FleaMan is a rather new name, too.
There seem to be four species of jumping nasty short monster:
1. Hunchbacks (CV1, CV3, X68000)
2. SabreTooth Rabbits (Akumajo Densetsu, Super Castlevania IV)
3. FleaMen (DraculaX, SotN, AoS, DoS, PoR)
4. Creepers (Belmonts' Revenge)
Hunchbacks are more like tiny zombie-looking Igors, with bald heads and hair on their upper neck (sort of like what the CryptKeeper looks like, only short and, well, hunchbacked)
SabreTooth Rabbits appear as counterparts to Hunchbacks in Akumajo Densetsu, and in Super Castlevania IV and do the exact same part.
Fleamen (or Rippers, for the dagger-throwing versions) seem to be mutants, and can appear in large numbers. I suppose harpies can harvest them off of a WakWak tree and divebomb 'em in the proper zones, but I agree with DragonSlayr81 in that the tree probably only starts to spawn them when it senses some kind of moving object nearby (could be a Belmont, could be a Harpy).
Creepers come out of holes on the wall. I think it's possible that they can come out of the earth like in "The Gate", or they're root-tree versions of Fleamen.