Simaroubaceae,an artificial construct: evidence from rbcL sequence variation

Phylogenetic analyses of rbcL sequence data of representatives of all subfamilies indicate that Simaroubaceae sensu lato is polyphyletic. It represents at least five separate lineages, only three of which (Simarouboideae, Harrisonia, and Kirkioideae) cluster within a robust sapindalean clade. The family is monophyletic only when comprised of members of the subfamily Simarouboideae plus Leitneriaceae, but excluding Harrisonia. Harrisonia is most closely related to Cneorum and Rutaceae. Kirkioideae is distant from Simaroubaceae sensu stricto, although its affinities remain within Sapindales. The other two lineages show an affinity to taxa at some distance from Sapindales: lrvingia with a group of poorly sampled rosid I taxa comprising in part members of Linales and Malphigiales; Picramnia and Alvaradoa cluster together in an isolated position between the broadly comprised groups of rosid I and rosid II. Support for the affinities suggested here is also evident in nonmolecular data sources: wood anatomy, pericarp structure, pollen, and phytochemistry. The elevation of the picramnioid clade, comprising Picramnia and Alvaradoa, to family rank is signaled, and the recognition of Kirkiaceae and Irvingiaceae is substantiated.