A Preliminary Molecular Phylogeny of the Rhynchosporeae (Cyperaceae)

Abstract

The tribe Rhynchosporeae comprises the genera Rhynchospora and Pleurostachys and has never been studied using molecular techniques. The objective of this study was to use an analysis of trnL-F sequences to evaluate the hypothesized taxonomic divisions within the Rhynchosporeae including the monophyly of the genera and the soundness of the subgenera and sections. A total of 44 ingroup species were studied, 41 of Rhynchospora representing 22 of Kükenthal's 28 sections, and three of Pleurostachys. Five outgroup species from other genera were also included. The cladistic analysis of 50 trnL intron and trnL-F intergenic spacer sequences resulted in 16 trees and a strict consensus tree. The Rhynchosporeae form two well-supported primary clades with several well-supported smaller clades, many of which agree with previously hypothesized sections. Pleurostachys is embedded within the second primary clade.

Pleurostachys (Cyperaceae): nomenclatural notes, geographical distribution and conservation status

“…Pleurostachys is here also confirmed as a genus endemic to the tropical and subtropical areas of South America (Goetghebeur 1998;Govaerts et al 2007;Thomas et al 2009). It is often found in the understory of humid and shady forests and close to streams.…”

“…In more recent studies both genera emerge mixed up (Goetghebeur, 1998;Thomas et al 2009) and the phylogenies show no support for them being separate genera (Thomas & Alves 2008;Thomas et al 2009) neither for Pleurostachys nor Rhynchospora.…”

Evolution and Development of the Spikelet and Flower ofRhynchospora(Cyperaceae)

“…Subfamily Cyperoideae has ∼90 genera, the largest being Carex (more than 1828 species) and Cyperus (more than 702 species; Govaerts et al 2013); Rhynchospora Vahl, with ∼354 species, is the third-largest genus in subfamily Cyperoideae and is mainly distributed in the American savannas (Koyama 1972;Strong 2006;Thomas et al 2009). The current classification of the genus follows Kü kenthal (1949,1950,1951,1952).…”

“…Other characters commonly used to circumscribe the species of Rhynchospora were the inflorescence type, the presence/absence of perianth, and the shape and size of the fruit (Kü kenthal 1949(Kü kenthal , 1950(Kü kenthal , 1951(Kü kenthal , 1952Koyama 1972;Thomas 1992;Strong 2006). Recently, in a preliminary analysis of the Rhynchosporeae based on molecular data (trnL intron and trnL-F intergenic spacers), Kü kenthal's infrageneric division based on the morphology of the style was not supported by the phylogeny (Thomas et al 2009). According to these results, Rhynchospora may be paraphyletic relative to the genus Pleurostachys (member of the Rhynchosporeae tribe), and the subgenus Haplostyleae (Kü kenthal 1949(Kü kenthal , 1950(Kü kenthal , 1951(Kü kenthal , 1952 appears to be divided into several smaller clades instead of being a natural group.…”

Morphological and genomic characterization of Rhynchospora tenuis complex (Cyperaceae) and its taxonomic implications

“…We have included R. breviuscula to this comparison because it belongs to R. sect. Dichromena, which was considered by Thomas et al (2009) as a very close group of R. sect. Tenues.…”