The mulefa is described as having a trunk, research into anatomy of elephants will give insight on how to draw the mulefas head. If the mulefa has a trunk, it is likely that it possesses a similar bone structure in it's head and face.
Mulefas are said to have a diamond shaped frame and do not have a backbone, they also move by hooking their front and rear legs into seed pods and pushing with their side legs. Their skeleton may resemble a motor cycle chassis. This is a good place to start figuring out the anatomy of a mulefa.