Did the Siamese derive from a different species of wildcat?

Apparently scientists (Kratochvil and Kratochvil - 1976) produced a research document that suggests that the Siamese cat originated from a different species of wildcat than the other domestic cats except for the Persian.

They argue that the domestic cat is derived from the wildcat Felis silvestris lybica (true, the African wildcat and in fact the European wildcat) and that the Siamese derived from another subspecies of "Felis lybica". This is wrong it seems because they make reference to a subspecies of Felis lybica. There is no subspecies of Felis lybica. The full scientific name is as mentioned Felis silvestris lybica.

However the African wildcat is also bundled together as one species with the Asian wildcat (Felis silvestris ornata) and it is possible therefore that the Siamese cat derives from the Asian wildcat as the eastern boundary of the range of the Asian wild cat is nearer Siam now Thailand than that of the African or European wildcat. The Siamese cat comes originally from Siam as you no doubt know.