Kovacs suggests Mallus. Cilicia seems likely, in view of the size and elements of design and inscriptions. Mallus later used a Pompeian era, starting in 68/7 BC, so year 48 would be 21/20 BC. However it cannot be excluded that there is another numeral after HM. The coin published as S-4016A has a similar portrait (perhaps Tiberus?); but, as pointed out there, the style of portrait seems different from other examples of Julio-Claudian portraiture.