Thalassonerita megastoma Moroni, 1966

Kiel, Steffen, Sami, Marco & Taviani, Marco, 2023, Mollusks (Gastropoda, Bivalvia) from Miocene cold-seep deposits in northern Italy: revisions and additions, European Journal of Taxonomy 910, pp. 115-160 : 129-130

Thalassonerita megastoma Moroni, 1966

Fig. 6A–B

Nerita (Thalassonerita) megastoma Moroni, 1966: 71 , pl. 1.

Material examined

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 .

Remarks

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).

Stratigraphic and geographic range

Middle to Upper Miocene, northern Italy.

Figures

Fig. 6. Neritimorpha Golikov & Starobogatov, 1975 and Caenogastropoda Cox, 1960 from the Calcari a Lucina seep deposits in northern Italy. A–B. The phenacolepid (Neritimorpha) Thalassonerita megastoma Moroni, 1966, Le Colline (MSF 1223), internal mold showing columellar muscle scars. C–E. The elachisinid (Caenogastropoda) Laeviphitus sp. C. Small specimen with preserved protoconch, from Ca’ Rovereti (NRM Mo 204837). D. Close-up on transition between proto- and teleoconch, from Ca’ Rovereti (NRM Mo 204838). E. Tall specimen (MSF 1204) from Le Colline. F–G. Naticidae indet. sp. 1. F. Shell embedded in rock matrix, from Castiglion dei Pepoli (MGGC 22304). G. Operculum (MSF 1218). H. Naticidae indet. sp. 2 from Guzzano (MGGC 22305). I–K. Pisanianura? pusilla Bellardi 1872, from Castel di Casio. I. Specimen with remains of siphonal canal and shell sculpture (MGGC 22306). J. Small, internal mold (MGGC 22307). K. Large specimen with preserved shell (MGGC 22308). L. Semicassis aff. reticulata (Bellardi & Michelotti, 1840), Castiglion dei Pepoli (MGGC 22310).