| Summary: | There are a total of 35 taxa of Dipterocarpus comprising of 27 species and 8 subspecies occurring
in Sarawak. The species included were Dipterocarpus acutangulus Vesque, D. applanatus
Slooten, D. borneensis Slooten, D. caudiferus Merr., D. confertus Slooten, D. coriaceous Slooten,
D. costulatus Slooten, D. crinitus Dyer, D.cuspidatus P.S. Ashton, D.elongatus Korth., D.
eurynchus Miq., D. fagineus Vesque, D. glabrigemmatus P.S. Ashton, D. globosus Vesque, D.
gracilis Blume, D. humeratus Slooten, D. kunsteri King, D. lowii Hook f., D. mundus Slooten, D.
nudus Vesque, D. oblongifolius Blume, D. pachyphyllus Meijer, D. rigidus Ridl., D. sarawakensis
F.G. Brown ex Slooten, D. sublamellatus Fowx., D. tempehes Slooten and D. verrucosus Foxw.
ex Slooten. The eight subspecies included were D. caudatus ssp. peniangianus Fowx., D. conformis
Slooten ssp. borneensis P.S Ashton, D. geniculatus Vesque ssp. geniculatus Vesque, D.
geniculatus Vesque ssp. grandis P.S Ashton, D. palembanicus Slooten ssp. borneensis P.S Ashton,
D. palembanicus Slooten ssp. palembanicus Slooten, D. stellatus Vesque ssp. stellatus, and D.
stellatus Vesque ssp. parvus P.S. Ashton. The first aspect of this study includes morphological
observations based on herbarium specimens deposited at Sarawak Herbarium (SAR), Herbarium
UNIMAS (HUMS), and specimens collected from the field. The second aspect include anatomical
studies focused on the leaf microstructures, particularly the stomata types and epidermal cell
features of the selected Dipterocarpus spp. This aspect of studies involved leaf clearing method
for light microscopy observations and investigation of the microstructures using the Scanning
Electron Microscope (SEM). The third aspect involved examination of pollen microstructures of
the selected Dipterocarpus spp. under the SEM. Morphological characteristics of 35 taxa of
Dipterocarpus were described and documented as an updated of the previous study by Ashton, 2004. Based on the herbarium specimens and field observation made, description of the species
and key for the species identification are included. The main morphological characteristics that
distinguished the species and subspecies within the genus Dipterocarpus are the leaf and the fruit
characteristics. The microstructures of the leaves based on the seven species investigated, depicts
that the stomata types are also considered additional new information and are good characteristics
for species and subspecies identification. All the species investigated have hypostomatic leaf,
anomocytic, anomo-cyclocytic, and paracytic stomata types. The pollen of the nine species
investigated were of spheroidal-shaped, with reticulate exine and diameter size ranges 48.0 – 63.0
μm. The conservation status of the Dipterocarpus spp. are included based on the Sarawak Plant
Red List, Plant Red List Peninsular Malaysia, and IUCN Red List (2013). Of all the species,
Dipterocarpus oblongifolius is one of the two totally protected plant species in Sarawak under the
Sarawak Wildlife Ordinance 1998. This species has been listed as totally protected plant species
due to its ecological importance and key stone species for the terrestrial and aquatic wildlife. There
are three Dipterocarpus spp. recorded as endangered and 13 as critically endangered based on the
IUCN Red List 2013. The ecological notes, distribution and the conservation status from the three
lists will be very important for future conservation management especially to the endangered and
critically endangered species as to avoid local extinction.
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