Note To Self: When considering the issue of L. Manlius Torquatus below (111 BC according to Mattingly), don’t forget that there are earlier Italic precedents for the reverse design, such as the AE quinrunx of Larinum above, dated by HN Italy to c. 210-175 BC.
You will want to order from ILL the relevant literature on Larinum (listed in HN Italy) and look for other similar Italic imagery.
Notice how the Torquatus coin even places all three elements of the legend in a similar location to that of the Larinum coin. His name for the ethnic, EXSC for the five pellets, and then, most strikingly, the Q for the V behind the riders head. [See three images down for a specimen of the quinrunx showing the V.]
The obverse of the above Larinum specimen looks more like a Minerva than an Ares in the Corinthian helmet. HN Italy queries lists as “Mars(?)”. Other specimens are more ambiguous or masculine:
But then see these long necked specimens (1) and (2)… The four specimens in the ANS seem very masculine indeed, especially the ‘fat necked’ SNGANS.1.131 and SNGANS.1.132.
Update 26/11/2013: Just adding this glass paste for comparison. It is dated by the Thorvaldsens Museum to the republican period. This rider doesn’t have the same helmet but otherwise shares many design elements right down to the the shield details.
They also given this a republican date:
Second update 27 February 2014: The coinage of Tarentum (Taras) also needs to brought into discussion (esp. HN Italy 1013):
Most of the rider imagery from Tarentum has the shield behind the rider, making this type stand out. Even here, the horse is rendered differently from above imagery, but it is certainly in the same visual repertoire.
Also see this newer post for comparative evidence.