Nomenclatural notes on some European marine bivalve species

Some nomenclatural issues affecting European species are discussed. The following taxa are treated under ICZN Art. 23.9, with the required references provided:
- Mytilus variabilis Krauss, 1848 (currently Brachidontes variabilis (Krauss, 1848)) is declared nomen protectum against the senior homonym Mytilus variabilis Fischer von Waldheim, 1807, declared nomen oblitum. The still earlier name Brachidontes ustulatus (Lamarck, 1819), currently used as the valid name for a native species of Western Australia, should take precedence over B. variabilis (Krauss, 1848) were it demonstrated that it is the same biological species, but in the current state of knowledge it is proposed to keep them separate.
- Modiola nigra Gray, 1824 (currently Musculus niger (Gray, 1824)) is declared nomen protectum against the senior synonym Mytilus discors svecicus Fabricius, 1788, declared nomen oblitum.
- Ostrea flexuosa Poli, 1795 (currently Flexopecten flexuosus (Poli, 1795)) is declared nomen protectum against the senior synonym Ostrea coarctata Born, 1778, declared nomen oblitum.
- Chama aculeata Poli, 1795 (currently Centrocardita aculeata (Poli, 1795)) is declared nomen protectum against the senior homonym Chama aculeata Ström, 1768, declared nomen oblitum, thereby making valid the current usage and avoiding the need for using the junior synonym Centrocardita elegans (Requien, 1848).
- Solen marginatus Pulteney, 1799 is declared nomen protectum against the senior synonyms Hypogaea tentaculata Poli, 1791, Solen rotundatus Spengler, 1794 and Solen gladius Röding, 1798, all declared nomina oblita.
The following cases are discussed but do not meet the conditions for application of ICZN Art. 23.9:
- Anadara polii (Mayer, 1868) is in prevailing usage over Anadara gibbosa (Reeve, 1844) but the latter name has been employed once in the XX century so must be used.
- Chama gryphina Lamarck, 1819 (currently Pseudochama gryphina (Lamarck, 1819)), is not a junior synonym of Chama cornuta Dillwyn, 1817. The latter name is made an objective synonym of Chama bicornis Linnaeus, 1758 by lectotype designation.
- Venus rhomboides Pennant, 1777 (currently Polititapes rhomboides (Pennant, 1777)) should not be superseded by Venus virginea Linnaeus, 1767. The extant types of Venus virginea are here figured. Two of them belong to the species currently known as Venerupis geographica (Gmelin, 1791) and one to Venerupis aurea (Gmelin, 1791). Therefore, the suppression of the name virginea seems the best outcome.
- Ensis arcuatus (Jeffreys, 1865) and Solen ensis major Chenu 1843 are both held as junior synonyms of Ensis magnus Schumacher, 1817, therefore the name Solen siliqua var. arcuata Jeffreys, 1865 does not need to be declared nomen protectum.
- Neaera bicarinata Jeffreys, 1882 does not need to be declared a nomen protectum against Neaera striata var. bicarinata Jeffreys, 1876, which is a nomen nudum, therefore not available.