Tigrans and the dargon races in general have been stated in the past to be void mutated animals.  Of note is that do to hybridization there is a degree of parallel anatomy between the assorted hominid races. Given that elves are seen as archaic, the closest to the Seraph, mayhaps once the tigrans were uplifted into an agile state, the internal parallels occurred as they were efficient for the shape desired. The Woathar could be one of the earlier groups of elves, closer to the Seraph directly. An ancient strain that changed, but still divided from the original ancestor. Or the inverse, and Woathar are a recent mutation relatively.

Orcs are recent manifested to their current state, yet already existed in the archaic ages of the Elven Empire. Woathar as a relatively recent manifestation could be the result of sustained mutation amid a populace, suiting their environ better. Not the result of offshoot from shared ancestors, but the propogation of the Seraph evolutionary path, toward a more suitable species.