According to the latest missions FAQ, martial arts can be taken as specializations for the skills they are listed under from the table on page 135 of run and gun. This table does not have several of the styles. Does that mean these styles cannot be taken as specializations? The missing styles are:
aikido
arnis de mano
capoeira
chakram fighting
jeet kune do
knight errant tactical
lone star tactical
ninjutsu
okichitaw
whip fighting
wildcat