Thyasira sp. 1

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 : 140-141

Thyasira sp. 1

Fig. 9A–B

Material examined

ITALY – Emilia-Romagna • 1 spec.; Castiglione dei Pepoli; MGGC 22311 (H = 12 mm) .

Description

Small, well-inflated, smooth, rounded-pentagonal shell, about as long as high, umbones elevated, blunt, slightly prosogyrate; posterior sulcus close to posterodorsal margin, deep, bordered distinct, roundtopped ridge; submarginal sulcus narrow; anterodorsal margin slightly concave

Remarks

The two species of Thyasira reported here are all small, poorly preserved, and represented by a single specimen each, making a robust identification difficult. They are placed in Thyasira due to their overall shape and size, and the presence of a shallow posterior sinus. Furthermore, Thyasira sp. 1 appears to have a submarginal sulcus. The two specimens differ in inflation and outline: Thyasira sp. 1 from Castiglione dei Pepoli is more globular than Thyasira sp. 2 from Casola; the latter is taller (it has a longer anterior margin) than Thyasira sp. 1 .

Stratigraphic and geographic range

Lower to Middle Miocene (Aquitanian to Langhian), northern Italy.

Figures

Fig. 9. Thyasirid bivalves from Calcari a Lucina seep deposits in northern Italy. A–B. Thyasira sp. 1, Castiglione dei Pepoli (MGGC 22311). C. Thyasira sp. 2, Casola (MGGC 22312). D–E. Channelaxinus? sp., Caselle A (NRM Mo 204840).