Trebonianus Gallus, Tarsos, Cilicia, AE30

AV KAI G OVIBION TPIBW GALLON, radiate draped cuirassed bust right,
P-P across fields, countermark A in circular incuse on face.
TAPCOV MHTROPOLEOC, Perseus standing facing, head left, holding 
statue of Apollo Lykeios, A M K - B G across fields.

SNG Levante 1176; SNG France 1789

I have found 3 other examples of this countermark, all on coins 
from Mallos and stamped obtrusively on the face of Otacilia Severa 
(SNG France 1933. c/m ref Howgego 748), Valerian I (SNG Lev 1298) and the female bust of an autonomous 
coin, time of Trajan Decius (SNG Lev 1287 on wildwinds. 
c/m ref Howgego 664). There seems to be confusion over the 
Howgego reference. I found no other examples from Tarsos. I read 
a theory (source forgotten) that the 'A' stood for Aemelian, but 
the presence of the countermark on a coin of Valerian I would 
seem to disprove this and instead suggest a date of sometime 
after A.D 260.

Contributed by David Lowe, Feb. 2012.