OCHOTERENA, HELGA. L. H. Bailey Hortorium, 462 Mann Library, Cornell University, Ithaca, NY, 14853. - Phylogeny and character evolution in Hintonia (Rubiaceae) and related taxa.
The systematic position of the genus Hintonia Bullock within
Rubiaceae has been controversial. Cladistic analyses of the
chloroplast ribulose biphosphate carboxylase-oxygenase large subunit
(rbcL) DNA sequences including a wide range of taxa from within
and outside Rubiaceae have been conducted. These studies suggest that
Hintonia is related to genera belonging to the
Portlandia group forming a monophyletic clade that also
includes members of the Chiococceae and Catesbaeae tribes in addition
to Exostema (Pers.) Humb. & Bompl. Previous classifications do
not entirely reflect the relationships suggested by the rbcL
analyses. A combined analysis including rbcL and morphology
provides the basis for the interpretation of the evolution of
characters traditionally used in the taxonomy of the family. These
characters include life form, presence/absence of raphides, flower
arrangement, flower aestivation, unit of pollen dispersal, texture of
the fruit, pattern of fruit dehiscence, and presence/absence of a wing
on the seed. A morphological cladistic analysis with a greater
sampling of the taxa likely to be related to Hintonia provides
further evidence for the interpretation of the phylogenetic
relationships of these genera and the evolution of additional
characters. These characters include: pattern of wax deposition in
the leaves, point of insertion of the stamens in the corolla, pollen
aperture number and type, placentation and placenta characters, seed
orientation and seed coat characters. The morphological studies
suggest that only three species endemic to Mexico and Guatemala should
be recognized within Hintonia.
Key words: character evolution, combined analysis, Hintonia, Portlandia group, rbcL, Rubiaceae