Floral morphology and phylogenetic analysis in crossostylis (Rhizophoraceae)

Floral morphology in all ten species of Crossostylis, one of the inland genera of Rhizophoraoeae and is distributed in the South Pacific Islands was studied to increase our knowledge on floral features of individual species as well as on relationships among the species. Flowers of Crossostylis, unlike those of the other Rhizophoraceae, always have semi-inferior ovaries and entire petals, but are diversttied concerning the number and arrangement of stamens and carpels the presence or absenoe ef staminodia, sexuality and the structure of nectaries. Despite some doubt of the presence of apomorphies restrieted to the whole genus, we tentatively defined Crossostylis by a combination of the presence of the semi-inferior ovary, entire petals and arillate seeds, and then performed cladistic analysis on the basis of 24 floral and other morphological characters and with Carallia and Gynotroches as outgroups. Our phylogenetic analysis suggested that the species of Ctossostylis are divided into two monophyletic greups : one comprising six species distrtibuted in the Solomon Islands, Vanuatu and the Fiji Islands, and the other comprising four species distributed in New Caledonla and Polynesia. The genus Crossostylis J.R. et G.Forst. is one of ten or eleven inland genera of Rhizophoraceae and comprises ten or more species, which are distributed in the South Pacific Islands including New Caledonia, the Fiji Islands, Vanuatu, the Solomon Islands, Samoa, the Society Islands and the Marquesas Islands.