Systematic placement and biogeographical relationships of the monotypic genera Gypothamnium and Oxyphyllum (Asteraceae: Mutisioideae) from the Atacama Desert

Gypothamnium and Oxyphyllum (Asteraceae) are two monotypic genera endemic to the Atacama Desert of northern Chile. We performed a phylogenetic analysis using published sequences of the plastid rbcL and ndhF genes, the trnL‐trnF region and the nuclear ribosomal internal transcribed spacer (ITS) to assess the systematic placement of the two genera within Mutisioideae. On the basis of the phylogenetic results, we constructed area cladograms to explore the biogeographical relationships and origin of the genera. The phylogenetic analysis showed that Gypothamnium is closely related to Aphylloclados, Plazia, Urmenetia, Lycoseris and Onoseris, whereas Oxyphyllum is closely related to Leucheria, Moscharia, Polyachyrus and, with low support, Jungia. These results do not differ substantially from those proposed in previous treatments based on morphological characters. The biogeographical analysis suggests that Gypothamnium in the coastal Atacama Desert is related to taxa that are currently distributed in eastern subtropical South America and in the Puna. Oxyphyllum may have originated from central Chile and other areas in southern South America, but its sister group (Leucheria + Polyachyrus) also reaches the Puna and the coastal Atacama Desert. Both groups show ancestral affinities with elements currently distributed in north‐western South America and Mesoamerica. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 32–51.     

Notes on African species of the genus Anisopappus Hook. & Arn. (Asteraceae)

Two new species of the genus Anisopappus Hook. & Arn. (Asteraceae) are described: A. athanasioides Paiva & Ortiz, from Angola, and A. pseudopinnaididus Ortiz & Paiva, from Namibia. The morphological variability of the A. chinensis-A. africanus complex is studied and two new combinations are proposed: A. chinensis subsp. africanus (Hook, fil.) Ortiz & Paiva and A. chinensis subsp. lobatus (Wild) Ortiz & Paiva.     

Notes on African species of the genus Anisopappus Hook. & Arn. (Asteraceae)

Two new species of the genus Anisopappus Hook. & Arn. (Asteraceae) are described A. athanasioides Paiva & Ortiz, from Angola, and A. pseudopinnatifidus Ortiz & Paiva, from Namibia. The morphological variability of the A. chinensia-A. africanus complex is studied and two new combinations are proposed: A. chinensis subsp. africanus (Hook. fil.) Ortiz & Paiva and A. chinensis subsp. lobatus (Wild) Ortiz & Paiva.     

Karyotype evolution in South American species of Hypochaeris (Asteraceae, Lactuceae)

The genus Hypochaeris (Asteraceae, Lactuceae) contains ten species in Europe, three in Asia, and approximately 50 in South America. Previous cytotaxonomic studies have shown two groups of taxa: (1) European species with different basic chromosome numbers and differentiated karyotypes, and (2) South American species with x=4 and uniform asymmetric and bimodal karyotypes. Karyotypic data are synthesized for South American species of Hypochaeris with new information for six Chilean species: H. acaulis, H. apargioides, H. palustris, H. spathulata, H. tenuifolia and H. thrincioides. Four main groups can be distinguished based on presence and localization of secondary constrictions – SCs (bearing Nucleolar Organizer Regions – NORs) on chromosomes 2 and 3, and 18S–25S and 5S rDNA loci number, localization, and activity. We propose karyotypic evolution of South American Hypochaeris (x=4) from H. maculata-like (x=5) European ancestors. The original South American karyotype would have possessed two SCs, one on the long arm of chromosome 2, and the other on the short arm of chromosome 3 (in terminal position). Further evolution would have involved inversion within the short arm of chromosome 3 and inactivation/loss of the SC on chromosome 2.     

Eine neue tropische Unterart von Keratella cochlearis (Rotatoria)

A new subspecies of Keratella cochlearis, viz. Keratella cochlearis pachyacantka is described. It has been recorded from Africa and South America.     

Pleistocene refugia and recolonization routes in the southern Andes: insights from Hypochaeris palustris (Asteraceae, Lactuceae)

Hypochaeris palustris (Phil.) De Wild. is a species growing in the southern Andean chain. To elucidate potential Pleistocene refugia and recolonization routes in the southern Andes, we analysed amplified fragment length polymorphisms (AFLPs) in 206 individuals in 21 populations of H. palustris from the coastal Cordillera, the central, northern, and eastern ranges of the southern Andes, and Patagonia. Populations from the coastal Cordillera harboured more private AFLP fragments, and exhibited a higher frequency of polymorphic fragments as well as higher Shannon diversity than all other areas investigated. The comparison among pooled AFLP profiles of each region revealed that the central Andean ranges shared most fragments with populations from the margins of the distributional area in the Andes, in the N, E, and S (Patagonia). Phenetic analysis indicated close relationships among populations of the central ranges. Populations of the coastal Cordillera were shown to be highly differentiated from the Andean populations. It is very likely therefore that (1) H. palustris recolonized the central ranges of the southern Andes from nearby refugia, possibly unglaciated areas N, E, and/or S of its present distributional area; (2) the postglacial spread of H. palustris in the central ranges of the southern Andes occurred rapidly; and (3) the coastal Cordillera served as a refugium for H. palustris, but these populations did not contribute to the recolonization of the central Andean ranges.     

Isozymes, and the status of Taraxacum (Asteraceae) agamospecies

HUGHES, L. & RICHARDS, A. J., 1989. Isozymes and the status of Taraxacum (Asteraceae) agamospecies. Genetic identities I and Similarity Indices SI are calculated between 12 samples of Taraxacum, on the basis of 40 isozymes at 15 loci for 10 enzyme systems. Samples included three polyploid agamospermous populations from northern England (group 1), three sexual diploid populations from south-central France (group 2), and six accessions of ‘primitive’ diploid self-compatible sexual taxa from southern Europe and Australia. Samples could be assigned to eight species, classified in seven sections of the genus. Two clusters of high relationship were evident. All the group 1 and group 2 species were very closely related, with pairwise comparisons for I in excess of 0.93. The three group 3 accessions identified as T. bessarabicum showed pairwise comparisons for SI in excess of 0.71. Comparisons for SI between the other group 3 species, and between all the group 3 species and the group 1 and 2 species were all very low, not exceeding 0.45. It is concluded that dissimilarity between samples as assessed by isozymes is probably related to the time of evolutionary divergence of those samples. Although allopolyploid, and morphologically very diverse, the group 1 agamospecies may have very recently diverged asexually from a common stock. The group 2 diploids may have resulted from rediploidization and regained sexuality from the same originally agamospermous stock. In areas of Europe in which such ‘modern’ sexuality is common, it is probable that all ‘modern’ Taraxaca, including at least five sections of the genus, should be included within a single taxon. In contrast, ‘primitive’ self-compatible sexual species in group 3 appear to have diverged from each other several million years ago, and with the exception of the disjunct accessions of T. bessarabicum, are genetically highly distinct. Such species should be maintained in the taxonomies of all areas. It is probable that an agamospecies classification of ‘modern’Taraxacum will continue to convey much useful information in areas, such as northern Europe, in which sexuality is absent.     

Phylogenetic implications of corolla morphology in subfamily Barnadesioideae (Asteraceae)

The previously insignificant and small South American subtribe Barnadesiinae of tribe Mutisieae has been shown recently to be ancient within Asteraceae. Due to absence of a 22 kb diagnostic chloroplast inversion, plus other features, this subtribe has been elevated to subfamilial status as Barnadesioideae, now containing 90 species in nine genera. Recent cladistic analyses at the generic and specific levels based on morphology and DNA sequences (ITS and trnL intron) have revealed different relationships among taxa of the subfamily. To better understand these conflicts, we analyze specific morphological features of corollas (shape and vascularization) to develop trends (trees) in these features based on minimal structural change (i.e., morphological parsimony), and to compare these with relationships among genera derived from the two recent cladistic analyses. We define six principal types of corollas in Barnadesioideae (tubular, split, double split, ligulate, subbilabiate and bilabiate) and six principal types of corolla vascularization patterns (combinations of presence or absence of central bundles, fusion of adjacent bundles and fusion of bundles at the apex of corolla lobes). In all features we assume character states in Calyceraceae to be ancestral. In corolla shape, from tubular ancestry, we hypothesize two general evolutionary trends within the subfamily: (1) splitting of the tube, and (2) flattening of the tube. In vascularization of corollas, from an ancestral condition of one central and one lateral bundle in each corolla lobe and all traces fused at the apex, we hypothesize four basic trends: (1) gain or (2) loss of lateral vascular traces in each lobe, (3) loss of the central vein, and (4) loss of fusion of traces in lobe apices. These morphological trends allow tests of the two previous phylogenetic hypotheses by (1) counting step changes (following steps in the morphological network) in the two characters on the two competing phylogenetic trees and (2) constructing an index of morphological advancement for each genus (based on morphological trees of the two characters) and correlating these with cladistic distances within the two phylogenies. Results of both tests reveal the molecular phylogeny to be more compatible with evolutionary inferences from the two morphological features. With Fulcaldea excluded, a highly significant correlation is seen between morphological advancement and cladistic distance in the molecular phylogeny.     

Karyotype diversification and evolution in diploid and polyploid South American Hypochaeris (Asteraceae) inferred from rDNA localization and genetic fingerprint data

Background and Aims: Changes in chromosome structure and number play an importantrole in plant evolution. A system well-suited to studying differentmodes of chromosome evolution is the genus Hypochaeris (Asteraceae)with its centre of species' diversity in South America. AllSouth American species uniformly have a chromosome base numberof x = 4 combined with variation in rDNA number and distribution,and a high frequency of polyploidy. The aim of this paper isto assess directions and mechanisms of karyotype evolution inSouth American species by interpreting both newly obtained andprevious data concerning rDNA localization in a phylogeneticcontext. Methods: Eleven Hypochaeris species from 18 populations were studiedusing fluorescence in situ hybridization (FISH) with 35S and5S rDNA probes. A phylogenetic framework was established fromneighbour-net analysis of amplified fragment length polymorphism(AFLP) fingerprint data. Key Results: A single 5S rDNA locus is invariably found on the short armof chromosome 2. Using 35S rDNA loci, based on number (one ortwo) and localization (interstitial on the long arm of chromosome2, but sometimes lacking, and terminal or interstitial on theshort arm of chromosome 3, only very rarely lacking), sevenkaryotype groups can be distinguished; five of these includepolyploids. Karyotype groups with more than one species do notform monophyletic groups. Conclusions: Early evolution of Hypochaeris in South America was characterizedby considerable karyotype differentiation resulting from independentderivations from an ancestral karyotype. There was marked diversificationwith respect to the position and evolution of the 35S rDNA locuson chromosome 3, probably involving inversions and/or transpositions,and on chromosome 2 (rarely 3) concerning inactivation and loss.Among these different karyotype assemblages, the apargioidesgroup and its derivatives constitute by far the majority ofspecies.     

Elucidative studies on the generic concept of Senecio (Asteraceae)

VINCENT, P. L. D. & GETLIFFE, F. M., 1992. Elucidative studies on the generic concept of Senecio (Asteraceae) . This paper presents the results of studies of the generic concept of Senecio sensu stricto. The sample of taxa studied consisted of 93 Natal senecios (including seven varieties and two forms), five Cape heterochromous senecios and nine non-southern African senecios, including the type of the genus, S. vulgaris L. Also included in the study were six species from taxonomically closely related genera in the tribe Senecioneae and one Senecio of uncertain taxonomic position. The phenotype of these taxa was investigated with respect to a large number (122) of morphological and micromorphological characters. Six characters were selected as being taxonomically important with respect to elucidating the generic concept of Senecio sensu stricto. The generic concept of Senecio has been provisionally re-circumscribed and the generic status of each of the senecios and non-senecios studied has been tested according to this concept of Senecio sensu stricto sensu Vincent. In the light of this concept of Senecio , the following species are recommended for exclusion from Senecio sensu stricto sensu Vincent: S. cissampelinus, S. transvaalensis, S. syringifolius and S. hockii. The following species are considered to be peripheral to Senecio sensu stricto sensu Vincent: S. tanacetopsis, S. seminiveus, S. medley-woodii, S. tamoides, S. helminthioides, S. barbertonicus, S. brevilorus, S. viminalis, S. radicans and S.fulgens. Before any taxonomic changes are made to the current composition of Senecio , the concept of Senecio sensu stricto sensu Vincent, is being tested on a worldwide sample of the genus.     

Karyological evolution in Rhaponticum Vaill. (Asteraceae, Cardueae) and related genera

Chromosome counts are reported in 29 populations representing 20 species and one subspecies of the genera Callicephalus (one sp.), Klasea (seven spp.), Myopordon (two spp.), Oligochaeta (one sp.), and Rhaponticum (nine spp., one ssp.). Eleven reports are new, the others supplement limited previous data. New and published cytological data are summarized and evaluated critically in light of current taxonomic treatments and evolutionary hypotheses. Basic chromosome numbers are a valuable source of taxonomic information and relate well to the phylogeny. They are quite conserved in Klasea (only x  = 15), the sister group of the remaining genera, and in the early branching genera of the Rhaponticum group ( x  = 14 for Centaurothamnus and Callicephalus ). However, a more complex pattern of genome evolution is present among the more derived clades, Oligochaeta plus Myopordon ( x  = 12, 14) and the genus Rhaponticum ( x  = 12, 13). The occurrence of x  = 12 in Oligochaeta divaricata and Rhaponticum carthamoides seems to be the result of a recent event of chromosome fusion, as suggested by the fragility of particularly long pairs of chromosomes. The use of chromomycin staining, including an enzymatic digestion step that facilitates spreading and permits a reduction of potential fragmentation, only partially resolves this problem.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 153 , 193–201.     

Floral development and evolution of capitulum structure in Anacyclus (Anthemideae,Asteraceae)

Background and Aims

Most of the diversity in the pseudanthia of Asteraceae is based on the differential symmetry and sexuality of its flowers. In Anacyclus, where there are (1) homogamous capitula, with bisexual, mainly actinomorphic and pentamerous flowers; and (2) heterogamous capitula, with peripheral zygomorphic, trimerous and long-/short-rayed female flowers, the floral ontogeny was investigated to infer their origin.

Methods

Floral morphology and ontogeny were studied using scanning electron microscope and light microscope techniques

Key Results

Disc flowers, subtended by paleae, initiate acropetally. Perianth and androecium initiation is unidirectional/simultaneous. Late zygomorphy occurs by enlargement of the adaxial perianth lobes. In contrast, ray flowers, subtended by involucral bracts, initiate after the proximal disc buds, breaking the inflorescence acropetal pattern. Early zygomorphy is manifested through the fusion of the lateral and abaxial perianth lobes and the arrest of the adaxials. We report atypical phenotypes with peripheral ‘trumpet’ flowers from natural populations. The peripheral ‘trumpet’ buds initiate after disc flowers, but maintain an actinomorphic perianth. All phenotypes are compared and interpreted in the context of alternative scenarios for the origin of the capitulum and the perianth identity.

Conclusions

Homogamous inflorescences display a uniform floral morphology and development, whereas the peripheral buds in heterogamous capitula display remarkable plasticity. Disc and ray flowers follow different floral developmental pathways. Peripheral zygomorphic flowers initiate after the proximal actinomorphic disc flowers, behaving as lateral independent units of the pseudanthial disc from inception. The perianth and the androecium are the most variable whorls across the different types of flowers, but their changes are not correlated. Lack of homology between hypanthial appendages and a calyx, and the perianth double-sided structure are discussed for Anacyclus together with potential causes of its ray flower plasticity.     

An extinct Eocene taxon of the daisy family (Asteraceae): evolutionary, ecological and biogeographical implications

Background and Aims

Morphological, molecular and biogeographical information bearing on early evolution of the sunflower alliance of families suggests that the clade containing the extant daisy family (Asteraceae) differentiated in South America during the Eocene, although palaeontological studies on this continent failed to reveal conclusive support for this hypothesis. Here we describe in detail Raiguenrayun cura gen. & sp. nov., an exceptionally well preserved capitulescence of Asteraceae recovered from Eocene deposits of northwestern Patagonia, Argentina.

Methods

The fossil was collected from the 47·5 million-year-old Huitrera Formation at the Estancia Don Hipólito locality, Río Negro Province, Argentina.

Key Results

The arrangement of the capitula in a cymose capitulescence, the many-flowered capitula with multiseriate–imbricate involucral bracts and the pappus-like structures indicate a close morphological relationship with Asteraceae. Raiguenrayun cura and the associated pollen Mutisiapollis telleriae do not match exactly any living member of the family, and clearly represent extinct taxa. They share a mosaic of morphological features today recognized in taxa phylogenetically close to the root of Asteraceae, such as Stifftieae, Wunderlichioideae and Gochnatieae (Mutisioideae sensu lato) and Dicomeae and Oldenburgieae (Carduoideae), today endemic to or mainly distributed in South America and Africa, respectively.

Conclusions

This is the first fossil genus of Asteraceae based on an outstandingly preserved capitulescence that might represent the ancestor of Mutisioideae–Carduoideae. It might have evolved in southern South America some time during the early Palaeogene and subsequently entered Africa, before the biogeographical isolation of these continents became much more pronounced. The new fossil represents the first reliable point for calibration, favouring an earlier date to the split between Barnadesioideae and the rest of Asteraceae than previously thought, which can be traced back at least 47·5 million years. This is the oldest well dated member of Asteraceae and perhaps the earliest indirect evidence for bird pollination in the family.     

Comparative pappus micromorphology of edelweiss (Leontopodium,Gnaphalieae, Asteraceae) with implications for taxonomy,ecology and evolution

We analysed pappus characters in 31 of the c. 34 accepted Leontopodium spp. (edelweiss). Micromorphological pappus character states were useful for discriminating between individual species and intrageneric groups. The pappus differs in number, length, breadth, surface structure, colour and the tips of the bristles. Several features characterize single species, for example a unique fan‐like tip that is only found in L. franchetii. Leontopodium section Nobilia is supported by unusual pappus characters. Experimental evidence shows that the pappus of Leontopodium, previously thought to be caducous, is well suited for wind dispersal of the fruit. One clear trend is that species growing in sparsely vegetated, high‐altitude regions often have more numerous and longer pappus bristles, particularly on the female flowers.     

A taxonomic revision of Centaurea section Acrocentron (Asteraceae) in Iran

The taxonomic status of Centaurea section Acrocentron in Iran is briefly reviewed. A critical study of 251 herbarium specimens, and an additional 37 accessions collected specifically for this research, led to the discovery of a new variety, Centaurea irritans var. longispinosa Montazerolghaem , and the revival of another, C. persica var. subinermis, a taxon previously treated as a synonym for about 25 years. A key to all Iranian species of Centaurea section Acrocentron is provided. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 163 , 99–106.