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Stucky Jon - One of the best experts on this subject based on the ideXlab platform.

Mark T. Strong - One of the best experts on this subject based on the ideXlab platform.

  • Rhynchospora belizensis (Cyperaceae), a new species of Rhynchospora sect. Tenues from Belize
    Brittonia, 2019
    Co-Authors: Robert F. C. Naczi, Pedro José Sanches Filho, Mark T. Strong, Wayt Thomas
    Abstract:

    The new species, Rhynchospora belizensis, is described, illustrated, and compared with phylogenetically closely related and morphologically similar species. Rhynchospora belizensis is known only from southern Belize, where it inhabits sunny, very wet, nutrient-poor, peaty ground of graminoid-dominated, gently sloping hillside seepages. It is unique in its combination of great height, aristate scales, achenes with relatively long stipes, and relatively low and faint transverse ridges on the faces. Vulnerable status appears warranted for R. belizensis because only two populations and fewer than 500 individuals are known, all within a small geographic area. DNA sequence data from the plastid marker trnL-trnF and nuclear markers ETS and ITS diagnose a clade of R. belizensis, its sister R. emaciata, and R. junciformis and R. saxisavannicola. Rhynchospora belizensis is the only member of this clade occurring in Central America; all the others are endemic to South America.

  • in the Guianas, South America by
    2016
    Co-Authors: Mark T. Strong
    Abstract:

    Strong, Mark T. Taxonomy and distribution of Rhynchospora (Cyperaceae) in the Guianas, South America. Contributions from the United States National Herbarium, volume 53, 225 pages (including 88 figures). Seventy-seven species and three infraspecific taxa in 19 sections of Rhynchospora Vahl nom. conserv. (Cyperaceae) are found to occur in the Guianas (Guyana, Suriname, and French Guiana), South America. A new section, Stipitatae M. T. Strong is described. Two synonyms of accepted taxa are lectotypified: Rhynchospora filiformis var. latifolia Uittien and Rhynchospora graminea Uittien. The species were taxonomically evaluated and circumscribed based on laboratory studies of micromorphological achene characters utilizing SEM, morphological herbarium studies of dried specimen collections, information on relationships between species from other studies published in the literature, habitat characterization, and distribution patterns. The infrageneric classification of Rhynchospora is discussed and morphological characteristics of the genus and recent cytological advances are reviewed. A taxonomic treatment is provided that includes a key to species, full detailed descriptions, distribution maps, SEM photomicrographs of all 80 taxa including images of the whole achene (fruit) and detail of the pericarp, line drawings fo

  • Rhynchospora Guaramacalensis,una nueva especie de Rhynchospora sección Paniculatae (Cyperaceae) de Venezuela
    2006
    Co-Authors: Mark T. Strong
    Abstract:

    RESUMEN Se describe e ilustra a  Rhynchospora guaramacalensis M.T.Strong, una especie nueva de  Rhynchospora seccion Paniculatae Boeck. (Cyperaceae) procedente del estado Trujillo, Venezuela. Se presenta una discusion de las diferencias entre este nuevo taxon y  R. macrochaeta , especie a la cual esta cercanamente relacionado. ABSTRACT The new species  Rhynchospora guaramacalensis M.T.Strong is described in  Rhynchospora section Paniculatae Boeck. (Cyperaceae) from Trujillo State, Venezuela. An illustration is provided and discussion of differences between it and  R. macrochaeta ,a closely related taxon, is given.

  • Rhynchospora GUARAMACALENSIS, UNA NUEVA ESPECIE DE RhynchosporaSECCIÓN PANICULATAE (CYPERACEAE) DE VENEZUELA Rhynchospora guaramacalensis, a new species of Rhynchospora section Paniculatae (Cyperaceae) from Venezuela
    2006
    Co-Authors: Mark T. Strong
    Abstract:

    The new species Rhynchospora guaramacalensisM.T.Strong is described in Rhynchosporasection Paniculatae Boeck. (Cyperaceae) from Trujillo State, Venezuela. An illustration is provided and discussion of differences between it and R. macrochaeta ,a closely related taxon, is given.

  • Novelties in Rhynchospora (Cyperaceae) from the Guianas
    Novon a journal of botanical nomenclature from the Missouri Botanical Garden, 2001
    Co-Authors: Mark T. Strong
    Abstract:

    Five new species are described (R. angustipaniculata, R. ayangannensis, R. bakhuisensis, R. donselaarii, and R. rupicola) and a new name proposed (R. pubisquama) in Rhynchospora Vahl nom. cons. from northeastern South America (Guianas). Illustrations are provided for the new species, their classification is determined, and a discussion of related species is given for each.

Krings Alexander - One of the best experts on this subject based on the ideXlab platform.

Thornhill Robert - One of the best experts on this subject based on the ideXlab platform.

Modesto Luceño - One of the best experts on this subject based on the ideXlab platform.

  • Morphological and genomic characterization of Rhynchospora tenuis complex (Cyperaceae) and its taxonomic implications
    Rodriguésia, 2012
    Co-Authors: Vanessa Silva Michelan, Modesto Luceño, Rafael Trevisan, Rogério Fernandes De Souza, Carlos Roberto Maximiano Da Silva, André Luís Laforga Vanzela
    Abstract:

    Species of Rhynchospora sect. Tenues are morphologically very similar. Rhynchospora tenuis complex is the most problematic species complex in this group and it concentrates entities of difficult delimitation, as is the case of R. tenuis, R. tenuis subsp. austro-brasiliensis and R. enmanuelis. Samples of these three taxonomic entities, besides R. junciformis and R. breviuscula (Dichromena), were analyzed in a comparative way using morphologic, cytogenetic and molecular tools. Despite of high morphological similarity between these taxa, R. tenuis was separated from R. tenuis subsp. austro-brasiliensis and R. enmanuelis according to chromosome numbers (2n = 4 and 2n = 18) and ISSR markers. The combined analysis of shape and size of achenes and stylopodium, number of spikelets, cytogenetic features and molecular markers suggest a clear proximity among Rhynchospora junciformis, R. tenuis subsp. austro-brasiliensis and R. enmanuelis, in relation to R. tenuis. These data indicate the need for a new taxonomic review of R. sect. Tenues, mainly to solve the status and nomenclatural situation of R. tenuis subsp. austro-brasiliensis and R. enmanuelis.

  • Morphological and genomic characterization of Rhynchospora tenuis complex (Cyperaceae) and its taxonomic implications Caracterização morfológica e genômica do complexo Rhynchospora tenuis (Cyperaceae) e suas implicações taxômicas
    2012
    Co-Authors: Vanessa Silva Michelan, Modesto Luceño, Rafael Trevisan, Carlos Roberto, Maximiano Da Silva, Rogério Fernandes De Souza, André Luís, Laforga Vanzela
    Abstract:

    of Rhynchospora sect. Tenues are morphologically very similar. Rhynchospora tenuis complex is the most problematic species complex in this group and it concentrates entities of difficult delimitation, as is the case of R. tenuis, R. tenuis subsp. austro-brasiliensis and R. enmanuelis. Samples of these three taxonomic entities, besides R. junciformis and R. breviuscula (Dichromena), were analyzed in a comparative way using morphologic, cytogenetic and molecular tools. Despite of high morphological similarity between these taxa, R. tenuis was separated from R. tenuis subsp. austro-brasiliensis and R. enmanuelis according to chromosome numbers (2n = 4 and 2n = 18) and ISSR markers. The combined analysis of shape and size of achenes and stylopodium, number of spikelets, cytogenetic features and molecular markers suggest a clear proximity among Rhynchospora junciformis, R. tenuis subsp. austro-brasiliensis and R. enmanuelis, in relation to R. tenuis. These data indicate the need for a new taxonomic review of R. sect. Tenues, mainly to solve the status

  • Multiple Locations of the rDNA Sites in Holocentric Chromosomes of Rhynchospora (Cyperaceae)
    Chromosome Research, 1998
    Co-Authors: André L. L. Vanzela, Modesto Luceño, Angeles Cuadrado, Nicolás Jouve, Marcelo Guerra
    Abstract:

    Several cytogenetic studies have shown that representatives of the family Cyperaceae have holocentric chromosomes. Despite their interesting chromosome morphology, the chromosome organization has not been studied. This paper reports on the number and distribution of 18S–5.8S–26S ribosomal RNA sites by fluorescence in situ hybridization in eight Brazilian species of Rhynchospora. The signal of the rDNA probe was always localized in the telomeric regions. A high degree of variation was observed in the number of labelled sites, ranging from 4–8 in karyotypes with 2n = 10 to 30 sites in a karyotype with 50 chromosomes. It is possible that the same mechanism involved in the multiplication of these regions in organisms with monocentric chromosomes also plays a role in the polymorphism observed in holocentric chromosomes of Rhynchospora. An interesting feature of most hybridization sites was their diffuse state observed through to early metaphase. The decondensed state probably reflects the later transcription of this region during the cell cycle.

  • agmatoploidy and symploidy in Rhynchospora cephalotes l vahl cyperaceae
    Cytologia, 1998
    Co-Authors: Modesto Luceño, A P Mendes, A L L Vanzela, M. V. Alves
    Abstract:

    In this paper we present the cytogenetic data of Rhynchospora cephalotes (L.) Vahl, in the section Cephalotae Kukenth. Chromosome numbers of R. cephalotes are assumed as 2n=17, 18 and 19. According to our data, it may be proposed that the disploids have evolved from processes of fusion and fission of the chromosomes of euploids.

  • Cytotaxonomic studies in Brazilian Rhynchospora (Cyperaceae), a genus exhibiting holocentric chromosomes
    Botany, 1998
    Co-Authors: Modesto Luceño, André Luís Laforga Vanzela, Marcelo Guerra
    Abstract:

    The genus Rhynchospora (Cyperaceae) is a widely distributed Brazilian group, with approximately 150 species. We have studied mitosis and (or) meiosis of 16 species of four sections (Dichromena, Longirostres, Polycephalae, and Pluriflorae). The results showed high frequencies of chromosome number multiples of x = 5, which is the probable basic number. Polyploidy, in contrast to agmatoploidy and (or) symploidy, seems to be the predominant cytogenetic mechanism in the evolution of the karyotype. Primary constrictions were not visible in the chromosomes, suggesting a holocentric condition, as observed in other genera of this family. Karyotype interspecific differences were useful in the cytotaxonomic analysis in three sections. Our data propose (i) the separation of Rhynchospora ciliata (Vahl.) Kukenth. from Rhynchospora nervosa (Vahl.) Bockeler (section Dichromena), (ii) the inclusion of Rhynchospora legrandii Kukenth. ex Barros as a subspecies of Rhynchospora corymbosa (L.) Britton (section Longirostres), a...