Dipterocarpoideae, the largest sub-family of well-known plant family Dipterocarpaceae, dominates in South Asian rain forests. Although several previous studies addressed the phylogeny of the Dipterocarpaceae family, relationships among many of its genera from the Dipterocarpoideae sub-family are still not well understood. In particular, little is known about the relationships of the genera Vateriopsis , Stemonoporus , Vateria and inconsistence remains between phylogenetic results and taxonomic classifications of Shorea and Hopea species. We studied molecular phylogeny of the sub-family Dipterocarpoideae using the trnL-trnF spacer, trnL intron and the matK gene sequences of chloroplast DNA (cpDNA). This study is the first comprehensive phylogeny reconstruction for the sub-family Dipterocarpoideae based on cpDNA, as it includes most genera (14) and a large number of species (79) with most species endemic to Sri Lanka, as well as one species from Seychelles and one species from the genus Monotes from Madagascar. Phylogenetic trees were constructed using the Neighbor Joining (NJ) and Maximum Likelihood (ML) methods using combined set of sequences including all three cpDNA regions. The topologies of the NJ and ML trees were to a certain extent, consistent with the current taxonomy of Dipterocarpoideae based on morphology and with previous molecular phylogenies based on cpDNA. Furthermore, our results provided new evidence regarding the relationships of the following genera: Vateriopsis and Stemonoporus and about the validity of the previous morphology based classifications of Shorea species. In addition, the topology of our trees was consistent with the classification of Shorea species proposed by Maury (1978), Maury-Lechon (1979) and Symington (1943). Finally, our results provided evidence for the affinity of the genus Monotes to Asian Dipterocarpoideae rather than to Tiliaceae and indicated that it is a good candidate for outgroup species for future studies of the former sub-family.

The Dipterocarpaceae, a well-known tropical tree family of Asian rainforests, is the most dominant component of Sri Lankan rainforests. The origin of Sri Lankan Dipterocarpaceae and their relationship with other Asian members of the family are still unknown. We studied this relationship using chloroplast DNA nucleotide sequences. DNA sequences of trnL-trnF spacer and trnL intron regions from 27 Sri Lankan species, and 62 other species belonging to 14 genera were included in the study. The neighbor joining (NJ) tree was constructed using aligned sequences of both regions. Monotes madagascariensis was used as an out-group. The obtained result is, to a certain extent, consistent with the current morphology based on taxonomy of Dipterocarpaceae. The Sri Lankan endemic genus Stemonoporus formed a monophyletic clade. The other Sri Lankan species of Hopea, Dipterocarpus, Vatica, Cotylelobium, Vateria and most of Shorea formed separate groups on the phylogenetic tree. This may indicate that Sri Lankan Dipterocarpaceae evolved independently after Sri Lanka became geographically isolated from the Indo-Malaysian region.