Phylogenetic and systematic studies of the schismatoglottideae (araceae: aroideae)
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Date
2009
Authors
Wong, Sin Yeng
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Abstract
The tribe Schismatoglottideae is the most diverse aroid taxon in Borneo, comprising in
excess of 100 species of which over 95% are endemic. Besides Schismatoglottis Zoll. &
Moritzi, the largest genus within the tribe, the tribe includes four small satellite genera,
Aridarum Ridl., Bucephalandra Schott, Phymatarum M. Hotta dan Piptospatha N.E. Br.
that are endemic to Borneo, except the last which extends to the Malay Peninsular and
Southern Peninsular Thailand. Recent and ongoing research of the Schismatoglottideae
includes alpha-taxonomy, phenological and ecological studies have provided a stable
species platform from which to describe the considerable novelties still known to exist,
and from which to test hypotheses of infra-tribal, and intergeneric phylogenetic
processes. In addition, considerable research remains to be done to resolve generic
boundaries within the tribe. This study was carried out to: (1) undertake extensive field
studies including vouchering of sampled populations belonging to tribe
Schismatoglottideae; (2) resolve by use of molecular methodologies the internal
phylogeny of the tribe using molecular methodologies; (3) investigate, by field and
laboratory observations on inflorescence morphology, pollination, dispersal and seedling
establishment processes, and by mapping relevant features onto phylogenetic trees to
produce an hypothesis of the evolution of these adaptations. A combined molecular
phylogenetic analysis of matK, the 3' portion of the trnK intron, and trnL-F DNA
sequence data was carried out on 78 taxa representing all genera in the tribe, all informal
groups in Schismatoglottis, together with sister tribe Cryptocoryneae, and outgroups
from Araceae. Analyses of combined DNA datasets with parsimony, maximum
likelihood, and Bayesian methods revealed tribe Schismatoglottideae to be a
polyphyletic assemblege. Neotropical Schismatoglottis is shown to be sister to the
palaeotropical Schismatoglottideae + Crytocoryneae. Schismatoglottis acuminatissima is
a sister clade to the rest of the Schismatoglottideae. Palaeotropical Schismatoglottis is
unsupported as a monophyletic genus. A new neotropical tribe of Araceae: Aroideae,
Philonotieae S.Y. Wong & P.C. Boyce, is proposed. Philonotieae is sister to
Crytocoryneae + palaeotropical Schismatoglottideae, with these three tribes comprising
the schismatoglottid alliance. Apoballis, Hestia, Pichinia and Schottarum are removed
from Schismatoglottis sensu stricto into separate genera. Bakoa and Ooia are removed
from Piptospatha, proposed as new genera. The morphological characters that facilitate
rheophytism are: (1) Ability for shoot/root disarticulation; (2) Free ligular sheath soon
becoming marcescent; (3) Presence of micropylar appendage and, (4) Presence of splash
cup.
Description
PhD
Keywords
Biological Science , Phylogenetic , Schismatoglottideae