Phylogenetic relationships of Gordonia Ellis (Theaceae) species endemic to Sri Lanka

A study of the genus Gordonia Ellis was carried out using morphological data to determine the phylogenetic relationships of the four endemic species, Gordonia ceylanica Wight, G. elliptica Gardner, G. speciosa (Gardn.) Choisy, and G. dassanayakei Wadhwa et Weerasooriya. Vegetative and reproductive features were studied in detail from live and herbarium specimens in order to select characters and character states. The phylogenetic analysis was performed using PAUP* computer soft ware. The present analysis using 77 morphological characters recovered a strongly supported monophyletic genus with the endemic Gordonia species. Even though most of the past taxonomic treatments recognized G. ceylanica Wight and G. elliptica Gardner as two distinct species, both species did not receive any support as being monophyletic. G. speciosa (Gardn.) Choisy and G. dassanayakei Wadhwa et Weerasooriya were recovered as monophyletic groups. The study revealed several confusing character combinations that overlap among these species, especially between G. elliptica and G. ceylanica questioning their species limits. Therefore, this study emphasizes the necessity of carrying out further studies on species limits of Gordonia with more informative characters such as molecular data.

Keywords: Cladistics, Gordonia Ellis, monophyly, morphological data, Sri Lanka  

doi:10.4038/jnsfsr.v36i1.133

Journal of the National Science Foundation of Sri Lanka 36 (1) 51-58