• Acus Catesby, 1771 (unaccepted) [Family: Lepisosteidae, Phylum: Chordata]
• Acus Chen, Yang & Wilson, 1989 accepted as Neoacus Dmitriev, 2020 [Family: Achilidae, Phylum: Arthropoda]
• Acus Gray, 1847 accepted as Oxymeris Dall, 1903 [Family: Terebridae, Phylum: Mollusca]
• Acus Müller, 1766 accepted as Belone Cuvier, 1816 [Family: Belonidae, Phylum: Chordata]
• Acus Müller, 1774 accepted as Belone Cuvier, 1816 [Family: Belonidae, Phylum: Chordata]
• Acus Plumier in Lacepède, 1803 accepted as Sphyraena Artedi in Röse, 1793 [Family: Sphyraenidae, Phylum: Chordata]
• Acus Swainson, 1839 accepted as Entelurus Duméril, 1870 [Family: Syngnathidae, Phylum: Chordata]
• Acus Tsao & Zhao, 1974 † [Family: , Phylum: Animalia incertae sedis]
• Acus Valmont de Bomare, 1791 accepted as Syngnathus Linnaeus, 1758 [Family: Syngnathidae, Phylum: Chordata]
• Ancus Putzeys, 1866
• Arcus A.P. Olshtynskaja, 1978 † accepted as Fossilarcus S. Blanco, 2020 † [Family: Hemiaulaceae]
• Arcus Hong, 1983 † [Family: Paraxymyiidae]
• Asacus accepted as Asaccus Dixon & Anderson, 1973
• Ascius DeLong, 1943
• Asius Tosquinet, 1903 (uncertain)
• Nascus Watson, 1893