Tyrrell, Christopher D. , Triplett, Jimmy K. , Santos-Gonçalves, Ana Paula , Londono, Ximena , Clark, Lynn G. .
Phylogeny, morphological evolution, and generic classification within Arthrostylidiinae (Poaceae: Bambusoideae: Bambuseae).
Arthrostylidiinae is a neotropical woody bamboo subtribe comprising 13 genera and about 165 described species. Molecular evidence supports a Guaduinae + Arthrostylidiinae clade, but Arthrostylidiinae is recovered as sister to or paraphyletic to a robustly monophyletic Guaduinae, whereas morphology supports the monophyly of each subtribe. Despite the morphological cohesion of the Arthrostylidiinae, the characters used to delimit its genera often intergrade, making taxonomy of the group difficult. Prior molecular analyses lacked breadth of sampling, thus the internal relationships among the genera are uncertain. Our objectives are to: 1) test the monophyly of Arthrostylidiinae and its genera, 2) resolve some of the phylogenetic relationships among Arthrostylidiinae lineages, and 3) examine evolution of morphological characters using our phylogenetic hypothesis. We generated maximum parsimony (MP) and Bayesian phylogenies of 35 taxa (29 representing 11 of the 13 Arthrostylidiinae genera, 5 representing each Guaduinae genus, and an outgroup taxon) using sequence data from both coding (ndhF) and non-coding (trnD-trnT, trnC-rpoB, rps16-trnQ, rpl16 intron) chloroplast DNA regions. Our results support the monophyly of the subtribe and recover 5 subclades. Within our sampling scheme, several genera appear polyphyletic, including Arthrostylidium, Rhipidocladum, and Aulonemia. Furthermore, Rhipidocladum section Didymogonyx forms a polytomy with Elytrostachys and Arthrostylidium (in part) + R. section Rhipidocladum + R. section Racemiflorum. The two species of R. section Didymogonyx share a suite of characters unique within the subtribe. Consequently--and in light of this new molecular evidence--we elevate R. section Didymogonyx to generic status, and distinguish it based on gross morphology and foliar micromorphology. Finally, our phylogenetic hypothesis suggests multiple origins of apsidate (fan-like) branching, a character shared by Actinocladum, Merostachys, and all sections of Rhipidocladum (including the new genus Didymogonyx).
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1 - Iowa State University, Department of Ecology, Evolution, and Organismal Biology, 253 Bessey Hall, Ames, Iowa, 50011-1020, USA
2 - University of Missouri-St. Louis, Department of Biology, One University Boulevard, St. Louis, Missouri, 63121, USA
3 - Universidade Estadual do Centro-Oeste do Paraná, Depto. de Ciências Biológicas, Campus CEDETEG, R. Simeão Camargo Varela de Sá, 03, Cascavel, Guarapuava, Paraná, 85040-080, Brazil
4 - Instituto Vallecaucano de Investigaciones Científicas-INCIVA, Apartado Aéreo 5660, Cali, Colombia
5 - Iowa State University, Department of Ecology, Evolution & Organismal Biology, 253 Bessey Hall, Ames, Iowa, 50011-1020, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 3:15 PM