Stenotus and Tonestus are small genera with
approximately six and nine species, respectively that occupy mid to
high elevation habitats in the western United States, Canada, and Baja
California. Sequence data obtained for the ITS region for several
samples of each species in these genera where incorporated into our
data base that contained representatives for most genera of North
American Astereae. After alignment, the matrix was subjected to
parsimony and Baysian analyses in order to assess phylogenetic
relationships among taxa. Based on ITS sequence data both genera, as
presently circumscribed, are polyphyletic. Stenotus was
resolved as three distinct lineages of two species each that were
sister to other Astereae. For example, the S. macleanii/S.
stenophyllus clade is sister to Tonestus lyallii. Another
clade with strong support consisted of T. alpinus,
Petradoria pumila, S. acaulis, and S.
armerioides. In general, the species of Stenotus are placed
near the Chrysothamnus/Solidago region in our phylogenetic
reconstruction. Two species of Tonestus, T. aberrans,
and T. kingii, where shown to be quite distant from their
present congeners and more closely related to the
Machaerantherinae-Eurybia-Symphyotrichum clade. ETS
sequence data are also being obtained to further test these hypotheses
of relationship. Morphological features that support the
sequence-based lineages are also being sought.
Key words: Asteraceae, Astereae, phylogeny, Stenotus, Tonestus