Carthaginian Shields
The evidence for the shields of Carthaginian citizen troops is summarised in "Armies of the Macedonian and Punic Wars", by Duncan Head.
It depends on the date of your army. The Sacred Band at Krimisos in 341 BC are described (in Plutarch's "Life of Timoleon") as wearing iron cuirasses and bronze helmets, with huge round white leather shields - probably plain white, with no blazons. Then there is a big gap lacking in reliable evidence, until the Third Roman-Punic War, when Strabo describes Carthage manufacturing thureoi - oval, Celtic- or Roman-style, shields.
Between these points, Greek-style hoplite-shields do appear in Carthaginian art, so it is probable that the citizen troops carried these until they adopted the oval shield - whenever that was. Silius Italicus' epic Latin poem the Punica describes troops "from Carthage" in Hannibal's army as barefoot, wearing red, and armed with swords and round leather shields - he uses "parma", the term used for the shields of Roman velites and cavalry, and thus probably implying a fairly light shield. But it is far from clear whether this is a realistic description or, like many of Silius' details, a fanciful poetic embroidery; and if it is a realistic description, it is also not clear who is being described.
Finally, the Chemtou monument is a Numidian royal construction of the 2nd century BC probably commemorating victory over the Carthaginians in the Third Punic War, when Numidia was a Roman ally. This depicts large, unblazoned, oval shields, and round shields with varied blazons in Greek style, including an eye, Herakles' club, Zeus' thunderbolt, and Athene's aigis. It is possible that one or both of these shield-styles copies Carthaginian equipment taken as trophies in this final war; but then again, they may be Hellenising artistic convention.
For Carthaginian citizen troops of the first and second Roman-Punic wars, I would be inclined to use hoplite shields, painted white, with individual blazons mixing Greek emblems and motifs taken from Carthaginian art such as horses, palm-trees, the "Hand of Baal" and the "Sign of Tanit". But that is largely guesswork.
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