Abstract:
Species diversity and classification of thraustochytrids isolated from fallen senescent leaves of mangrove trees collected from Ban Pred Nai, Trad Provice were investigated. The total of 416 isolates of thraustochytrids were obtained. The percentage of occurrence retrieved from leaves of Rhizophora apiculata,Brugueira gymnorrhiza, Sonneratia ovata, Avicennia alba, Lumnitzera racemosa, Acrostichum aureum, and Hibicus tiliaceus was 100 %, while the presence of thraustochytrids on Ceriops tagal, Heritiera littoralis, Phoenix paludosa, and Xylocarpus granatum leaves were accounted as 99.33%,90%,86.67% and 73.33%, respectively. These thraustochytrids comprised of at least two genera, Schizochytruim and Ulkenia. According to this study, six species of Schizochytruim were found and Schizochytruim mangrovei was the predominant species (42.86% of total mangrove leaves). Other five species of Schizochytruim isolated simultaneousty were consisted of Schizochytruim limacinum (38.57%), Schizochytruim sp.1 (26.43%), Schizochytruim sp.2 (6.43%), Schizochytruim sp.6 (0.71%), and Schizochytruim sp.8 (5.71%). In addtion, three species of Ulkenia were found and described as Ulkenia sp.1 (22.86%),Ulkenia sp.2 (13.57%), and Ulkenia sp.3 (4.29%). However,there was one unknow species which was accounted for 7.24 %. Apart from these, Labyrinthula sp. was the only one species found in this area (4.29%) which belonged to the Family Labyrinthulaceae. The results suggested that the distribution of the thraustochytrids species isolated from this mangrove site was dependent on the species of mangrove trees.