I want to see a really NICE Ariminum struck bronze. I have questions.
That warrior is he supposed to be a Colonist or a Gaul? Are there any ethnically identifying details. Is that a torque I see around the neck on a could of these specimens below? Does he have shaggy wild hair and a bit of a mullet? Maybe I’m just not convinced yet.
Really I’m just interested in how ‘Gallic’ the shield shape is to a Roman viewer and most of my evidence is much later.
The c. 120 BCE representations are v rectangular :
But the Caesarean era ones are pointy ish:
And all of this is to make up my mind if the quincunx of Ariminum is meant to have as its type specifically a ‘Gallic’ Shield? Or just… a shield? Is it marked or unmarked?
Molinari suggested to me that it was likely meant to be Gallic and now I’m thinking. And, as so often, I’m leaning to thinking she’s correct.
Gorini 2010 does not make ethnic claims. His relevant descriptions
“Scudo ovale”
“Guerriero andante a sinistra con scudo ovale, lancia e spada; all’esergo ARIMN”
Cf. for obverse of cast bronze:
“Testa maschile con bafi e torques di una divinità locale, forse Arimnus”
Liv Mariah Yarrow 
To keep things a muddle, the shield could be either Celtic or Roman, as both used an oblong with a barleycorn spine, and it was probably often hard to tell the two apart (although iconographically sometimes Celtic shields were portrayed at pointed or hexagonal, perhaps reflection actual variation, or perhaps to prevent confusion with the scutum. The bare head and lack of a tunic hem, however, might suggest a Gaul.