Morphological and phylogenetic relationships of the genus Trichotosia blume (Orchidaceae) in Sabah

• Main Author: Norhaslinda Malekal
• Format: Thesis
• Language: English; English
• Published: 2012
• Subjects: QK495 Angiosperms
• Online Access: https://eprints.ums.edu.my/id/eprint/42411/1/ABSTRACT.pdf; https://eprints.ums.edu.my/id/eprint/42411/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/42411/

A study on the genus Trichotosia (Orchidaceae) in Sabah was carried out to determine useful morphological characters for its classification and to generate a phylogenetic relationship between its species in Sabah. Samples were collected from eight localities within Sabah, namely Mount Kinabalu, Mount Trus Madi, Mount Lumaku, Tawau Hills Park, Mount Tambuyukon, Mount Alab, Minduk Sirung, and Imbak Canyon Conservation Area. Morphological characteristics in the living plants were examined to determine informative characters for the genus classification. Subsequently, DNA was extracted from fresh leaves of Trichotosia using the cetyltrimethyl-ammonium bromide (CTAB) method. Molecular phylogenetic analysis using nuclear DNA sequence data from the internal transcribed spacer region (ITS1, ITS4) and the 5.8S gene for 20 taxa was conducted to examine the phylogenetic relationship of the genus. Descriptions of 16 flowering species based on morphological characteristics were presented. Out of these, one is a new record for Sabah, namely Trichotosia teysmannii (J.J. Sm.) Kraenzl., and Trichotosia poculata (Ridl.) Kraenzl. is new to Sabah and Borneo. An identification key for the 16 species of Trichotosia was presented. Hairs distribution, the positions of flower attachment to bract, inflorescences length and flower numbers are good morphological characters in identification. The strict consensus tree (Length=356; CI=0.8511; RI=0.800; RC=0.6809) obtained from parsimony analysis of the ITS sequence data showed that Trichotosia is divided into four groups (BS-98%). Two of the groups, however, were not fully resolved morphologically. The phylogenetic tree can be improved in the future by increasing the number of Trichotosia samples and using more markers, such as rbcl, trnL-F and matK. The ITS sequences provide supporting data for inferring relationships within Trichotosia that will be valuable for future classification.