Systematics Section / ASPT
Lendel, Anita , Eggli, Urs , Nyffeler, Reto .
Phylogenetic relationships in the tribe Trichocereeae (Cactaceae) inferred from cpDNA sequence data analysis.
CACTI are remarkable for their large diversity of growth-forms, ranging from trees and shrubs to caespitose or single globular stems. The tribe Trichocereeae of subfamily Cactoideae comprises about 25 genera and some 250 to 300 distinct species, including some of the most diverse and attractive cacti from southern South America (i.e., Cleistocactus, Echinopsis, Rebutia). This tribe is particularly diverse in habit and related morphological characteristics. The phylogenetic relationships within the tribe Trichocereeae and its closest relatives from the tribes Browningieae and Cereeae are reconstructed based on chloroplast DNA sequences from the trnK intron (including the matK gene) and the rps16 intron. Overall, 38 taxa of Trichocereeae and 28 outgroup taxa of Cactoideae are used for parsimony and Bayesian analyses. The tribe Trichocereeae as traditionally circumscribed does not form a monophyletic group. Brachycereus and Jasminocereus, the two monotypic genera endemic to the Galapágos Islands form a well-supported clade sister to the Ecuadorian genus Armatocereus, and are nested in the HLP clade (name derived from initials of the tribes Hylocereeae, Leptocereeae and Pachycereeae). Discocactus, Espostoopsis, Facheiroa, Gymnocalycium, Lasiocereus, and Leocereus, are not part of core Trichocereeae, but show relationships with other representatives of the BCT clade (name derived from initials of the tribes Browningieae, Cereeae and Trichocereeae). Furthermore, there is no support for the monophyly of Rebutia, s.l. Within the BCT clade, a subclade of core Trichocereeae including genera such as Acanthocalycium, Cleistocactus, Echinopsis, Espostoa, and Weberbauerocereus, receives fairly good statistical support, though, they largely form a polytomy. An exception is a well supported clade comprising representatives of predominantly West-Andean genera characterized by producing flowers near the stem apices (i.e., Haageocereus, Mila, Matucana, Oreocereus, Oroya and Pygmaeocereus) whose relationships are clearly resolved. Aspects of growth-form evolution in core Trichocereeae will be discussed based on the available phylogeny.
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1 - Universität Zürich, Institut für Systematische Botanik, Zollikerstrasse 107, Zürich, CH-8008, Schweiz
2 - Sukkulenten-Sammlung Zürich, Mythenquai 88, Zürich, CH-8002, Schweiz
Presentation Type: Oral Paper:Papers for Sections
Date: Monday, July 31st, 2006
Time: 10:45 AM