herculeus, Mytilus [ Mytilus galloprovincialis Lamarck, 1819] (Figures 34M, N)

1884h: 6 [XXXI: 665]—available name

Type material. MCZR –M–9788 —2 sh + 1 v dx “ Myt. Herculeus di Sciacca. ”

MCZR–M–9688 —2 sh “Sciacca”, “ Mytilus herculeus Monts. grande esemplare ‘specimen maximum’ di Sciacca (Sicilia)”.

Type locality. Described from Sciacca (Sicily).

Remarks. Introduced as Mytilus galloprovincialis var. “ herculea ”, the name M. herculeus was raised to the status of species in subsequent works of Monterosato (1891 a: 97, note; 1915: 10). It is a giant form of M. galloprovincialis Lamarck, 1819 . Recorded by MolluscaBase (2018) as a synonym of Mytilus galloprovincialis Lamarck, 1819 .

hyalinus, Mytilus (Dacrydium) [ Dacrydium hyalinum (Monterosato, 1875)] (Figures 34O, P)

1875b: 10 [XIII: 236]—available name

Type material. MCZR –M–13973 —20 sh + 13 v “ Mytilus hyalinus Monts ”// 1 sh + 2 frg glued on thin cardboard, from “Messina”// 40 sh + 55 v + 4 frg from Palermo (= “P”, marked on the cork cap). Label on the bottom: “Myt. (Dacrydium) hyalinus Monteros. Palermo 40— 190 m.”

Type locality. Described from Palermo (Sicily) and other localities in the Mediterranean Sea, and Atlantic ?

Remarks. We follow the currently accepted opinion, that Mytilus hyalinus is available from Monterosato (1875b:

10), where size and shape are referred as diagnostic with the Atlantic Dacrydium vitreum (Møller, 1842), also considering the previous (Monterosato 1872b: 18) more detailed description of the Mediterranean form given by Monterosato. Ockelmann (1983: 120) studied specimens “from Monterosato’s own material” (Palermo), and recorded among them two specimens with several embryos inside (yet he did not report the whereabout of such possible type material). A valve of a further specimen originating from Monterosato in the Locard coll. (MNHN) was figured by Salas (1996: 52, fig. 92). Recorded by MolluscaBase (2018) as Dacrydium hyalinum (Monterosato, 1875) .

solidus, Mytilaster [ Mytilaster solidus Monterosato, 1883 ex H. Martin ms.] (Figures 35A, B)

1872b: 18 [VI: 100]—nomen nudum

1883a: 89 [XXXa: 603]—available name

Type material. MCZR –M–9552 —4 sh “Mod. solida Martin ms. Etang d’Engrenier d. Martin” MCZR –M–9531 —2 sh “ M. solidus C. di Prov. a.”

Type locality. Described from Martigues (France), and Palermo (Sicily).

Remarks. Despite the species having been discussed and/or figured by several authors (e.g., Locard, 1889: 155– 158, pl. V, fig. 9; B.D.D., 1890: 149–150, pl. 29, figs 11–14; Bogi et al., 1985: 25; 26, fig. 2; Giannuzzi–Savelli et al., 2001: 111, figs 178–181), its actual identity is still unclear and has been interpreted in quite diverging ways. The whole genus Mytilaster Monterosato, 1883, needs a careful revision. Recorded by MolluscaBase (2018) as Mytilaster solidus Monterosato, 1883 .