Systematics of Dombeyoideae (Malvaceae) in the Mascarene archipelago (Indian Ocean) inferred from morphology

<p class="rtejustify">The Mascarene Archipelago is characterized by remarkable fauna and flora, mainly due to its high rate of endemism. The Dombeyoideae Beilschm. is one of the most diversified groups of angiosperms in the Mascarenes with 22 species, 21 of which are endemic. We used parsimony analysis of morphological characters to examine the relationships between the endemic Dombeyoideae from the Mascarenes and the members of Dombeyoideae from Africa, Madagascar and Asia. A morphological matrix was created including 36 representative species and 42 characters. Among the most parsimonious trees (MPTs) those with the highest number of secondary homologies were identified. The Dombeyoideae from the Mascarenes are polyphyletic and split into nine clades. Trochetia appears monophyletic and more closely related to Eriolaena and Helmiopsis than to Dombeya. All Dombeya taxa are included in a clade together with Ruizia and Astiria, which makes Dombeya paraphyletic. In terms of breeding systems the Malagasy Dombeyoideae are hermaphroditic, whereas those of the Mascarenes are considered dioecious. The polyphyly of the Mascarene Dombeyoideae suggests that dioecy has been acquired several times. At least five colonization events from Madagascar to the Mascarene archipelago are inferred. The evolutionary history of two lineages of Mascarene Domeyoideae seems to be related to adaption to xeric habitats.</p>