Department of Biological Sciences

Permanent URI for this collectionhttps://dspace.njala.edu.sl/handle/20.500.144402/136

Browse

Filters

2016 - 20183

Advanced Search

Filter by

Settings

Author: search.filters.author.Cheek, MartinHas files: Yes

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Discovering Karima (Euphorbiaceae), a New Crotonoid Genus from West Tropical Africa Long Hidden within Croton
    (Public Library of Science, 2016-04-06) Cheek, Martin
    Croton scarciesii (Euphorbiaceae-Crotonoideae), a rheophytic shrub from West Africa, is shown to have been misplaced in Croton for 120 years, having none of the diagnostic characters of that genus, but rather a set of characters present in no known genus of the family. Pollen analysis shows that the new genus Karima belongs to the inaperturate crotonoid group. Analysis of a concatenated molecular dataset combining trnL-F and rbcL sequences positioned Karima as sister to Neoholstia from south eastern tropical Africa in a well-supported clade comprised of genera of subtribes Grosserineae and Neoboutonieae of the inaperturate crotonoid genera. Several morphological characters support the relationship of Karima with Neoholstia, yet separation is merited by numerous characters usually associated with generic rank in Euphorbiaceae. Quantitative ecological data and a conservation assessment supplement illustrations and descriptions of the taxon.
  • Thumbnail Image
    Item
    Ledermanniella yiben sp. nov. (Podostemaceae), Critically Endangered at the proposed Yiben Reservoir, Sierra Leone
    (Springer Science+Business Media, 2017-06-01) Cheek, Martin
    In the course of a botanical baseline survey for the proposed Yiben Hydroelectric Dam on the Seli River, upriver of the Bumbuna Dam, Sierra Leone, in April 2016, the second and third authors encountered a species of Podostemaceae, van der Burgt 1992. The plants were scattered densely along the gneissic rock bed of the river, then at its seasonal lowest level, largely dry, and with only a small channel of moving water, it being the end of the dry season. The plants were 20 – 50 cm diameter, spaced at distances of up to 50 cm apart from each other, with bare gneissic base rock in between, and appear restricted to the vicinity of a single set of rapids.
  • Thumbnail Image
    Item
    Lebbiea (Podostemaceae-Podostemoideae), a new, nearly extinct genus with foliose tepals, in Sierra Leone
    (Public Library of Science, 2018-10-05) Cheek, Martin
    Lebbiea grandiflora (Podostemaceae), a rheophytic herb from the Sewa River rapids in Sierra Leone, is described as a new species. It is the first new African genus of Podostemaceae published for 30 years. First collected in May 2017, the species is assessed as Critically Endangered using the IUCN 2012 standard. It is on the edge of extinction with a small population at a single site threatened by deposition of gravel and sand from alluvial gold and diamond mining upstream, and a planned hydro-electric dam. The new genus is unique in Podostemaceae in a) its highly developed and robust style-stigma structure in which the bases of the two style-stigmas unite to form a bifurcate funneliform-cylindrical structure, with a reflexed, blade-like apex that extends half-way around the perimeter of the ovary-fruit towards the base of the ovary-fruit, b) a specialised andropodium, with robust, self-supporting capacity, having differentiated thickened central, and angled, thinner marginal areas (in other Podostemaceae the andropodial structures are undifferentiated), c) the pillar-like haptera which completely elevate the crustose root above the substrate. Lebbiea is placed in Podostemoideae, necessitating amplification of the delimitation of that subfamily in which it is additionally unique in having the foliose tepals characteristic of the basal subfamilies Weddellinoideae and Tristichoideae.