Manticores

[Cassiopeia]

Hm, well a whole new bunch is certainly not there. I managed to get 3 now, but I think one was one that I didn't kill earlier because it came with a bunch of those nasty slimes. And then I found two more somewhere, but only after running through the entire area again, and most monsters that I encountered were no Manticores.

[Indinera]

I'd say you get 4-5 new ones but I didn't count exactly.
They pop up to give a second chance for players to complete manticore-involving sidequests, iirc.