Showing papers in "Taxon in 2011"
TL;DR: The evidence for each of these postulated causes of diversification is reviewed, the need of more well-sampled and dated phylogenies is highlighted, and increased inter-disciplinary collaboration is urged.
Abstract: The Neotropical region (tropical America) is the most species rich region on Earth. Several causes have been proposed to explain this extraordinary biodiversity, which may be very roughly classified into two major categories: 'biotic' (e.g. soil adaptations; biotic interactions with pollinators, dispersers and herbivores; niche conservatism; dispersal ability) and 'abiotic' (e.g. time; rainfall, temperature and area; mountain uplift; hydrological changes). In this paper we review the evidence for each of these postulated causes of diversification and provide general directions towards further testing. We highlight the need of more well-sampled and dated phylogenies and urge increased inter-disciplinary collaboration.
437 citations
TL;DR: In Southern European regions, a lack of general phylogeographic patterns in these regions is one consequence as discussed by the authors, probably because patterns were simplified to a great extent by major losses of diversity during glacial periods.
Abstract: Interpretations of current diversity patterns based on the contraction/expansion model forced by climatic oscillations during the last two million years are commonplace in phylogeographic literature. Of the wealth of scientific studies accumulated during the past two decades in Europe, the ones we understand best are those mostly from higher latitudes, probably because patterns were simplified to a great extent by major losses of diversity during glacial periods. In Southern European regions (or in general, in those places where ice effects were less severe) the situation is quite different and to some extent opposite. These regions are referred to as refugia because they are known to contain more genetic diversity than elsewhere. This is not only due to preservation of genotypes that went extinct in other places, however, but also to the intensity and accumulation of a number of processes in a patchy landscape across a varied topography. A lack of general phylogeographic patterns in these regions is one consequence. Speaking of a single refugium to refer to each of the peninsulas, however, is an oversimplification. Even speaking of multiple unconnected refugia does not adequately reflect the complexity of the processes that shaped the current genetic and specific diversity.
231 citations
TL;DR: This work recircumscribe tribes and genera within Cucurbitaceae and present a more natural classification for this family, comprising 95 genera in 15 tribes, five of them new: Actinostemmateae, Indofevilleeae, Thladiantheae, Momordiceae, and Siraitieae.
Abstract: We analysed phylogenetic relationships in the order Cucurbitales using 14 DNA regions from the three plant genomes: the mitochondrial nad1 b/c intron and matR gene, the nuclear ribosomal 18S, ITS1-5.8S-ITS2, and 28S genes, and the plastid rbcL, matK, ndhF, atpB, trnL, trnL-trnF, rpl20-rps12, trnS-trnG and trnH-psbA genes, spacers, and introns. The dataset includes 664 ingroup species, representating all but two genera and over 25% of the ca. 2600 species in the order. Maximum likelihood analyses yielded mostly congruent topologies for the datasets from the three genomes. Relationships among the eight families of Cucurbitales were: (Apodanthaceae, Anisophylleaceae, (Cucurbitaceae, ((Coriariaceae, Corynocarpaceae), (Tetramelaceae, (Datiscaceae, Begoniaceae))))). Based on these molecular data and morphological data from the literature, we recircumscribe tribes and genera within Cucurbitaceae and present a more natural classification for this family. Our new system comprises 95 genera in 15 tribes, five of them new: Actinostemmateae, Indofevilleeae, Thladiantheae, Momordiceae, and Siraitieae. Formal naming requires 44 new combinations and two new names in Cucurbitaceae.
209 citations
TL;DR: The polyphyletic genus Chirita is remodelled after an extensive molecular phylogenetic study of species assigned to it and to other associated genera and a general list showing the present accommodation of the species previously described under ChiritA, Chiritopsis, Hemiboeopsis, Primulina and Wentsaiboea is provided.
Abstract: The polyphyletic genus Chirita is remodelled after an extensive molecular phylogenetic study of species assigned to it and to other associated genera. Most of Chirita sect. Chirita and the monotypic Hemiboeopsis are amalgamated with Henckelia sect. Henckelia , resulting in a very differently circumscribed genus Henckelia and the synonymisation of Chirita. The remaining species of Chirita sect. Chirita are accommodated in the revived genus Damrongia. Chirita sect. Liebigia is recognised as the genus Liebigia. Chirita sect. Microchirita is recognised as the genus Microchirita. Chirita sect. Gibbosaccus is, together with Chiritopsis and Wentsaiboea , included in the originally monotypic and now enormously expanded genus Primulina. The necessary combinations are made and a general list showing the present accommodation of the species previously described under Chirita , Chiritopsis , Hemiboeopsis , Primulina and Wentsaiboea is provided.
158 citations
TL;DR: The aim of the present study was to infer a substantially larger, more evenly sampled, phylogenetic tree for Caryophyllaceae in order to more confidently resolve relationships within this clade, and to propose the name Plurcaryphyllaceae for thisClade and provide a phylogenetic definition.
Abstract: The aim of the present study was to infer a substantially larger, more evenly sampled, phylogenetic tree for Caryophyllaceae in order to more confidently resolve relationships within this clade. This would allow us to evaluate previous classification schemes and to infer the evolution of a number of characters that have figured prominently in higher-level taxonomic treatments. We have inferred a 630-tip phylogeny (ca. 30% of the 2200 species) using maximum likelihood analyses of data from the nuclear ribosomal ITS region and five chloroplast genes and intergenic spacers: matK, ndhF, trnL-trnF, trnQ-rps16, and trnS-trnfM. Our results confirm that subfamily Paronychioideae is paraphyletic at the base of Caryophyllaceae. Alsinoideae and Caryophylloideae together form a clade, within which neither subfamily is monophyletic. With only a few exceptions, our results support the tribal classification presented by Harbaugh & al. (2010). In agreement with other recent studies, it appears that many of the larger genera are not strictly monophyletic. Our results imply that the first Caryophyllaceae had stipules, free sepals, small apetalous flowers with few stamens, and single-seeded indehiscent or irregularly dehiscing utricles. Stipules were lost along the branch to the Alsinoideae-Caryophylloideae clade, and the evolution of a tubular calyx marks Caryophylloideae. The evolution of petals, 10 stamens, and capsule fruits is inferred to have taken place along the branch subtending a clade that includes Sperguleae (mostly containing former members of Paronychioideae) and the remainder of Caryophyllaceae. As this previously unnamed major group is both well-supported in molecular phylogenetic studies and marked by clear-cut apomorphies, we propose the name Plurcaryophyllaceae for this clade and provide a phylogenetic definition.
150 citations
TL;DR: A taxonomic update of the Lamioideae subfamily is presented based on earlier published data as well as 71 new DNA extracts from relevant in- and outgroup taxa, and DNA sequence data from four chloroplast regions.
Abstract: Lamioideae comprise the second-largest subfamily in Lamiaceae. Although considerable progress has recently been made in Lamioideae phylogenetics, the subfamily remains one of the most poorly investigated subfamilies in Lamiaceae. Here we present a taxonomic update of the subfamily based on earlier published data as well as 71 new DNA extracts from relevant in- and outgroup taxa, and DNA sequence data from four chloroplast regions (matK, rps16, trnL intron and trnL-F spacer). The phylogenetic positions of 10 out of 13 previously unplaced small or monotypic Asian lamioid genera and 37 additional lamioid species have been identified, and the classification is updated accordingly. Results from parsimony and Bayesian phylogenetic methods corroborate earlier results, but phylogenetic resolution as well as overall branch support are improved. All newly added genera are assigned to earlier established tribes or the new tribe Paraphlomideae Bendiksby, which includes Ajugoides, Matsumurella and Paraphlomis. Acanthoprasium is resurrected as a genus. Transfer of species is proposed to ac- commodate the monophyly of two genera (Lamium, Otostegia), whereas ten genera remain non-monophyletic (Ballota s.str., Lagopsis, Leonotis, Leonurus, Leucas, Microtoena, Phlomoides, Sideritis, Stachys, Thuspeinanta). Eriophyton and Stachyopsis have been included in Lamieae, Hypogomphia in Stachydeae, and Loxocalyx in Leonureae. Betonica, Colquhounia, Galeopsis, and Roylea remain unclassified at the tribal level. Lamium chinense and three East Asian Galeobdolon species are transferred to Matsumurella. Sulaimania and four Otostegia species are transferred to Moluccella. Alajja and three Lamium species are transferred to Eriophyton. In total, 14 new combinations are made, one at the rank of subgenus and 13 at the rank of species.
125 citations
TL;DR: The use of a single generic name (Trametes) for the trametoid clade is considered to be the best taxonomic and nomenclatural option as the morphological concept of Trametes would remain almost unchanged, few new nomenClatural combinations would be necessary, and the classification of additional species based on morphological characters alone will still be possible.
Abstract: The phylogeny of Trametes and related genera was studied using molecular data from ribosomal markers (nLSU, ITS) and protein-coding genes (RPB1, RPB2, TEF1-alpha) and consequences for the taxonomy and nomenclature of this group were considered. Separate datasets with rDNA data only, single datasets for each of the protein-coding genes, and a combined five-marker dataset were analyzed. Molecular analyses recover a strongly supported trametoid clade that includes most of Trametes species (including the type T. suaveolens, the T. versicolor group, and mainly tropical species such as T. maxima and T. cubensis) together with species of Lenzites and Pycnoporus and Coriolopsis polyzona. Our data confirm the positions of Trametes cervina (= Trametopsis cervina) in the phlebioid clade and of Trametes trogii (= Coriolopsis trogii) outside the trametoid clade, closely related to Coriolopsis gallica. The genus Coriolopsis, as currently defined, is polyphyletic, with the type species as part of the trametoid clade and at least two additional lineages occurring in the core polyporoid clade. In view of these results the use of a single generic name (Trametes) for the trametoid clade is considered to be the best taxonomic and nomenclatural option as the morphological concept of Trametes would remain almost unchanged, few new nomenclatural combinations would be necessary, and the classification of additional species (i.e., not yet described and/or sampled for molecular data) in Trametes based on morphological characters alone will still be possible. Alternative scenarios to divide the trametoid clade in five or ten genera were considered but if any of these options were to be adopted morphological distinction of the segregated genera and the ascription of additional species to any of these genera would be very difficult and in some cases impossible. The genera Artolenzites, Coriolopsis (as currently typified), Coriolus, Cubamyces, Cyclomycetella, Lenzites, Poronidulus, Pseudotrametes and Pycnoporus are considered synonyms of Trametes.
107 citations
TL;DR: The molecular trees congruently resolve three major clades of unclear relationship within Camphorosmeae, Chenolea clade (five widely disjunct and morphologically divergent C3-species, possibly remnants of old lineages), Sclerolaena clade, and Bassia/Camphorosma clade which are widely distributed in Eurasia and southern Africa.
Abstract: Camphorosmeae constitute a species-rich tribe of Chenopodiaceae-Camphorosmoideae that consists mostly of subshrubs and annuals, distributed in steppes and semi-deserts of Australia, Eurasia, North Africa, southern Africa and North America. We study (1) the relationships of Camphorosmeae to major lineages of the closely related Salsoloideae and (2) the diversification of the tribe with focus on the non-Australian members using sequence variation of five different markers (rbcL gene, ndhF gene, atpB-rbcL spacer, psbB-psbH spacer, ITS) and morphological characters. The cpDNA analyses revealed six early-branching lineages in Camphorosmoideae/Salsoloideae (Camphorosmeae, Salsoleae s.str., Caroxyloneae, Salsola kali clade, Nanophyton clade, Salsola genistoides clade) and supported partly (ndhF and atpB-rbcL spacer) the sister-group relationship of Camphorosmeae and all Salsolean clades. The distinctness of Camphorosmeae and Salsoleae s.l. is further supported by seed, stigma and pollen morphology. Molecular clock estimates point to an earlier radiation in Salsoleae s.l. (Early to Middle Oligocene) than in Camphorosmeae (Early Miocene). In Salsoleae s.l. early radiation might have been enhanced by multiple evolution of C4-photosynthesis which facilitated the spread into drier habitats of Eurasia. In Camphorosmeae, C4-photosynthesis likely evolved two times, probably in the Middle Miocene. During the Miocene Camphorosmeae spread from Eurasia to Australia, North America and at least two times to South Africa. Only the Australian lineage diversified, the others remained species-poor. The molecular trees congruently resolve three major clades of unclear relationship within Camphorosmeae, Chenolea clade (five widely disjunct and morphologically divergent C3-species, possibly remnants of old lineages), Sclerolaena clade (ca. 150 C3-species from Central Asia [3 spp.] and Australia [147 spp.], probably the results of a rapid radiation during the Pliocene) and Bassia/Camphorosma clade (ca. 23 C4-species and one C3/C4-intermediate which are widely distributed in Eurasia and southern Africa). The phylogenies show the artificial state of the current generic and subtribal classifications of Eurasian, North American and South African Camphorosmeae. All non-monotypic genera except Camphorosma and Neokochia were found to be polyphyletic. A revised classification of the tribe is proposed including reinstatement of the newly defined subfamily Camphorosmoideae, description of the new genera Spirobassia (1 sp.), Eokochia (1 sp.), Grubovia (3 spp.) and Sedobassia (1 sp.), and several new combinations and synonymizations.
100 citations
TL;DR: The infrageneric classification of the New World species of Croton is updated with new evidence from phylogenetic analyses of DNA sequence data from all three genomes, and relationships of species that were previously placed in conflicting positions by nuclear and chloroplast data are resolved.
Abstract: Croton (Euphorbiaceae) is a large and diverse group of plants that is most species-rich in the tropics. We update the infrageneric classification of the New World species of Croton with new evidence from phylogenetic analyses of DNA sequence data from all three genomes. The relationships of species that were previously placed in conflicting positions by nuclear and chloroplast data, such as C. cupreatus , C. poecilanthus, and C. setiger , are further resolved by adding the nuclear EMB2765 and mitochondrial rps3 genes to the molecular sampling. Analyses of rps3 reveal an accelerated rate of evolution within Croton subg. Geiseleria , the only one of the four subgenera that contains numerous herbaceous, annual species. We provide morphological descriptions, species lists, and a key to the 31 sections and 10 subsections recognized in the New World. New taxa that we describe include C. sects. Alabamenses , Argyranthemi , Cordiifolii , Corinthii , Cupreati , Luetzelburgiorum , Nubigeni , Olivacei , Pachypodi , Prisci , and C. subsects. Cubenses , Jamaicenses , and Sellowiorum. Additional transfers are made to the ranks of subgenus, section, and subsection. A total of 712 species of Croton are currently recognized for the New World, with 702 of them assigned here to section.
95 citations
87 citations
TL;DR: A phylogenetic analysis that circumscribes the major clades within the spiny solanums and examines the relationships among them, with an emphasis on New World species, gives an increased understanding of the evolution of the Leptostemonic clade.
Abstract: Solanum subg. Leptostemonum contains approximately 350-450 species, including the cultivated eggplant, S. melongena. Most species placed in this subgenus form a monophyletic group, the Leptostemonum clade, characterized by the presence of stellate hairs and prickles, leading to the common name of "spiny solanums". Here we present a phylogenetic analysis that circumscribes the major clades within the spiny solanums and examines the relationships among them, with an emphasis on New World species. Of particular interest is the clarification of the clade limits and species composition of groups that have not been well-sampled. We also increase sampling of taxa that have been previously analyzed in molecular studies, namely those in the Torva, Micracantha, and Erythrotrichum clades. These groups have convergent morphological characteristics that have challenged taxonomists, making classification difficult. Results from our study delimit 14 clades within the spiny solanums, including the newly designated Asterophorum, Gardneri, Sisymbriifolium, and Thomasiifolium clades. We also establish the placement of species not previously sampled, especially those endemic to Brazil. These results give an increased understanding of the evolution of the Leptostemonum clade by defining monophyletic groups within it and identify areas of the phylogenetic tree that remain unresolved and require further taxon sampling.
TL;DR: The diversification of these groups in the Tibetan Plateau is of relatively young age, and can be explained by rapid diversification and radiation of the Soroseris-Stebbinsia clade, allopatric speciation within Syncalathium s.str.
Abstract: Soroseris, Stebbinsia, and Syncalathium are three genera of the sunflower family (Asteraceae) with restricted distributions on high screes of the Tibetan Plateau. We present a molecular analysis to test the monophyly of the genera, evaluate the phylogenetic relationships and construct their biogeographic diversification history. Nuclear ITS and plastid trnL-F and psbA-trnH fragments were analyzed with parsimony, Bayesian inference, and relaxed Bayesian dating for all species of Soroseris, Stebbinsia, and Syncalathium. Stebbinsia is part of a polytomy with several lineages of Soroseris. Syncalathium is biphyletic with Syn. souliei placed within subtribe Lactucinae and the remaining species close to the Soroseris-Stebbinsia clade within subtribe Crepidinae. Bayesian dating based on ITS sequences and using four fossil calibrations suggests that the stem and crown ages of the Soroseris-Stebbinsia clade and the two groups of Syncalathium are between 8.44 and 1.56 million years. Stebbinsia should be treated as a section of Soroseris and Syncalathium souliei should be excluded from Syncalathium and either placed in Lactuca s.l. or established as a new genus in Lactucinae. The remaining species are to be treated as Syncalathium s.str. in Crepidinae. The diversification of these groups in the Tibetan Plateau is of relatively young age, and can be explained by rapid diversification and radiation of the Soroseris-Stebbinsia clade, allopatric speciation within Syncalathium s.str. and convergent evolution of Syncalathium s.str. and Syn. souliei. The speciation events correlated with climatic change and fragmentation of scree habitats during the uplift of the Tibetan Plateau. Possible migration routes in Syncalathium s.str. from the northeast to the central and southern part of the Tibetan Plateau are suggested.
TL;DR: It is shown that the succulent species of Euphorbia have diversified over the last 36 million years into many of the semi-arid, tropical parts of the world and it is implied that these distributions arose by long-distance dispersal after the break-up of Gondwana.
Abstract: We use a relatively densely sampled phylogeny to obtain preliminary estimates for the ages of the major clades identi fied in Euphorbia, with which we show that the succulent species of Euphorbia have diversified over the last 36 million years into many of the semi-arid, tropical parts of the world. Many major clades have subclades from widely separated regions, often on different continents. Our results imply that these distributions arose by long-distance dispersal after the break-up of Gondwana. In the case of Indian/South-east Asian succulents there appears to have been a single, relatively recent dispersal event from Africa. We have included many species from the Arabian Peninsula and Socotra and we show that these are nested within other, mainly African clades. In some cases Arabian and Socotran taxa have their closest relatives in adjacent parts of North-east Africa and most often this is true in recent clades, while in more ancient clades their closest relatives may be in Macaronesia or in the Namib Desert of Southern Africa so that these are typical 'Rand Flora' elements. In one case, closest known relatives are in North America. We find that Socotran taxa vary between 16 and 3 Ma old. The major diversifications of succulents in temperate Southern Africa (the crown clades in subg. Rhizanthium and more minor clades in subg. Chamaesyce) and in tropical East Africa (the crown clades in subg. Euphorbia) occurred in the last 20-3 Ma. In the Greater Cape Flora of the western part of Southern Africa the diversity in Euphorbia is mainly derived from one lineage in subg. Rhizanthium and one in subg. Chamaesyce. In contrast the diversity of Euphorbia in the Arabian Peninsula is derived from the invasion (mainly from Africa) of many separate lineages. We show that large, succulent trees are only found in subg. Euphorbia and only occur in the Old World. Most of them fall within a single clade and have evolved relatively recently.
TL;DR: A densely sampled plastid gene tree is used for a morphologically complex group within the legume genus Mimosa to improve estimates of species limits and diversity in the poorly known dry inter-Andean valley of the Rio Marafion, northern Peru.
Abstract: Molecular phylogenies which include multiple accessions of species and near complete taxon sampling can be an important tool for estimating species diversity when used in combination with traditional morphology-based taxonomy. Here we use a densely sampled plastid gene tree for a morphologically complex group within the legume genus Mimosa (sect. Batocaulon ser. Andinae) to improve estimates of species limits and diversity in the poorly known dry inter-Andean valley of the Rio Maranon, northern Peru. Based on the plastid gene tree, Mimosa ser. Andinae, which previously comprised four species, is re-circumscribed to include six Andean dry-forest species from northern Peru, Ecuador and southern Colombia, including the new species, M. jaenensis, described here. A further three candidate species are identified within the section based on high levels of sequence variation among accessions. With the additional species, the Maranon valley is now known to harbour nine narrowly restricted endemic species of Mimosa, a pattern of multiple congeneric endemics mirrored in many other plant genera as well as several animal groups. Our results, in combination with other published studies, suggest that overall species diversity in the Maranon has been significantly under-estimated. Further work is needed to identify conservation priority areas in the Maranon in order to protect its unique flora.
TL;DR: The most-significant changes in the International Code of Botanical Nomenclature are outlined and three other papers are introduced presenting in more detail the nature and implications of some of the decisions taken.
Abstract: When decisions of a Nomenclature Section of an International Botanical Congress (IBC) are presented in Naturenews (Cressey, 2011) and prompt an editorial in the journal itself (Origin of species, 2011) they must be of unusual significance. This was indeed the case for several of those taken at the recent XVIII IBC in Melbourne, Australia. Changes to the International Code of Botanical Nomenclature (McNeill & al., 2006) require the decision of a plenary session of an IBC as proposed by its Nomenclature Section. The Nomenclature Section of the XVIII IBC met from 18 to 22 July 2011 in the University of Melbourne, and its decisions were approved by the final plenary session of that Congress on 30 July 2011, taking immediate effect except where otherwise limited (see below). We outline here the most-significant changes in the Code and introduce three other papers presenting in more detail the nature and implications of some of the decisions taken. Full details of the decisions of the Nomenclature Section on all the published proposals and of additional proposals made and accepted in Melbourne, along with the results of the preliminary mail vote, also appear in this issue (McNeill & al., 2011).
TL;DR: The Mediterranean and Irano-Turanian biogeographic regions are biodiversity hotspots for mesophytic and xerophytic species, including many Delphinieae, and the phylogeny of Consolida and Aconitella is inferred, using a Bayesian relaxed clock model to estimate divergence times and a maximum likelihood approach to reconstruct ancestral areas.
Abstract: The Mediterranean and Irano-Turanian biogeographic regions are biodiversity hotspots for mesophytic and xerophytic species, including many Delphinieae. This phylogenetically poorly understood tribe of Ranunculaceae consists of Consolida and Aconitella, with together ca. 52 species, and Delphinium and Aconitum, each with ca. 300 species. To infer the phylogeny of Consolida and Aconitella, we analyzed nuclear and chloroplast DNA sequences from 39 of their species and subspecies (44 taxa) plus a set of 30 exemplar species of Delphinium and Aconitum. We used a Bayesian relaxed clock model to estimate divergence times and a maximum likelihood approach to reconstruct ancestral areas. Aconitella forms a clade embedded in Consolida, and the latter is embedded in Delphinium. Consolida s.l. (including Aconitella) comprises two clades in the IranoTuranian region and three in the Mediterranean basin. The latter clades’ inferred crown ages of 5.1, 4.4, and 2.8 Ma suggests that the repeated drying-up of the Mediterranean, concomitant with and following the Messinian salinity crisis (5.96–5.33 Ma), may have facilitated their westward expansion. While there is clear geographic structure towards the tips of the Consolida s.l. tree, a likely ancestral area could not be inferred. However, the initial diversification of Consolida s.l., which occurred ca. 17 Ma ago, falls in a period when the climate in the Anatolian region became more arid, which may have favoured the annual life cycle that characterizes all species in this clade. To achieve a classification of mutually monophyletic genera in Delphinieae may require transferring the species of Aconitella and Consolida into Delphinium.
TL;DR: This study provides the first insight in the molecular phylogeny of the diploid D. fragrans, which shows major genetic variation within the only European population of the species.
Abstract: To test earlier hypotheses on the evolutionary origins of European polyploid Dryopteris, their phylogenetic rela- tionships are investigated using nuclear pgiC and plastid trnL-F sequence data. The nuclear pgiC region is for the first time used successfully in phylogenetic analyses of ferns, and is shown to provide appropriate variability to address species-level questions in Dryopteris. The trnL-F dataset is used to infer maternal relationships for the allopolyploid species and provides strong support for some of the smaller clades resolved by pgiC. Allopolyploid origins of Dryopteris carthusiana, D. cristata, and D. guanchica are supported and some, but not all, progenitors are indicated by the analyses. The results are in disagreement with the "D. semicristata" hypothesis proposed by several authors. The allopolyploid origin of D. crispifolia remained unresolved and allopolyploid origins of D. dilatata and D. filix-mas were unsupported. This study provides the first insight in the molecular phylogeny of the diploid D. fragrans, which shows major genetic variation within the only European population of the species.
TL;DR: The results showed that sect.
Abstract: Euphorbia subg. Esula (Euphorbiaceae) has recently been shown, using molecular analyses, to contain a clade with a disjunct distribution in Macaronesia, South Africa and the Eritreo-Arabian region, and being primarily made up of members of sect. Tithymalus subsect. Pachycladae and sect. Tirucalli. To delimitate this disjoint group, we carried out phylogenetic analyses of the internal transcribed spacer (nrITS) using a broad sampling, with emphasis on subg. Esula. Subsequently, we carried out phylogenetic analyses focused on this clade using nuclear (ITS, ETS) and chloroplast (trnL-trnF, psbA-trnH, ycf3-trnS, trnG, atpB-rbcL, trnK-matK, trnT-trnL) markers, with the aim of resolving the phylogenetic relationships within the group and reconstructing its biogeographic history. Our results showed that sect. Tithymalus subsect. Pachycladae and sect. Tirucalli are polyphyletic. Section Aphyllis is recircumscribed to comprise the Pachycladae core clade and part of sect. Tirucalli. Low resolution within sect. Aphyllis and incongruences between nuclear and chloroplast phylogenies may be due to hybridization. Section Aphyllis should have originated in the Mediterranean area; its disjunct distribution is probably due to vicariance, resulting from fragmentation of a wider distribution area in North Africa caused by the aridification of the climate during the late Miocene-Pliocene.
TL;DR: A phylogenetic analysis of 127 species using seven plastid regions to infer the evolutionary relationships of Centropodia, M. papposa, and M. rangei shows they are sister to the remaining tribes in Chloridoideae and provides the carbon isotope ratios for four species indicating that Merxmuellera pappos and M- rangei are photosynthetically C3, and CentropODia glauca and C. mossamdensis are C4.
Abstract: There has been confusion among taxonomists regarding the subfamilial placement of Merxmuellera papposa, M. rangei, and four species of Centropodia even though many researchers have included them in molecular studies. We conducted a phylogenetic analysis of 127 species using seven plastid regions (rps3, rps16-trnK, rps16, rpl32-trnL, ndhF, ndhA, matK) to infer the evolutionary relationships of Centropodia, M. papposa, and M. rangei with other grasses. Merxmuellera papposa and M. rangei form a clade that is sister to three species of Centropodia, and together they are sister to the remaining tribes in Chloridoideae. We provide the carbon isotope ratios for four species indicating that Merxmuellera papposa and M. rangei are photosynthetically C3, and Centropodia glauca and C. mossamdensis are C4. We present evidence in favor of the expansion of subfamily Chloridoideae to include a new tribe, Centropodieae, which includes two genera, Centropodia and a new genus, Ellisochloa with two species, Ellisochloa papposa and E. rangei. The name Danthonia papposa Nees is lectotypified.