Here are the units I am missing:
Slave (First left - Top row): Acquired upon city capture via events
Engineer (2nd left -Top row)
Citizen (3rd left - Top row): Used to expand the new colonies and perhaps some other uses.
Colonist (4th left - Top row): The only unit allowed to found a new city.
Latin Spearman (4th left - 3rd row): I may use this slot for something else, but if you fancied making an updated unit be my guest
Phoenician Hoplite (1st right - 3rd row)
Recruiter (2nd left - Sixth row): For bribing barbarian units
Spy/Envoy (3rd left - Sixth row): I could combine this unit with the recruiter?
Trader (4th left - Sixth row)
Merchant (5th left - Sixth row)
Some of the units I picked originally were selected for their artistic merits and are not vital for gameplay. I am still fiddling around with the units, but it looks like there are plenty of suitable Hoplites and other units to pick from. I may have to swap a few shields around and so forth before the final selection is complete.