After Froese & Pauly, 2001 [“The Fishbase”]

<==o Hippocampus (merihevoset; seahorses) [Nelson: 25] [Fishbase: 32]
   |-- †H. ramulosus
   |-- H. abdominalis Lesson, 1827 (Big-belly seahorse)
   |-- H. algiricus Kaup, 1856 (West African seahorse)
   |-- H. angustus Günther, 1870 (Narrow-bellied seahorse)
   |-- H. antiquorum (lyhytkuonomerihevonen)
   |-- H. barbouri Jordan & Richardson, 1908 (Barbour's seahorse)
   |-- H. bargibanti Whitley 1970 (Pygmy seahorse)
   |-- H. borboniensis Duméril, 1870 (Réunion seahorse)
   |-- H. breviceps Peters, 1869 (Short-head seahorse)
   |-- H. camelopardalis Bianconi, 1854 (Giraffe seahorse)
   |-- H. capensis Boulenger, 1900 (Knysna seahorse)
   |-- H. comes Cantor, 1850 (Tiger tail seahorse)
   |-- H. coronatus Temminck & Schlegel, 1850
   |-- H. erectus Perry, 1810-11 (Lined seahorse)
   |-- H. fisheri Jordan & Evermann 1903 (Fisher's seahorse)
   |-- H. fuscus Rüppell, 1838 (Sea pony)
   |-- H. guttulatus Cuvier 1829 (täplämerihevonen; Long-snouted seahorse)
   |-- H. hippocampus (Linnaeus, 1758) (Short-snouted seahorse)
   |-- H. histrix Kaup, 1856 (Thorny seahorse)
   |-- H. ingens Girard, 1858 (Pacific seahorse)
   |-- H. jayakari Boulenger 1900 (Jayakar's seahorse)
   |-- H. kelloggi Jordan & Snyder, 1901 (Great seahorse)
   |-- H. kuda Bleeker, 1852 (Spotted seahorse)
   |-- H. lichtensteinii Kaup, 1856 (Lichtenstein's Seahorse)
   |-- H. minotaur Gomon, 1997 (Bullneck seahorse)
   |-- H. mohnikei Bleeker, 1854 (Japanese seahorse)
   |-- H. reidi Ginsburg, 1933 (Longsnout seahorse)
   |-- H. sindonis Jordan & Snyder, 1901 (Dhiho's seahorse)
   |-- H. spinosissimus Weber, 1913 (Hedgehog seahorse)
   |-- H. subelongatus Castelnau, 1873 (West Australian seahorse)
   |-- H. trimaculatus Leach, 1814 (Longnose seahorse)
   |-- H. whitei Bleeker, 1855 (White's seahorse)
   |-- H. zebra Whitley, 1964 (Zebra seahorse)
   `-- H. zosterae Jordan & Gilbert, 1882 (Dwarf seahorse)

Reference(s):