SOSA, VICTORIA1* and MARK, W. CHASE2. 1Instituto de Ecologia, A. C., Apdo. Postal 63, 91000 Xalapa, Veracruz, Mexico; 2Molecular Systematics Section, Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, U.K. - Phylogeny of the Crossosomataceae based on rbcL sequence data.
Crossosomataceae are a group of shrubs from North America and Mexico,
that includes four genera: Crossosoma , Apacheria ,
Forsellesia and Velascoa . Apacheria and
Velascoa are monotypic. Relationships of the genera and
monophyly of the family have not yet been tested. We evaluated these
issues using rbcL chloroplast DNA sequence data. By analyzing the
sequences of representatives of the four genera with that of the
"Eudicots" we concluded that they constitute a monophyletic
group and that their phylogenetic position corresponds with previous
angiosperm phylogenies. A more restricted analysis with the most
closely related taxa showed that Apacheria and Velascoa
are closely related. They share morphological characters such as
form and position of petals and fimbriate aril. Phytogeographical
patterns are discussed. Velascoa is the only genus that
reaches central Mexico pine-oak forests and it is not found in
northern xerophytic habitats like the rest of the Crossosomataceae.
Key words: Crossosomataceae, molecular systematics, rbcL sequences