Biology subjects

Tchiengue, B.

Publications and source records attributed to Tchiengue, B..

4 recordsLinked to original sources

bioRxiv2023

The endemic plant species of Ebo Forest, Littoral Region, Cameroon with a new Critically Endangered cloud forest shrub, Memecylon ebo (Melastomataceae-Olisbeoideae)

We emphasise the urgent need to conserve the Ebo forest (Littoral Region, Cameroon), which holds 10 strict endemic plant species and 15 near endemics for a total of 25, a very high number far exceeding the threshold for its recent status as an Important Plant Area (IPA). We describe a further strict endemic species from the Ebo Forest, Memecylon ebo sp. nov. (Melastomataceae-Olisbeoideae) placed in sect. Afzeliana due to its ellipsoid blue-green fruits. The yellow petals and jade green anther-connectives of M. ebo are unique in the genus Memecylon as a whole, among its >400 species ranging overall from Africa to the western Pacific. Memecylon ebo is assessed as Critically Endangered (CR) using the 2012 IUCN standard due to the small range size and the extremely high and ongoing threats of logging at Ebo, and also due to subsequent threats of potential oil palm plantation and mining projects. With the addition of Memecylon ebo, the tally of Critically Endangered plant species recorded from Ebo forest is now the highest of any IPA in Cameroon, equalling that of, Ngovayang with 24 CR species.

plant biology↗

bioRxiv2023

Gymnosiphon fonensis (Burmanniaceae) a new Critically Endangered species from Simandou, Republic of Guinea, W. Africa.

A new species of Gymnosiphon Blume (Burmanniaceae), G.fonensis Cheek is formally described from the Foret Classee de Pic de Fon, Simandou Range, Guinee-Forestiere, Republic of Guinea (Guinee-Conakry) in West Africa. The new species was formerly confused with and resembles G. bekensis Letouzey of central Africa in the broad flat outer tepal lobes, perianth tube >10 mm long, and (sub)sessile flower. It differs e.g. in that the length of the corolla tube, (13-)14-18 mm, exceeds the corolla diameter (10-11 mm) (vs length of the corolla tube (12 mm) < the corolla diameter (12-15 mm)), the anthers inserted c. 4 mm deep in the corolla tube (vs inserted at the corolla mouth) and the rhizome lacks scale-leaves (vs scale leaves present). Gymnosiphon fonensis is the first known species of its genus and family in which secondary pollen presentation has been recorded. The species is known from five sites, all with threats, in a single threat-based location, accordingly it is assessed as Critically Endangered (CR B1ab(iii)) using the IUCN 2012 standard, making it the most threatened species of Gymnosiphon in continental Africa. The new species is illustrated by colour photos and line-drawings and is mapped. An identification key is provided to the ten species of the genus now known from Africa-Madagascar.

plant biology↗

bioRxiv2020

Taxonomic revision of the threatened African genus Pseudohydrosme Engl. (Araceae), with P. ebo, a new, Critically Endangered species from Ebo, Cameroon.

This is the first revision in nearly 130 years of the African genus Pseudohydrosme, formerly considered endemic to Gabon. Sister to Anchomanes, Pseudohydrosme is distinct from Anchomanes because of its 2-3-locular ovary (not unilocular), peduncle concealed by cataphylls at anthesis and far shorter than the spathe (not exposed, far exceeding the spathe), stipitate fruits and viviparous (vegetatively apomictic) roots (not sessile, roots non-viviparous). Three species, one new to science, are recognised, in two sections. Although doubt has previously been cast on the value of recognising Pseudohydrosme buettneri, of Gabon, it is here accepted and maintained as a distinct species in the monotypic section, Zyganthera. However, it is considered to be probably globally extinct. Pseudohydrosme gabunensis, type species of the genus, also Gabonese, is maintained in Sect. Pseudohydrosme together with Pseudohydrosme ebo sp.nov. of the Ebo Forest, Littoral, Cameroon, the first addition to the genus since the nineteenth century, and which extends the range of the genus 450 km north from Gabon, into the Cross-Sanaga biogeographic area. The discovery of Pseudohydrosme ebo resulted from a series of surveys for conservation management in Cameroon, and triggered this paper. All three species of Pseudohydrosme are morphologically characterised, their habitat and biogeography discussed, and their extinction risks are respectively assessed as Critically Endangered (Possibly Extinct), Endangered and Critically Endangered using the IUCN standard. Clearance of forest habitat for logging, followed by agriculture or urbanisation are major threats. One of the species may occur in a formally protected areas and is also cultivated widely but infrequently in Europe and the USA for its spectacular inflorescences.

plant biology↗

bioRxiv2019

Notes on the endemic cloud forest plants of the Cameroon Highlands and the new, Endangered, Tricalysia elmar (Coffeeae-Rubiaceae)

Background and aimsThis paper reports a further discovery in the context of a long-term botanical survey in the Cross River-Sanaga interval of west-central Africa, focussing on species discovery and conservation.\n\nMethodsNormal practices of herbarium taxonomy have been applied to study the material collected. The relevant collections are stored in the Herbarium of the Royal Botanic Gardens, Kew, London and at the Institute of Research in Agronomic Development - National Herbarium of Cameroon.\n\nKey resultsNew species to science continue to be discovered from the cloud (submontane) forests of the Cameroon Highlands in Cameroon. Most of these species are rare, highly localised, and threatened by habitat destruction. These discoveries increase the justification for improved conservation management of surviving habitat. Tricalysia elmar Cheek (Coffeeae-Rubiaceae) is described as an additional species new to science and is compared with similar species of the genus. Restricted so far to four locations, Mt Kupe, Bali Ngemba, Lebialem and Nta Ali, its conservation status is assessed as Endangered (EN B1+2ab(iii)) according to the 2012 criteria of IUCN.

plant biology↗