HUANG, MINGJUAN*, JOHN V. FREUDENSTEIN, AND DANIEL J. CRAWFORD. Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210. - Phylogenetic relationships of the Caryopteris-Trichostema complex (Lamiaceae) based on ndhF sequence data.
The so-called Caryopteris-Trichostema complex consists of these
two genera and several monotypic or very small genera.
Trichostema is North American where all other taxa are Asiatic.
The complex has been problematic taxonomically, and Cantino in
particular, has questioned the monophyly of Caryopteris. A
molecular phylogenetic study of the complex was carried out using
sequences from the chloroplast ndhF gene. The monophyly of
Trichostema is strongly supported in the molecular phylogeny
and three major clades are present in the genus. The lineages
correspond closely to groupings recognized by Harlan Lewis, with the
notable exception of T. brachiatum. Implications of the
placement of this species in the molecular phylogeny will be discussed
relative to the evolution of annuality and base chromosome number.
The ndhF phylogeny suggests that Caryopteris is
polyphyletic. Section Caryopteris is strongly supported as
monophyletic and is sister to Trichostema. The monotypic genus
Amethystea is nested within the complex and is closely related
to the above group of Trichostema and Caryopteris s.s..
Section Pseudocaryopteris (C. bicolor and C.
paniculata) appears to be a natural group, thus supporting its
elevation from the sectional to generic level as proposed by Cantino
et al. (1998). Caryopteris divaricata, characterized by its
porate pollen and delimited as the monotypic genus Tripora by
Cantino, is sister to Pseudocaryopteris in a moderately
supported clade. Caryopteris nepetifolia and C.
terniflora form a strongly supported group together with
Schnabelia, providing additional evidence to support the
transfer of the former two species of Caryopteris to the genus
Schnabelia. Rubiteucris is well supported as sister to
Schnabelia rather than to the rest of Caryopteris.
These results are largely congruent with relationships inferred from
ITS sequence data, but provide better resolution.
Key words: Caryopteris, Lamiaceae, ndhF, phylogeny, Trichostema