Hi, I found this:

In a website offering different varieties of shell fish, they mention tellina:
http://www.specimenshells.net/1237.htm

You can also check this site with pictures:
http://www.users.bigpond.com/jandmgrist/Shells/Tellina_delto...

And in this one you can find a number of varieties of them:
http://www.serc.si.edu/sms/IRLSpec/Phyl_Mollus4.htm


Here you have other examples within contexts where "tellinas" is used:

Tellinas or sunset shells are tiny shellfish that live in the sands of
Camargue.
www.stratsplace.com/articles/provence2.html

The coastal waters of the Land of Valencia offer a wide variety of fish and seafood, and fishing has long been traditional in many seaboard villages. [...] Tellinas, steamed mussels, sardines, hake, red mullets, sole, and sea bass make many palates happy.
http://www.comunitat-valenciana.com/english/actividades/gast...

Buena suerte!