Phylogenetic and phytogeographical relationships in Maloideae (Rosaceae) based on morphological and anatomical characters

Phylogenetic relationships among 24 genera of Rosaceae subfam. Maloideae and Spiraeoideae are explored by means of a cladistic analysis; 16 morphological and anatomical characters were included in the analysis. Published suprageneric classifications and characters used in these classifications are briefly reviewed. Additionally, some new features are here reported, such as seed shape, presence or absence of endosperm, and number of cell layers in the seed coat and in the endosperm. Parsimony analyses indicate that Eriobotrya and Rhaphiolepis form a well-supported clade that is the sister to the remainder of the subfamily. This result is in agreement with published ITS sequence data. Other clades are not supported, with the exception of the group Amelanchier-Peralaphyllum-Malacomeles. Results of several studies point toward North America as centre of origin for Maloideae, considering the distribution of closely related Spiraeoideae such as Vauquelinia and Lindleia. A non-metric multidimensional scaling analysis of Takhtajan's biogeographic regions was carried out using presence/absence of genera as characters. Eastern Asia is a centre of diversity from which the number of shared taxa decreases in several directions. This can be associated with the retreat of many taxa belonging to the Early Tertiary tropical-subtropical flora towards the refuges of China, Indochina and Malaysia, after wet-temperate forests were progressively transformed during the Neogene, which seems to be the case of Eriobotrya and Rhaphiolepis. Finally, Osteomeles and Chamaemeles were postulated as long-distance dispersion events while Hesperomeles could have originated in North America and migrated into north-western South America.