In the last decade, efforts to reconstruct suprageneric phylogeny of the Cyperaceae have intensified. We present an analysis of 262 taxa representing 93 genera in 15 tribes, sequenced for the plastid rbcL and trnL-F (intron and intergenic spacer). Cyperaceae are monophyletic and resolved into two clades, here recognised as Mapanioideae and Cyperoideae, and the overall topology is similar to results from previous studies. Within Cyperoideae, Trilepideae are sister to rest of taxa whereas Cryptangieae, Bisboeckelerieae and Sclerieae are resolved within Schoeneae. Cladium and Rhynchospora (and Pleurostachys) are resolved into clades sister to the rest of Schoeneae, lending support to the recognition of these taxa in separate tribes. However, we retain these taxa in Schoeneae pending broader sampling of the group. The phylogenetic position of 40 species in 21 genera is presented in this study for the first time, elucidating their position in Abildgaardieae (Trachystylis), Cryptangieae (Didymiandrum, Exochogyne), Cypereae (Androtrichum, Volkiella), Eleocharideae (Chillania), and Schoeneae (Calyptrocarya, Morelotia). More sampling effort (more taxa and the use of more rapidly evolving markers) is needed to resolve relationships in Fuireneae and Schoeneae.
No abstract
Since the Monocots II meeting in 1998, significant new data have been published that enhance our systematic knowledge of Cyperaceae. Phylogenetic studies in the family have also progressed steadily. For this study, a parsimony analysis was carried out using all rbcL sequences currently available for Cyperaceae, including data for two new genera. One of the four subfamilies (Caricoideae) and seven of the 14 tribes (Bisboeckelereae, Cariceae, Cryptangieae, Dulichieae, Eleocharideae, Sclerieae, Trilepideae) are monophyletic. Subfamily Mapanioideae and tribe Chrysitricheae are monophyletic if, as the evidence suggests, Hellmuthia is considered a member of Cypereae. Some other features of our analysis include: well-supported Trilepideae and Sclerieae-Bisboeckelereae clades; a possible close relationship between Cryptangieae and Schoeneae; polyphyletic tribes Schoeneae and Scirpeae; the occurrence of Cariceae within the Dulichieae-Scirpeae clade, and a strongly supported clade, representing Cyperus and allied genera in Cypereae, sister to a poorly supported Ficinia-HellmuthiaIsolepis-Scirpoides clade. Such patterns are consistent with other studies based on DNA sequence data. One outcome may be that only two subfamilies, Mapanioideae and Cyperoideae, are recognized. Much further work is needed, with efforts carefully coordinated among researchers. The work should focus on obtaining morphological and molecular data for all genera in the family.
Using a DNA-based tree as the framework, the homology of key taxonomic characters in tribe Cypereae (900 species in 19 genera, the largest of which is Cyperus) is assessed and revisit the question of generic circumscription. Plastid DNA (rbcL gene, rps16 intron, trnL intron and trnL-F intergenic spacer) sequence matrix for 50 species in 19 genera of Cypereae is analysed using the maximum parsimony algorithm of PAUP. Two major groups are observed: the Ficinia and Cyperus clades. The Ficinia clade includes taxa with a center of diversity in the Cape Floristic Region of South Africa. These are predominantly perennial herbs (with exception of Isolepis, which is predominantly annual) having non-Kranz (C 3 ) anatomy and spirally arranged glumes. Species of the Cyperus clade have a predominatly distichous glume arrangement and Kranz anatomy which is either absent (C 3 ) or present (C 4 ). Cyperus is the core genus in the Cyperus clade, in which 13 additional segregate genera are embedded. These segregate genera differ from typical Cyperus in one or more of a few gross morphological characters. There are no unambiguous characters separating C 3 and C 4 Cyperus species. The circumscription of Cypereae is broadened to include all taxa with a Cyperus-type embryo and perianth segments. Three taxa possessing perianth segments, namely Hellmuthia membranacea, Scirpus falsus and S. ficinioides, are supported to be closer to Cyperus than to Scirpus.
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