As of Chapter 66 of the manga, the members of Peter's harem consist of 1 human, 2 ogres, 2 elves, 1 dwarf, 1 goblin, 2 orcs, 1 white tiger, 1 dragon, 1 halfling, and 1 succubus.
Therefore, in regards to future members of Peter's harem, which species should they hail from: a muscular amazoness, a valkyrie, a gothic vampire, a dark-skinned mummy, a zombie, a harpy, a cyclops, a jiang shi, or a flesh golem etc.?