Oliveira, 2023
26. Species Hypnea evermannii Setchell & N.L.Gardner, 1930
27. Species Hypnea filiformis (Harvey) Womersley, 1994
28. Species Hypnea flagelliformis Greville ex J.Agardh, 1851
29. Species Hypnea flava Nauer, Cassano & M.C.Oliveira, 2014
30. Species Hypnea flexuosa A.C.Brown & N.Jarman
31. Species Hypnea fruticulosa Kützing, 1849
32. Species Hypnea furnariana Cormaci, Alongi & Dinaro, 1993
33. Species Hypnea hamulosa (Esper) J.V.Lamouroux, 1813
34. Species Hypnea intricata Kylin, 1938
35. Species Hypnea japonica Tanaka, 1941
36. Species Hypnea johnstonii Setchell & Gardner, 1924
37. Species Hypnea krugiana Hauck, 1888
38. Species Hypnea multicornis (Montagne) Montagne, 1845
39. Species Hypnea musciformis (Wulfen) J.V.Lamouroux, 1813
40. Species Hypnea nidifica J.Agardh, 1852
41. Species Hypnea nidulans Setchell, 1924
42. Species Hypnea nigrescens Greville ex J.Agardh, 1851
43. Species Hypnea pannosa J.Agardh, 1847
44. Species Hypnea pectinella Børgesen, 1954
45. Species Hypnea platyclada Barreto de Jesus & Castro Nunes, 2013
46. Species Hypnea pseudomusciformis Nauer, Cassano & M.C.Oliveira, 2015
47. Species Hypnea ramentacea (C.Agardh) J.Agardh, 1876
48. Species Hypnea reptans Papenfuss, 1947
49. Species Hypnea rosea Papenfuss, 1947
50. Species Hypnea rugulosa Montagne, 1842
51. Species Hypnea schneideri Nauer, Cassano & M.C.Oliveira, 2019
52. Species Hypnea spicifera (Suhr) Harvey, 1847
53. Species Hypnea spinella (C.Agardh) Kützing, 1847
54. Species Hypnea stellulifera (J.Agardh) Yamagishi & Masuda, 2003
55. Species Hypnea tenuis Kylin, 1938
56. Species Hypnea unilateralis P.J.L.Dangeard, 1953
57. Species Hypnea vaga Kützing, 1863
58. Species Hypnea valentiae (Turner) Montagne, 1841
59. Species Hypnea variabilis Okamura, 1909
60. Species Hypnea viridis Papenfuss, 1947
61. Species Hypnea volubilis Searles, 1976
62. Species Hypnea wynnei Nauer, Cassano & M.C.Oliveira, 2016
63. Species Hypnea yamadae Tanaka, 1960
64. Species Hypnea yokoyana Nauer, Cassano & M.C.Oliveira, 2016
65. Species Hypnea arborescens P.L.Crouan & H.M.Crouan, 1865 accepted as Hypnea musciformis (Wulfen) J.V.Lamouroux, 1813 (synonym)
66. Species Hypnea armata (C.Agardh) J.Agardh, 1851 accepted as Hypnea spicifera (Suhr) Harvey, 1847
67. Species Hypnea aspera Kützing, 1868 accepted as Hypnea cervicornis J.Agardh, 1851
68. Species Hypnea boergesenii T.Tanaka, 1941 accepted as Hypnea cervicornis J.Agardh, 1851
69. Species Hypnea bourgesenii T. Tonaka accepted as Hypnea boergesenii T.Tanaka, 1941 accepted as Hypnea cervicornis J.Agardh, 1851 (misspelling)
70. Species Hypnea californica Kylin, 1941 accepted as Hypnea valentiae (Turner) Montagne, 1841
71. Species Hypnea conferta (Schousboe ex Montagne) Kützing, 1849 accepted as Gracilaria conferta (Schousboe ex Montagne) Montagne, 1846
72. Species Hypnea confervoides (C.Agardh) J.Agardh, 1842 accepted as Gracilariopsis longissima (S.G.Gmelin) Steentoft, L.M.Irvine & Farnham, 1995 (synonym)
73. Species Hypnea coulteri Harvey, 1851 accepted as Sarcodiotheca gaudichaudii (Montagne) P.W.Gabrielson, 1982
74. Species Hypnea cystoclonioides Sonder, 1855 accepted as Hypnea ramentacea (C.Agardh) J.Agardh, 1876
75. Species Hypnea divergens (C.Agardh) J.Agardh, 1842 accepted as Gracilaria divergens (C.Agardh) J.Agardh, 1847 (synonym)
76. Species Hypnea episcopalis J.D.Hooker & Harvey, 1847 accepted as Hypnea ramentacea (C.Agardh) J.Agardh, 1876
77. Species Hypnea esperii Suhr accepted as Hypnea esperi Bory de Saint-Vincent, 1828 (misspelling)
78. Species Hypnea fastigiata Harvey, 1863 accepted as Mychodea pusilla (Harvey) J.Agardh, 1872
79. Species Hypnea flexicaulis Y.Yamagishi & M.Masuda, 2000 accepted as Hypnea cervicornis J.Agardh, 1851
80. Species Hypnea fructiculosa Kutzing accepted as Hypnea fruticulosa Kützing, 1849 (misspelling)
81. Species Hypnea furcellata J.D.Hooker & Harvey, 1847 accepted as Trematocarpus concinnus (R.Brown ex Turner) De Toni, 1900
82. Species Hypnea harveyi Kützing, 1849 accepted as Hypnea spicifera (Suhr) Harvey, 1847 (synonym)
83. Species Hypnea hippuroides Kützing, 1868 accepted as Hypnea musciformis var. hippurioides (Kützing) Weber-van Bosse, 1928 (synonym)
84. Species Hypnea horrida (C.Agardh) J.Agardh, 1847 accepted as Endosiphonia horrida (C.Agardh) P.C.Silva, 1996
85. Species Hypnea marchantiae Setchell & N.L.Gardner, 1924 accepted as Hypnea cervicornis J.Agardh, 1851
86. Species Hypnea planicaulis Harvey, 1859 accepted as Calliblepharis planicaulis (Harvey) Kylin, 1932
87. Species Hypnea purpurascens (Hudson) Harvey, 1847 accepted as Cystoclonium purpureum (Hudson) Batters, 1902
88. Species Hypnea rangiferina (R.Brown ex Turner) Greville, 1830 accepted as Callophyllis rangiferina (R.Brown ex Turner) Womersley, 1973
89. Species Hypnea rigens Sonder, 1853 accepted as Hypnea ramentacea (C.Agardh) J.Agardh, 1876
90. Species Hypnea rissoana J.Agardh, 1842 accepted as Hypnea musciformis (Wulfen) J.V.Lamouroux, 1813
91. Species Hypnea saidana Holmes, 1896 accepted as Calliblepharis saidana (Holmes) M.Y.Yang & M.S.Kim, 2017
92. Species Hypnea secundiramea Montagne, 1842 accepted as Ochtodes secundiramea (Montagne) M.A.Howe, 1920
93. Species Hypnea seticulosa J.Agardh, 1851 accepted as Hypnea charoides J.V.Lamouroux, 1813
94. Species Hypnea simpliciuscula Okamura, 1895 accepted as Hypnea chordacea Kützing, 1847 (synonym)
95. Species Hypnea simpliuscula Okamura, 1895 accepted as Hypnea chordacea Kützing, 1847
96. Species Hypnea spicigera Harvey, 1849 accepted as Hypnea spicifera (Suhr) Harvey, 1847 (synonym)
97. Species Hypnea ustulata (Mertens ex Turner) Montagne, 1840 accepted as Caulacanthus ustulatus (Turner) Kützing, 1843 (synonym)
98. Species Hypnea valida J.Agardh, 1896 accepted as Hypnea ramentacea (C.Agardh) J.Agardh, 1876
99. Species Hypnea wurdemannii Harvey, 1853 accepted as Eucheuma isiforme (C.Agardh) J.Agardh, 1847 accepted as Eucheumatopsis isiformis (C.Agardh) Núñez-Resendiz, Dreckmann & Sentíes, 2019
100. Species Hypnea mamillosa Zanardini, 1843 (uncertain, uncertain taxonomic status subjected to verification)

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