Phylogeny, Distribution, and Classification of the Coreopsideae (Asteraceae)

Abstract

The phylogeny of the tribe Coreopsideae was investigated by cladistic analysis of generic interrelationships using a set of 37 morphological characters. The cladograms display three main groups: 1) a rather vaguely characterized assemblage of mainly American genera, viz. Co- reopsis, Cosmos, Heterosperma, Henricksonia, Dahlia, Thelesperma, Coreocarpus, Cyathomone, Ericentrodea, and Narvalina, 2) a strongly supported monophyletic group consisting of Glossocardia, Isostigma, Guerreroia, Glossogyne, Chrysanthellum, Eryngiophyllum, and Neuractis, and 3) another presumably monophyletic, albeit less well supported group of Hidalgoa, Moonia, Petrobium, Oparanthus, and Fitchia. The position of Bidens is uncertain, either within the first group or as sister group to the third. The three groups are formally recognized as the subtribes Coreopsidinae, Chrysanthellinae subtribe nov., and Petrobiinae. The Chrysanthellinae and the Petrobiinae exhibit mainly Pacific distribution patterns, although Petrobium occurs on St. Helena. Oparanthus and Fitchia, both from Polynesia, are sister genera. Fitchia is well nested within the Coreopsideae, and the analysis strongly supports its inclusion in the tribe.