This coin is only known from one unique specimen in Paris. Its authenticity seems guaranteed by the accuracy of the Oscan language inscription, which at the time of its first documentation was not yet fully understood. Photos on the internet are hard to find. The wikipedia entry is okay. Heck, I’m impressed it has an entry or sub-entry. I’ve taken the image above from Wyler’s 2008 article.
Mostly I’m writing this post to make a note of Mattingly’s rather under-acknowledged theory that this is not a Social War coin at all, but a product of the Mithridatic Wars (2004: 189-192). The usual explanation is that the Italians copied the type from the bronze of Amisos:
And that thus it represents tangible proof of the suggestions in the literature that the Italians sought (and perhaps obtained?) support from Mithridates (Diod. 37.2.10; Athenaeus 5.213C). My enemy’s enemy is my friend, as they say. On Dionysus imagery during the Social War, see:
Pobjoy, M., ‘The First Italia’ in K. Lomas and E. Herring (eds.), The Emergence of State Identities in Italy in the First Millennium BC (London: Accordia Research Institute, 2000), 187-211.
Anyway, Mattingly focuses on this passage from Plutarch’s Lucullus:
Mithridates was now resolved upon the speediest possible flight, but with a view to drawing Lucullus away, and holding him back from pursuit, he dispatched his admiral, Aristonicus, to the Grecian sea. Aristonicus was just on the point of sailing when he was betrayed into the hands of Lucullus, together with ten thousand pieces of gold which he was carrying for the corruption of some portion of the Roman army.
He thinks that the Parisian specimen is one of these pieces of gold and that the Oscan was used to unsettle the Italian troops in Lucullus’ army and encourage them all the more to revolt.
This seems even more far fetched, than the Social War explanation. Really the problem comes down to there only being one of these gold coins. We have no comparative evidence or geographical data, let alone archaeological context. We remain in the realm of speculation. Anyway, just to make this post a little more complete, we should note that a similar bust of Dionysus does appear on the Italian’s silver coinage: