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The genus Vanoverberghia currently includes three species namely V. sepulchrei and V. rubrobracteata from the Philippines and V. sasakiana from Taiwan. New material targeting the Alpinia eubractea clade of the tribe Alpinieae was used to test the monophyly of Vanoverberghia. A combined analysis of the ITS and trnK/matK regions reveals that these three species form a strongly supported monophyletic clade with Alpinia diversifolia and Alpinia vanoverberghii. The morphological descriptions of all species were updated after examining recent collections and comparing with types and protologues. The original description of A. diversifolia did not include information on the flowers which are described here. The morphology of A. diversifolia and A. vanoverberghii is for most parts in accordance with the previous perception of the genus but a few characters are added and a recircumscription of Vanoverberghia is subsequently provided here. Vanoverberghia diversifolia is reinstated and A. vanoverberghii is combined in Vanoverberghia. Furthermore, collections from northern Luzon documents the presence of V. sasakiana and all species of Vanoverberghia thus occur in the Philippines. A key to the five species is provided including a comprehensive taxonomic revision and designation of three lectotypes.

BackgroundThe Philippine archipelago is globally one of the most important model island systems for studying evolutionary processes. However, most plant species on this archipelago have not yet been studied in sufficient detail. The main aim of this study is to unravel the evolutionary history and biogeographic relationships of the Philippine members of the pantropical genus Ixora.ResultsThe complex plastid and nuclear divergence patterns in Philippine Ixora, documented using tree and network approaches, reveal a highly dynamic evolution in Ixora, involving several phases of radiation and recolonization. Philippine Ixora comprises at least five lineages, of which one is most closely related to species from Wallacea, and the remaining four to species from Asia.ConclusionsOur study highlights the importance of Philippine species for understanding phytogeographic patterns in the Indomalayan-Australasian eco-region. The overall genetic differentiation, as well as the incongruence between genealogies based on the biparentally inherited nucleome and the maternally inherited plastome in Ixora, reflect the complex tectonic history of the Philippine archipelago. The Ixora lineage related to Wallacean species supports the delimitation of different ecozones along Huxley’s line, because it is absent from Palawan. The remaining four lineages are all allied with Asian taxa, reflecting several waves of colonization. Close relationships between some widespread Philippine species and locally adapted narrow endemics suggest that the widespread, genetically diverse species act as pools for the formation of new species in a process of ongoing speciation. Our results suggest that the species concepts of some of the more widespread taxa need to be revised.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-017-0974-3) contains supplementary material, which is available to authorized users.

Two new species of Ixora are described from the provinces of Palawan and Samar, Philippines: I. alejandroi and I. reynaldoi. The two new species are compared mostly with other species of the genus from the Philippines and neighbouring Asian countries. Ixora alejandroi is characterized by its elongated cyme with congested secondary axes, reddish-brown corolla, stigmatic lobes shortly cleft in the middle, round at tip; while I. reynaldoi is easily recognised by its pseudanthium-type, 9-15 flowered inflorescences, long bracteoles (3.5-8 mm long), and keeled, foliaceous calyx lobes (8-10 mm long). The conservation status of each species is proposed, using IUCN Criteria.