REVISED CIRCUMSCRIPTIONS AND SUBGENERIC TAXONOMIES OF CALANDRINIA AND MONTIOPSIS (PORTULACACEAE) WITH NOTES ON PHYLOGENY OF THE PORTULACACEOUS ALLIANCE

Cladistic analysis of Portulacaceae supports a revised taxonomy of Calandrinia sensu lato. Calandrinia, as here circumscribed, comprises ca. 14 western American species in three sections: Calandrinia, Acaules, and Monocosmia. Previous taxonomies classified over 100 species in Calandrinia but recognized Monocosmia as a distinct genus. Calandrinia sects. Calandrinia and Monocosmia are probably cladistically nested in section Acaules and are not sister groups of either Rumicastrum or Montia, as proposed in a previous cladistic analysis. Montiopsis Kuntze, traditionally included in Calandrinia, comprises ca. 15 western South American species in two subgenera, Montiopsis and Dianthoideae. At present, cladistic analysis provides only weak evidence linking Calandrinia and Montiopsis to one another and poorly resolves their precise relationships to other Portulacaceae. This analysis supports a taxonomic distinction between the eastern American/African and western American members of Portulacaceae, but poorly resolves the relationship between the two groups. Cactaceae, Basellaceae, Didiereaceae, and perhaps Hectorellaceae, which were not included in the analysis, belong to the eastern American/African group. The present analysis provides a framework for additional studies of phylogeny of the portulacaceous alliance and of Centrospermae in general.