Fig. 6A–B
Nerita (Thalassonerita) megastoma Moroni, 1966: 71, pl. 1.
ITALY – Emilia-Romagna • 5 specs; Caselle C; NRM Mo 204846. – Tuscany • 3 specs; Le Colline; MSF 1203 (W = 7 mm), MSF 1220 (H = 7.6 mm), MSF 1223 (W = 15.2 mm) • 6 specs; same collection data as for preceding; NRM Mo 204845.
Thalassonerita megastoma has been reported and at times figured from various Calcari a Lucina sites of the Romagna Apennines (Moroni 1966; Taviani 1994, 1996, 2001, 2011; Sami & Taviani 2015, 2019; Kiel et al. 2023). Specimen MSF 1223 from Le Colline shows scars of the left and right columellar muscles, consistent with the anatomical sketch of the closely related extant species Thalassonerita naticoides (Clarke, 1989) provided by Warén & Bouchet (1993: fig. 2). Thalassonerita naticoides is a very common species at methane-seeps in the Gulf of Mexico and the Caribbean Sea (Clarke 1989; Warén & Bouchet 1993; Olu et al. 1997; Amon et al. 2017).
Middle to Upper Miocene, northern Italy.
Subclass Caenogastropoda Cox, 1960
Order Littorinimorpha Golikov & Starobogatov, 1975
Family Elachisinidae Ponder, 1985