BAYER, RANDALL J.*, EDWARD W. CROSS, and NEIL H. BAGNALL. CSIRO, Division of Plant Industry, Australian National Herbarium, Canberra, ACT, 2601, Australia. - A reassessment of tribal affinities of several enigmatic genera of Australian Asteraceae, based on three chloroplast sequences.
Several genera of Australian sunflowers have been doubtfully placed in
various tribes throughout their taxonomic history. Our continuing
studies of relationships within the Gnaphalieae have led us to
investigate the tribal placement of these enigmatic genera. Therefore,
the objective of this study was to elucidate tribal relationships of
Cratystylis S. Moore, Isoetopsis Turcz., and
Centipeda Lour. by reconstructing their phylogeny within the
subfamily Asteroideae This has been accomplished through the use of
sequence data from the trnL intron, trnL/trnF intergenic
spacer and matK coding region. Cratystylis is a genus of
four endemic Australian arid zone shrubs. It has been variously
included in the Astereae, Inuleae s. ampl., and even in
a paraphyletic Cichorioideae. The monotypic Australian genus
Isoetopsis has been assigned to the Anthemideae, quite often as
a section within the genus Cotula, as Cotula sect.
Isoetopsis (Turcz.) Baillon. A placement of Isoetopsis
within the Astereae and Gnaphalieae has also been suggested.
Centipeda is a genus of five species inhabiting Australia,
South America, and New Zealand. Although traditionally a member of the
informal group 'Cotuleae' in the Anthemideae, recent workers have
considered it to be in Astereae or Gnaphalieae. Detailed morphological
studies support neither of these placements and hence it is currently
unassigned. Molecular data does not support the inclusion of the three
genera in Gnaphalieae, instead there is general agreement between the
tribal placement of these genera based on our molecular analysis and
certain morphological and secondary chemical characters.
Key words: Asteraceae, Centipeda, Cratystylis, Gnaphalieae, Isoetopsis, phylogeny