Sarcostemma R.Br. (Apocynaceae ? Asclepiadoideae) ? a controversial generic circumscription reconsidered: Evidence fromtrnL-F spacers

Monophyly and sister group relationship of Ceropegieae and Marsdenieae, the two Asclepiadoideae tribes possessing erect pollinia, are confirmed by molecular investigation of noncoding cpDNA markers (trnTL and trnLF spacers, and the trnL intron). In Ceropegieae, the analyzed taxa fall in four subclades. The Heterostemma subclade is sister to other three subclades, of which the ConomitraLeptadeniaOrthanthera subclade is sister to the AnisotomaNeoschumanniaRiocreuxiaSisyranthus subclade and to the large subclade comprising the stemsucculent stapeliads, Brachystelma and Ceropegia. Following these results, subdivision of Ceropegieae into four subtribes, Anisotominae, Heterostemminae, Leptadeniinae and Stapeliinae, is proposed.

Section: Discussionmentioning

confidence: 52%

Subtribal division of Ceropegieae (ApocynaceaeAsclepiadoideae)

Meve

Liede

2004

“…In each case the position of G. sylvestre is supported by a high bootstrap percentage, indicating that its combined trnL-F may represent a hybrid sequence. Although trnL-F intergenic spacer represents less than 25% of the total sequence of these three regions (trnT-L intergenic spacer, trnL intron and trnL-F intergenic spacer), the use of this sequence of G. sylvestre as an outgroup may disturb analyses and might, for instance, explain the basal polytomy in Liede & Täuber (2000).…”

Section: Methodsmentioning

confidence: 99%

Asclepiadeae classification: evaluating the phylogenetic relationships of New World Asclepiadoideae (Apocynaceae)

Rapini

Chase

Goyder

et al. 2003

To provide an overview of New World Asclepiadoideae, we here evaluate Asclepiadeae classification by comparing the taxonomic arrangement of subtribes with a topology obtained through analyses of two plastid DNA regions (trnL intron and trnLF intergenic spacer) for 111 species of Asclepiadoideae representing the major lineages of the subfamily. Without Jobinia, Nephradenia and Barjonia, Asclepiadeae are not monophyletic. The monotypic African genus Eustegia, with pendent pollinia, may represent the sister clade of Marsdenieae Ceropegieae, the group composed of plants with erect pollinia. Metastelmatinae including African plants are also nonmonophyletic, and the circumscription of the recently reinstated Cynanchinae should be studied further. Overall, Asclepiadeae are composed of three main clades. The Old World Astephaninae are the sister group of the other Asclepiadeae, which are divided into the ACTG (Asclepiadinae, Cynanchinae, Tylophorinae and Glossonematinae) and MOG (Metastelmatinae, Oxypetalinae and Gonolobinae) clades. According to this study, the New World Asclepiadoideae fall into just four clades: (1) Marsdenia (Marsdenieae), (2) Asclepias (Asclepiadinae, Asclepiadeae), (3) Cynanchum subgenus Mellichampia (Cynanchinae, Asclepiadeae), and (4) MOG, the clade comprising the majority of New World Asclepiadoideae.

“…The genus was usually considered close to Philibertia, and Holm (1950) treated the two genera in Sarcostemma s.l. Evidence from the trnT-F region (Liede & Täuber, 2000) placed Philibertia closer to Blepharodon than to Funastrum. However, a greater sampling of trnL-F (Rapini & al., 2003) placed Philibertia within Oxypetalinae, closer to Funastrum than to Blepharodon, which has been confirmed in analyses with more plastid regions (Liede-Schumann & al., 2005, and this study).…”

Section: Discussionmentioning

confidence: 97%

Phylogenetics of South American Asclepiadoideae (Apocynaceae)

Rapini

Chase

Konno

2006

According to analyses of plastid DNA, New World Asclepiadoideae (Apocynaceae) fall into four clades; most species, however, are included in just one clade endemic to the New World that comprises Metastelmatinae, Oxypetalinae and Gonolobinae (the MOG clade). Looking for better support and resolution inside the MOG core group, we sequenced the nuclear ribosomal DNA region ITS and increased the number of plastid regions (trnS‐G and matK) sequenced. Because of high levels of intra‐individual polymorphisms and complex alignment among subtribes, ITS could not be used at the subtribal level. According to combined analysis of the plastid regions, Blepharodon lineare and Funastrum clausum are confirmed as sister group to the rest of Metastelmatinae and Oxypetalinae, respectively. The analysis indicates that Ditassa is polyphyletic. A highly supported clade composed of shrubby species with minute leaves that were traditionally classified in Ditassa comes out as sister to the rest of the subtribe apart from B. lineare. These data clearly support the recognition of a new genus in Metastelmatinae.