Islands of the Aegean Sea, Cyclades, Keos, Karthaia(?), Stater late 6th century BC, unpublished

Islands of the Aegean Sea. Cyclades. Keos, Karthaia (?). AR Stater (16mm, 8.86 g), late 6th century BC.
Obverse: Kantharos // Reverse: Quadripartite incuse square with pellet in each quarter.

Apparently unpublished in the standard references.

Toned, flan cut in antiquity, otherwise Good Very fine