• "Lower Heterobranchia"
• [unassigned] Caenogastropoda (temporary name)
• [unassigned] Cardiidae (temporary name)
• [unassigned] Cephalaspidea (temporary name)
• [unassigned] Cladobranchia (temporary name)
• [unassigned] Decapodiformes (temporary name)
• [unassigned] Enteropneusta (temporary name)
• [unassigned] Euheterodonta (temporary name)
• [unassigned] Euthyneura
• [unassigned] Heterobranchia (temporary name)
• [unassigned] Muricidae (temporary name)
• [unassigned] Naticidae (temporary name)
• [unassigned] Neogastropoda (temporary name)
• [unassigned] Neomphaloidea (temporary name)
• [unassigned] Seguenzioidea (temporary name)
• [unassigned] Solenogastres (temporary name)
• [unassigned] Stylommatophora (temporary name)
• [unassigned] Trochidae (temporary name)
• [unassigned] Vetigastropoda (temporary name)
• [unassigned] Mytilidae (temporary name)
• [unassigned] Pectinidae (temporary name)
• “Montereina” sensu Dayrat, 2010 (temporary name)
• “Montereina” concinna (Alder & Hancock, 1864) represented as Discodoris concinna (Alder & Hancock, 1864)
• “Montereina” erubescens (Bergh, 1884) represented as Discodoris erubescens Bergh, 1884
• “Montereina” punctifera (Abraham, 1877) represented as Peltodoris punctifera (Abraham, 1877)
• Aaptos Gray, 1867
• Aaptos aaptos (Schmidt, 1864)
• Aaptos papillata (Keller, 1880)
• Aartsenia Warén, 1991
• Aartsenia candida (Møller, 1842)
• Abaconia Clench, 1938 accepted as Litiopa Rang, 1829
• Abaconia naufraga (Clench, 1938) accepted as Litiopa melanostoma Rang, 1829
• Abarenicola Wells, 1959
• Abarenicola claparedei (Levinsen, 1884) accepted as Abarenicola claparedi (Levinsen, 1884)
• Abarenicola claparedi (Levinsen, 1884)
• Abarenicola pusilla (Quatrefages, 1866)
• Abavopsis Salvini-Plawen, 1973
• Abavopsis latosoleata (Salvini-Plawen, 1973)
• Abditoconus Voight, 2019
• Abditoconus anselli (Harvey, 1996)
• Abditoconus brava (Romano, Pérez-Portela & D. Martin, 2014)
• Abditodentrix Patterson, 1985
• Abditodentrix rhomboidalis (Millett, 1899) accepted as Tortoplectella rhomboidalis (Millett, 1899)
• Abedinium Loeblich & A.R.Loeblich, 1966
• Abedinium dasypus (Cachon & Cachon-Enjumet) Loeblich Jr & Loeblich III, 1966
• Aberrantospermata Jondelius, Wallberg, Hooge & Raikova, 2011
• Abietinaria Kirchenpauer, 1884
• Abietinaria abietina (Linnaeus, 1758)
• Abietinaria filicula (Ellis & Solander, 1786)
• Abietinaria fusca (Johnston, 1847)
• Abietinaria interversa (Pictet & Bedot, 1900)
• Abietinaria pulchra (Nutting, 1904)
• Abludomelita Karaman, 1981
• Abludomelita aculeata (Chevreux, 1911)
• Abludomelita gladiosa (Spence Bate, 1862)
• Abludomelita obtusata (Montagu, 1813)
• Abludomelita richardi (Chevreux, 1900)
• Abollifer Vørs, 1992
• Abollifer prolabens Vørs, 1992
• Abothrium Van Beneden, 1871
• Abothrium gadi Van Beneden, 1871
• Abra Lamarck, 1818
• Abra alba (W. Wood, 1802)
• Abra fragilis Risso, 1826 accepted as Abra prismatica (Montagu, 1808)
• Abra longicallis (Philippi, 1844) accepted as Abra longicallus (Scacchi, 1835)
• Abra longicallis var. americana Verrill & Bush, 1898 accepted as Abra longicallus (Scacchi, 1835)
• Abra longicallus (Scacchi, 1835)
• Abra longicallus americana Verrill & Bush, 1898 accepted as Abra longicallus (Scacchi, 1835)
• Abra milaschevichi Nevesskaja, 1963 accepted as Abra prismatica (Montagu, 1808)
• Abra nitida (O. F. Müller, 1776)
• Abra ovata (Philippi, 1836) accepted as Abra segmentum (Récluz, 1843)
• Abra prismatica (Montagu, 1808)
• Abra profundorum (E. A. Smith, 1885)
• Abra renieri (Bronn, 1831) accepted as Abra alba (W. Wood, 1802)
• Abra segmentina H. Adams & A. Adams, 1856 accepted as Abra segmentum (Récluz, 1843)
• Abra segmentum (Récluz, 1843)
• Abra tenuis (Montagu, 1803)
• Abra tenuis lorenzoi Cecalupo, Buzzurro & Mariani, 2008 accepted as Abra tenuis (Montagu, 1803)
• Abralia Gray, 1849
• Abralia (Asteroteuthis) Pfeffer, 1908
• Abralia (Asteroteuthis) veranyi Rüppell, 1844
• Abralia jattai Pfeffer, 1912 accepted as Abraliopsis (Abraliopsis) morisii (Verany, 1839)
• Abralia lonnbergi Pfeffer, 1912 accepted as Abraliopsis (Abraliopsis) morisii (Verany, 1839)
• Abralia mediterranea Pfeffer, 1912 accepted as Abraliopsis (Abraliopsis) morisii (Verany, 1839)
• Abralia megalops Verrill, 1882 accepted as Ancistrocheirus lesueurii (d'Orbigny [in Férussac & d'Orbigny], 1842)
• Abralia veranyi (Rüppell, 1844) represented as Abralia (Asteroteuthis) veranyi Rüppell, 1844
• Abraliopsis Joubin, 1896
• Abraliopsis (Abraliopsis) Joubin, 1896
• Abraliopsis (Abraliopsis) morisii (Verany, 1839)
• Abraliopsis morisii (Vérany, 1839) represented as Abraliopsis (Abraliopsis) morisii (Verany, 1839)
• Abraliopsis pfefferi Joubin, 1896 accepted as Abraliopsis (Abraliopsis) morisii (Verany, 1839)
• Abramis Cuvier, 1816
• Abramis ballerus (Linnaeus, 1758) accepted as Ballerus ballerus (Linnaeus, 1758)
• Abramis bjoerkna (Linnaeus, 1758) accepted as Blicca bjoerkna (Linnaeus, 1758)
• Abramis brama (Linnaeus, 1758)
• Abramis sapa (Pallas, 1814) accepted as Ballerus sapa (Pallas, 1814)
• Absidia Tiegh., 1878
• Absidia spinosa Lendn., 1905
• Abudefduf Forsskål, 1775
• Abudefduf luridus (Cuvier, 1830) accepted as Similiparma lurida (Cuvier, 1830)