Taxonomic Considerations on Metastelmatinae (Apocynaceae) Based on Plastid and Nuclear DNA

Abstract

The Metastelmatinae (Asclepiadoideae, Apocynaceae) include 13 genera and approximately 260 species with complex morphological affinities that are broadly distributed in the Neotropics. This study investigated phylogenetic relationships within this subtribe using plastid {trnT-F, trnS-G, trnH-psbA, trnD-T, rpsl6, and matK) and nuclear (ITS) markers. The taxonomic sampling focused on the South American species, and included approximately 25% of the subtribe. Individual data partitions, and combined datasets were analyzed using Bayesian inference, maximum likelihood, and maximum parsimony. The results indicated that most genera of Metastelmatinae are not monophyletic. Internal relationships in the subtribe and key morphological characters used in the taxonomy of the group are discussed. The lack of resolution in the molecular phylogeny, incongruent phylogenetic signals between plastid and nuclear datasets, and the lack of morphological features for individual clades prevented major taxonomic changes in this group, those of which were restricted to the inclusion of Barjonia harleyi and Hemipogon harleyi into Minaria forming the new combinations Minaria harleyi and M. volubilis, and the synonymy of Macroditassa under Peplonia with the new combinations Peplonia adnata and P. macrophylla.

Systematics ofPrestonia(Apocynaceae: Apocynoids: Echiteae) 80 Years After Woodson

“…Clades from the consensus tree are based on the combined molecular dataset (combined cpDNA and nrDNA datasets) ( the design and identification of universal primers are somewhat difficult due to the polyploidy present in plants (Naumann et al, 2011). Here, the nrDNA data are congruent with those based on cpDNA data; however, incongruence between nuclear and plastid data is not uncommon (e.g., Fan et al, 2009;Pelser et al, 2010;Silva et al, 2012).…”

“…Endress and Bruyns (2000) recognized five subfamilies: Rauvolfioideae and Apocynoideae from the traditional Apocynaceae, and Periplocoideae, Secamonoideae, and Asclepiadoideae from the traditional Asclepiadaceae. Since then a number of phylogenetic studies have contributed to the resolution of relationships at the tribal, subtribal, or generic level, which has led to the reorganization or description of tribes and subtribes and the synonymization of several genera (e.g., Meve & Liede, 2004;Simões et al, 2004Simões et al, , 2006Simões et al, , 2010Liede-Schumann et al, 2005;Rapini et al, 2006Rapini et al, , 2011Endress & Hansen, 2007;Endress et al, 2007aEndress et al, , 2007bLivshultz et al, 2007;Silva et al, 2012;Khanum et al, 2016;Meve et al, 2017;Morales et al, 2017). Despite these advances, many groups are still unresolved or the resolution is too low to accurately define their relationships.…”

Monsanima tinguaensis (Apocynaceae), an enigmatic new species from Atlantic rainforest

“…Morphological convergences are common in the subfamily and relationships are often difficult to derive based exclusively on morphology. Therefore, the use of phylogenetic analyses-especially based on molecular data (e.g., Liede & Täuber 2000, Rapini et al 2003, 2006, Liede-Schumann et al 2005, 2014, Silva et al 2012, Liede-Schumann & Meve 2013)-has profoundly changed the systematics of neotropical asclepiads.…”

“…For instance, the American genera Funastrum Fournier (1882: 388), Pentacyphus Schlechter (1906: 605) and Philibertia Kunth in Humboldt et al (1819: 195), once considered synonyms of Sarcostemma Brown (1810) (Holm 1950), were shown to belong to different subtribes: Funastrum and Philibertia to Oxypetalinae, and Pentacyphus to Pentacyphinae; while the palaeotropical Sarcostemma belongs to Cynanchinae (Liede & Täuber 2000, Endress et al 2014. Another example is the segregation of the genera of Malme´s (1927) Orthosieae: Peplonia Descaine (1844: 545), Gonioanthela Malme (1927: 6) and Macroditassa Malme (1927: 9)-three genera currently treated under Peplonia-were shown to belong to Metastelmatinae (Rapini et al 2004, Silva et al 2012, while the other two genera of the former 'Orthosieae', Orthosia Decaisne (1844: 526) and Jobinia Fournier (1885: 327), are closer to Scyphostelma Baillon (1890: 252), recently reinstated by Liede-Schumann & Meve (2013), and the recently proposed monotypic Monsanima Liede-Schumann & Meve (2013: 66) in Orthosiinae (Liede-Schumann et al 2005, Liede-Schumann & Meve 2013. Furthermore, most of the neotropical species of Cynanchum Linnaeus (1753: 212) were shown to belong to Orthosiinae rather than to Cynanchinae (Liede-Schumann et al 2005) and were recently transferred to Jobinia, Scyphostelma or Monsanima (Liede-Schumann & Meve 2013).…”

“…Silva in Silva et al (2012: 803) was originally described in Melinia Decaisne (1844: 588) (= Philibertia), a genus of Oxypetalinae, whereas Minaria T.U.P. Konno & Rapini in Konno et al (2006: 424), a genus segregated from Ditassa Brown (1810: 38), belongs to Metastelmatinae (Silva et al 2012). Diplolepis australis (Malme 1937: 2) Hechem & C.Ezcurra in Hechem et al (2011: 643) was originally described in Metastelma Brown (1810: 41), a genus of Metastelmatinae, and later transferred to Tweedia Hooker & Arnott (1834: 291), a genus of Oxypetalinae, whereas Diplolepis Brown (1810: 30) belongs to its own subtribe Diplolepinae (Endress et al 2014), not closely related to Metastelmatinae nor Oxypetalinae (Liede-Schumann et al 2005, Rapini et al 2007Hechem et al 2011).…”