they haven't been removed, but if you're looking for them try top right edge of the map, generally by the time I reach monsters I can scout out a dullahan. I usually find the elves near the dullahans, but iirc it's advisable to have the elf companion with you.  The mountain boss should have a little mountain icon on her location again towards the top right. Lastly for the wasp and generally all of the latest updated characters, if you scroll your map to the top there should be two branches that lead up off the map, one should take you to the giantess/goddess and the other takes you to a region that's full of the new encounters like the wasp, thief, etc.