Helmut wrote:

the right of this Arcidae is Scapharca inaequivalvis (Bruguière, 1789) and
it is indeed an
immigrant from the Indopacific to the Mediterranean ans specially to the
Adriatic.
My mother found her first specimens of this species in 1978 at Jesolo Lido
near Venice.
They live burried in the sand and also nearby the beach and people collect
them to
eat. It is a very common species. A wellknown synonym is Scapharca cornea
(Reeve, 1844). They have a dark periostracum. If you can send a photo I
probably can
say if it is this species. Hope this helps.
with best shelling greetings and a Merry Christmas and a Happy New Year
Helmut from Innsbruck

Scapharca cornea is quite different from S. inaequivalvis. When the S.
inaequivalvis first appeared in the Adriatic sea the name S. cornea was
used, bult later on it was determined as S. inaequivalvis. S. cornea has a
thicker shell and the ribs are more granulated. Nowadays S. inaequivalvis is
common in the Adriatic sea but it is an immigrant there.
Martin C. Cadee, The Netherlands