Watch List notes:

Gallienus. A.D. 253-268. AE antoninianus (22.1 mm, 3.65 g, 5 h). Antioch mint, struck A.D. 262-264. GALLIENVS AVG, radiate and cuirassed bust right / ROMAE AETERNAE, Roma seated left on shield, holding Victory and spear, star above. Göbl 1613b var; RIC 654 var. Choice EF, black patina with sandy highlights. Rare variety. 

Neither Göbl or RIC list this obverse legend. Coinproject has an example that is listed as "Celator's error, the obverse legend should read GALLIENVS P F AVG."