Abstract
Stemonoporus Thw. is the most species-rich (27 species) endemic dipterocarp genus in Sri Lanka. All its members are categorized as highly threatened or threatened in the IUCN Red Data Book. The existing classifications of the genus are primarily based on traditional taxonomic methods using a limited number of collected material and sometimes mainly on herbarium specimens. A recent study carried out in order to evaluate the species limits of Stemonoporus strengthens its position as the most species-rich endemic dipterocarp genus in Sri Lanka. However, there are no phylogenetic studies being carried out on this important genus. The aim of the study was to construct the phylogeny of the genus Stemonoporus , using morphological and phytochemical data. Specimens of all representative taxa were sampled from different geographical locations. A total of 170 specimens were collected and six individuals per taxon were examined. Cladistic analysis was performed based on morphological and phytochemical data extracted from specimens collected from different geographical locations and herbarium specimens. Combined analysis of morphological and phytochemical data suggests that all the species except for Stemonoporus wightii form a monophyletic group with strong bootstrap support of 82%. The strict consensus tree of the combined analysis identifies eight monophyletic groups within the genus Stemonoporus . S. wightii was resolved as the basal taxon of the genus. The identified 27 species are supported as monophyletic groups. Keywords: Dipterocarpaceae, morphological data, phylogeny, phytochemistry, Stemonoporus. doi:10.4038/jnsfsr.v36i4.266 Journal of the National Science Foundation of Sri Lanka 36 (4) 281-297
Highlights
Despite the relatively small size of 65,000 square kilometers, Sri Lanka harbours over 4,100 flowering plant species where over a quarter of these species are considered endemic to the country[1]
Combined analysis of morphological and phytochemical data suggests that all species except for S. wightii form a monophyletic group with strong bootstrap support of 82%
S. gracilis, S. elegans, S. lancifolius, S. nitidus and S. leavifolius are held together in the monophyletic group (D) and this group is strongly supported with 63% bootstrap
Summary
Despite the relatively small size of 65,000 square kilometers, Sri Lanka harbours over 4,100 flowering plant species where over a quarter of these species are considered endemic to the country[1]. Notwithstanding the relatively small size, Sri Lanka has a varied climate and topography, which has resulted in a rich biodiversity and today the island is considered one of the most biologically diverse areas in South Asia. Dipterocarpaceae, which forms a very closely-knit family, exhibits high endemism in Sri Lanka. Stemonoporus Thw. is the most species-rich endemic dipterocarp genus in Sri Lanka[2], and is of special interest with its unique characteristics and vulnerable position. The distinctive feature of Stemonoporus is the stamens that form a distinctive cone-like structure around the style (Figure 1).
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