Disintegrating Portulacaceae: a new familial classification of the suborder Portulacineae (Caryophyllales) based on molecular and morphological data

Abstract

Traditional classifications of the suborder Portulacineae recognize six families: Basellaceae, Cactaceae, Didiereaceae, Halophytaceae, Hectorellaceae, and Portulacaceae. However, phylogenetic analyses based on molecular sequence data indicate that the traditional family Portulacaceae is paraphyletic and consists of three distinct lineages that also include Cactaceae, Didiereaceae, and Hectorellaceae. We use sequence data from the chloroplast genes matK and ndhF representing 64 species of Portulacineae and outgroups to reconstruct their phylogenetic relationships with Bayesian and maximum parsimony inference methods. Evidence from these molecular phylogenetic analyses as well as from comparative morphological investigations allow us to propose a revised familial classification of the suborder Portulacineae. We recognize eight monophyletic families: Anacampserotaceae (Anacampseros, Grahamia, Talinopsis), Basellaceae, Cactaceae, Didiereaceae (incl. Calyptrotheca, Ceraria, Portulacaria), Halophytaceae, Montiaceae (incl. Hectorellaceae, Calandrinia, Cistanthe, Claytonia, Lewisia, Montia, Phemeranthus), Portulacaceae (Portulaca only), and Talinaceae (Amphipetalum, Talinella, Talinum). We provide a synopsis for this revised family classification with an identification key mainly based on habit and fruit characters, and family diagnoses with information on distribution, taxonomic diversity, and a brief discussion on phylogenetics and classification.