Two new species of Vernonia (Asteraceae: Vernonieae) from Peru

Two new species,Vernonia sagasteguii andV. paucartambensis, from Peru are described, illustrated, and their relationships discussed.     

Cytotaxonomy of some species of the South American genus Lessingianthus (Asteraceae, Vernonieae)

Mitotic chromosome numbers of 32 populations belonging to 23 species of the genus Lessingianthus H.Rob. (Vernonieae, Asteraceae) were determined. The chromosome number of all examined plants was found to be based on x = 16. The numbers observed varied from 2n = 32 to 2n = 176. The results include the first report of the chromosome number for 11 species: L. lanatus (2n = 32), L. varroniifolius (2n = 32), L. cataractarum (2n = 64), L. intermedius (2n = 64), L. argenteus (2n = 96), L. centauropsideus (2n = 96), L. profusus (2n = 96), Lessingianthus sp. nov. 1 (2n = 96), Lessingianthus sp. nov. 2 (2n = 128), L. robustus (2n = 160), and L. macrocephalus (2n = 176). New chromosome numbers were found in the four other species: L. rubricaulis, L. laniferus, and L. sellowii were tetraploid with 2n = 64, while L. oxyodontus was hexaploid with 2n = 96. B chromosomes were observed in L. coriaceus and L. varroniifolius. Lessingianthus macrocephalus (2n = 11x = 176) is reported as the first case of an odd polyploid and the higher chromosome number of Lessingianthus. The significance of the results is discussed in relation to chromosomal data available for the genus.     

A new species of Lessingianthus (Asteraceae: Vernonieae) from Minas Gerais, Brazil

Lessingianthus ibitipocensis, a new species from the Southeastern Brazilian highlands, is described and illustrated.

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Resumen  Se describe e ilustra una especie nueva, Lessingianthus ibitipocensis, del sudeste de Brasil.

     

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.     

Vernoguinosterol and vernoguinoside, trypanocidal stigmastane derivatives from Vernonia guineensis (Asteraceae)

Two bitter stigmastane derivatives, vernoguinosterol (1) and vernoguinoside (2), have been isolated from the stem bark of Vernonia guineensis and their structures eludicated using spectroscopic methods. The new compounds exhibit trypanocidal activity.     

Stigmastane derivatives and isovaleryl sucrose esters from Vernonia guineensis (Asteraceae)

Vernoguinoside, 16beta,22R;21,23S-diepoxy-3beta-O-beta-D-glucopyranosyloxy-21S,24-dihydroxy-5alpha-stigmasta-8,14-dien-28-one (1), a new stigmastane derivative, 16beta,22R;21,23S-diepoxy-21S,24-dihydroxy-5alpha-stigmasta-8,14-diene-3,28-dione (2) and two new sucrose esters, 1',3,3',4',6'-pentakis-O-(3-methylbutanoyl)-beta-D-fructofuranosyl alpha-D-glucopyranoside (3) and 1',2,3',6,6'-pentakis-O-(3-methylbutanoyl)-beta-D-fructofuranosyl alpha-D-glucopyranoside (4), have been isolated from the stem bark of Vernonia guineensis. The structures of the new compounds were determined on the basis of spectroscopic evidence.     

Chromosome Numbers and Karyotypes of Species of Vernonia sect. Lepidaploa (Asteraceae: Vernonieae)

Vernonia is the largest genus of the tribe Vernonieae (Asteraceae) and comprises more than 1,000 species. In the present study we explore chromosome number and karyotype variation of eight species treated within different subsections of the section Vernonia sect. Lepidaploa. We aimed to explore if these data support the recognition of a single large genus (sensu Baker) or favor its splitting into 22 small genera (sensu Robinson). The species were collected in ??cerrado??, rupicolous and disturbed areas in the states of S?o Paulo and Minas Gerais, Brazil. Chromosome numbers varied from 2n?=?32 to 60. Most chromosomes were small, and the karyotype analysis revealed a predominance of metacentric and some submetacentric chromosomes. The karyotype symmetry in Vernonia was moderate (TF% 32.2 to 45.9), with the most symmetrical karyotype observed in V. rubriramea. The results obtained here did not conclusively support any of the taxonomic proposals for Vernonia due to the absence of distinctive or characteristic karyotype patterns for any of the taxonomic groupings, i.e., sections and subsections (sensu Baker) or new genera (sensu Robinson). Nevertheless, a tenuous relationship was observed between the chromosome numbers reported in the literature, those recorded here, and the taxonomic alterations suggested by Robinson for the genera Lessingianthus, Chrysolaena, and Vernonanthura that were originally part of Vernonia sensu Baker.     

Palynological survey of the subtribe Elephantopinae (Asteraceae, Vernonieae)

Despite the taxonomic value of pollen morphology within the tribe Vernonieae, a detailed study of the pollen of the subtribe Elephantopinae is still lacking. The pollen morphology of ten species, representing three of the four genera of the subtribe, Elephantopus, Pseudoelephantopus and Orthopappus, was studied with LM, SEM, and TEM. The pollen of all the species studied was found to be echinolophate, although the differences in aperture features and both sculpture and exine structure allowed recognizing two pollen types. The species of Elephantopus (except for E. elongatus) and Pseudoelephantopus share the regular or more or less regular ridges pattern, the colporate condition but with the ectoapertures little developed, and the acaveate exine structure. From the sculpture and the apertures, the pollen of Caatinganthus harleyi was found to be similar to that of Elephantopus and Pseudoelephantopus. The pollen morphology of the monotypic Orthopappus, which is shared with that of E. elongatus, was further investigated for the first time. We found that it differs from that of the other species in having an irregular pattern of ridges, colporate condition but with a well-developed ectoapertures, and caveate exine. Additional studies of the exine structure and apertures features, coupled with molecular phylogeny, are needed to understand the evolution of pollen characters and re-evaluate the intergeneric relationships within the tribe.     

Revision of Vernonia Series Flexuosae (Compositae: Vernonieae)

SeriesFlexuosae consists of eight closely related species. The taxa are collectively unique in their morphology and share similar flavonoid compounds. They range from south-central Brazil southwest into Bolivia, Paraguay, Uruguay and Argentina. The eight species are keyed, described and mapped and synonymies are provided.     

Grindelia mendocina (Asteraceae, astereae), a new South American species

Taxonomic revision of South American species of Grindelia Willd. has revealed a new species from Argentina, with homogamous capitula and cushion-shaped habit. The taxon is here described and illustrated.     

Population genetic structure of the South American species Hypochaeris lutea (Asteraceae)

The genus Hypochaeris has a recent evolutionary history caused by long‐distance dispersal in conjunction with adaptive radiation in the South American continent. Hypochaeris lutea is a perennial herb that grows mostly at altitudes of around 1000 m in cold swamps of the southern regions of Brazil. We investigated the amplified fragment length polymorphism (AFLP) in 270 individuals representing 11 Brazilian populations of H. lutea to elucidate the population genetic structure of this species. The frequencies of polymorphic loci and gene diversity ranged from 83.42% to 91.66% and from 0.26 to 0.34, respectively. Analysis of molecular variance revealed that most of the genetic variability was found within (76.67%) rather than among (23.3%) populations, agreeing with the pattern of genetic distribution within and among populations observed in other allogamous species of Hypochaeris. A Mantel test showed no correlation between genetic and geographic distances when all populations were considered. Simulations performed using a Bayesian approach consistently identified two clusters with different admixture proportions of individuals, as also revealed by a UPGMA dendrogram of populations. The pattern of genetic structure observed in H. lutea is consistent with a process of successive colonization events by long‐distance dispersal resembling the rapid and recent radiation that has been proposed to explain the origin of the South American species of Hypochaeris.     

Nuclear DNA content in some species of Lessingianthus (Vernonieae, Asteraceae) by flow cytometry

The nuclear DNA content was determined for the first time in 25 species of the South American genus Lessingianthus H.Rob. (Vernonieae, Asteraceae) by flow cytometry. This analysis constitutes the first estimation of the genome size for the Vernonieae tribe. The 2C- and 1Cx-values were calculated in all the species. The 2C-value ranged from 2.04 to 14.34 pg. The 1Cx-value ranged from 0.995 to 1.43 pg. The general tendency indicated a decrease in the 1Cx-value with increasing ploidy level, with some exceptions, in some species the 1Cx-value increased with the ploidy increase. The measuring of DNA content allowed reporting a new cytotype for L. polyphyllus (Sch.Bip.) H.Rob.     

Additions to South American Senecioneae (Asteraceae)

Three new Peruvian species belonging to the tribe Senecioneae (Asteraceae) are described, illustrated and their relationships discussed:Gynoxys colanensis, G. lopezii, andPentacalia barbourii.     

A revision of Vernonia series Buddleiifoliae (Compositae: Vernonieae)

SeriesBuddleiifoliae of the genusVernonia of southeastern South America consists of 18 species which are keyed, described, discussed and mapped.Vernonia goiasensis is proposed as a new name, whileV. wasshausenii andV. monocephala subsp.irwinii are described as new taxa, and V.asteriflora subsp.kuntzei is presented as a new combination.     

Three New Species of Vernonia (Compositae: Vernonieae) from Mexico

Three new Mexican species ofVernonia,V. macphersonii,V. pugana andV. tequilana, are described.     

Floral microcharacters in Lessingianthus (Vernonieae,Asteraceae) and their taxonomic implications

Micromorphological characters of 113 species of the South American genus Lessingianthus H.Rob. (Vernonieae, Asteraceae) were analyzed to evaluate their reliability as taxonomic markers. The corolla pubescence was studied in detail for the first time in the genus. Glandular and non-glandular trichomes were studied and described. The trichome types allow differentiation among related species, but do not reflect the relationships among species groups. On the other hand, the basal stylar node only occurs in a distinctive group of species within the genus. The apical appendage of the anthers is non-glandular in all species of the genus. Several character states analyzed in Lessingianthus are often widespread in other related genera of Vernonieae. Therefore, Lessingianthus can be circumscribed only by a combination of micro- and macromorphological features.     

Trypanocidal activity of Lychnophora staavioides Mart. (Vernonieae, Asteraceae)

In the continuing search for new compounds with trypanocidal activity for use in blood banks to prevent the transmission of Chagas' disease, a trypanocidal extract of Lychnophora staavioides Mart. (Vernonieae, Asteraceae) was fractionated using several chromatographic techniques and afforded the following flavonoids: tectochrysin, pinostrobin, pinobanksin, pinobanksin 3-acetate, pinocembrin, chrysin, galangin 3-methyl ether, quercetin 3-methyl ether, chrysoeriol and vicenin-2. The most active compound was quercetin 3-methyl ether, which showed no blood lysis activity and which represents a promising compound for use against T. cruzi in blood banks.     

Hieracium busambarense,a new species of the sect. Grovesiana (Asteraceae) from Sicily (Italy)

Hieracium busambarense (Asteraceae), a new species from calcareous-dolomite cliffs of Rocca Busambra (western Sicily, Italy) is described and illustrated here.     

Karyological features and cytotaxonomy of the tribe Vernonieae (Asteraceae)

Chromosome numbers are reported for 29 populations of 19 Vernonieae taxa collected mainly in the northeastern region of Brazil. Among them, data for five genera (Blanchetia, Rolandra, Pithecoseris, Stilpnopappus and Vanillosmopsis) are here reported for the first time, and the first chromosome counts are presented for 12 species. Chromosome numbers are quite diverse among and sometimes within genera, especially in the controversial and large subtribe Vernoniinae. The numbers varied from 2n = 18 to 2n = ~72. The main karyoevolutionary mechanism seems to be dysploidy, while polyploidy is probably associated with ancient hybridization processes generating most paleotetraploid genera. All studied species presented semi-reticulated interphase nuclei and proximal-early condensing behavior in prophase to prometaphase. In one species (Vernonia condensata with 2n = 40) fluorochrome staining with CMA/DAPI revealed five chromosome pairs bearing subterminal CMA⁺/DAPI^? heterochromatin, probably NOR-associated, revealing the existence of low amounts of satellite DNA. The role of these features in the evolution of the tribe is discussed, revealing some interesting aspects for understanding of the Vernonieae karyoevolution, especially regarding neotropical members.     

A systematic study of the Vernonia leopoldi complex (Compositae — Vernonieae)

A systematic study of the Vernonia leopoldi complex was undertaken with the objective of determining the taxonomic status of the species involved within this group. TWo species, i.e. Vernonia leopoldi and V. bipontini have been recognized as distinct based on evidence from morphological studies accompanied by field observations and anatomical studies (particularly trichomes and petioles). Both species have 2n = 36 (first reports). Three new varieties have been recognized within V. bipontini , namely var. bipontini , var. gonderensis and var. caccaensis . A lectotype is selected for V. leopoldi .