The Celt-Iberian Portuguese and Galiceans were not under the Mohammadan yoke, at least not compared to Castile, Aragon and Andalus. As a result, they may not have felt the need to invent something that did not resemble al Oud after their liberation from the seven century long Mohammadan occupation, so they may have stayed with the pear-shaped single bout for that reason, instead of going for the double-bouted vihuelan shape.
Of course, our terminology is all messed up. What most folks called guitars should probably be called vihuela. :-) To get on or off this list see list information at http://www.cs.dartmouth.edu/~wbc/lute-admin/index.html
