According to Marine Fishes by Scott Michael, several anthias cannot be kept together. Bartlett's anthias (Pseudanthias bartlettorum ) can only have one male per tank and cannot be kept with any other Pseudanthias. Alot of the others say that one male should be kept with 8+ females in tank sized 135gal or larger. The Fathead Anthias (aka Hawkfish Anthias), Serranocirrhitus latus , can only be kept one per tank, unless a pair is obtained.
As far as will subspecies school together, I am not exactly sure, but it seems that unless you keep all females, males can only exist one per tank. Good luck finding out more info on these guys.
I hope this helps.