Figure 8. Historical biogeographical hypothesis of the Pseudopontiinae + Dismorphiinae, with dispersal and extinction events optimized to reconcile the area cladogram. Letters designate speciation events: a, vicariance between Pseudopontiinae (Africa) and Dismorphiinae (South America), following the final break-up of Western Gondwana (Late Cretaceous); b, long-distance dispersal of the ancestor of Dismorphiinae from northern South America to northern Africa (Late Cretaceous), followed by allopatric speciation of Leptidea in northern Africa (Late Cretaceous). Numbers designate major biogeographical events: 1, dispersal (range expansion) of the ancestor of Leptidea from northern Africa to Eurasia, following contact of Africa with Eurasia (early Tertiary); 2, extinction (range contraction) of Leptidea in northern Africa following formation of the Sahara Desert (Quaternary). Once Leptidea reached Eurasia it colonized much of the Palaearctic, the Neotropical Dismorphiinae subsequently spread into Central America, whereas the Pseudopontiinae contracted to central western Africa.