Biology subjects

Magassouba, S.

Publications and source records attributed to Magassouba, S..

7 recordsLinked to original sources

bioRxiv2025

Keetia tinka sp. nov. & K. kounounkan sp.nov. (Rubiaceae - Vanguerieae) new threatened forest climbers and shrubs of sandstone plateau of the Republic of Guinea.

Two new species of Keetia are described from recent botanical collections for conservation management made in surviving submontane forest areas of the sandstone plateau areas of the Republic of Guinea. Keetia kounounkan Cheek & Simbiano is a shrub of the Kounounkan Plateau towards the border of Sierra Leone, so far with a single location in gallery forest. K. tinka Cheek & Simbiano is an evergreen rainforest climber of the main part of the Fouta Djalon Highlands with two locations both in degraded forest. Both species are described, illustrated and provisionally assessed for their conservation status, the first as Critically Endangered, the second as Endangered.

plant biology↗

bioRxiv2025

Traditional uses, population, threats and conservation of the bansouman or gingerbread plum Neocarya macrophylla (Chrysobalanaceae) in Republic of Guinea (West Africa)

The flora of the Republic of Guinea (West Africa) includes nearly 4000 vascular plants species, of which c. 10% have been documented to have local socio-economic uses. These socio-economic plants provide among others, foods, medicines, materials and a source of income for the people of Guinea. One example is the bansouman or gingerbread plum, Neocarya macrophylla (Chrysobalanaceae) which is locally valued for its large, delicious seeds (nuts), edible fruit flesh, and medicinal bark (among other medicinal parts). Through a field survey of 17 local communities adjacent to Neocarya populations and the Neocarya populations themselves (780 mature individuals measured), in seven of the ten Guinean prefectures from which the species is recorded, this study documents (1) the local names, harvesting methods, uses and seed sale prices at different points in the value chain, partitions the species by habitat, records perceived threats to trees, key elements of the population structure and relative frequency of Neocarya macrophylla in Guinea, (2) map and re assesses its global conservation status as Near Threatened using the 2012 IUCN Red List categories and criteria, and (3) construct a species conservation action plan. Analysis of our survey data suggests that the largest number of mature trees (75% of the total) is in the three northern prefectures (Gaoual, Koundara, Pita) at the western foot of the Fouta massif whence seeds are exported internationally. Trees mainly occurred in shrub savannah (45% of mature individuals), with lower numbers in three other habitats. Human set bush fires appear to be the most ubiquitous threat (55%) in Guinea, but sand quarrying (18%), agricultural conversion and debarking are also key threats. Natural regeneration levels seem low compared with data from Niger with juveniles (<1 m tall) less than 10 % of the number of mature, fruiting trees (> 11 cm circumference) recorded. This is the first study focused on Neocarya macrophylla in the Republic of Guinea. In contrast the species has been the subject of numerous other papers elsewhere in its range, and we document 14 studies from Niger alone in the last 15 years. While the species is well known as an important Indigenous Fruit Tree with multiple uses in some countries, it is currently not among the top 10 such species listed for Guinea. Compared with Nigeria where numerous other uses including industrial are derived from the species, Neocarya macrophylla appears under utilised in Guinea. We suggest that studies of the chemistry and nutritional value of the seeds of Guinean Neocarya are made, since there are indications that these differ between Guinea and e.g. Niger. Follow up studies to map tree distribution in Guinea in more detail, quantify tree density, fruit yield per tree and per Ha, and duration between germination and fruiting are advised. Field trials to select elite individuals are recommended. Development of a machine to extract seeds from the endocarp (decortication) is a priority as this is the major factor limiting wild harvesting and availability of seed for human consumption.

plant biology↗

bioRxiv2024

Virectaria stellata (Sabiceeae Rubiaceae), a new sandstone cliff species from the Republic of Guinea with stellate hairs recorded for the first time in the Rubiaceae

Virectaria is a morphologically isolated genus of tropical African herbs or subshrubs, occurring from Senegal to Tanzania. Virectaria stellata, a new species from Guinea, is published. It is a perennial herb, with stems becoming creeping and rooting, to 60 cm long. Virectaria stellata has stellate hairs, recorded here for the first time in the family Rubiaceae. We hypothesize that the stellate hairs of this species result from horizontal gene flow from an Acanthaceae, most likely Barleria, due to their common and perhaps unique microstructure. Virectaria stellata is found in Forecariah and Kindia Prefectures in the Republic of Guinea. The species occurs in fissures in vertical sandstone rock at altitudes of 450 to 910 m, in sun or half-shade. An overview of sandstone endemic plant species in the vicinity of the new Virectaria is provided. No threats have been observed, therefore, Virectaria stellata is provisionally assessed here as Least Concern (LC).

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↗

bioRxiv2022

The generic status of Anacolosa (Olacaceae) in Africa with A. deniseae a new species to science of Endangered submontane forest liana from Simandou, Republic of Guinea.

Anacolosa deniseae Cheek (Olacaceae) a submontane gallery forest canopy liana is described as a new species to science and assessed as Endangered using the IUCN 2012 standard due to threats of habitat destruction connected with mining. The roots smell of benzaldehyde when scraped, and the plant reproduces from root suckers. The species is restricted globally to two locations in the Loma-Man Highlands of the Republic of Guinea, all records but one being in the Pic de Fon Foret Classe of the Simandou Range. We show that this and the only other continental African species ascribed to the genus Anacolosa, A. uncifera of DRC, Gabon & C.A.R., differ in so many architectural, floral and vegetative characters from the remaining species of the genus, which occur from Madagascar to the Western Pacific, including the type A. frutescens (S.E. Asia and Indo-China), that they clearly represent a separate genus. The African genus represented by these two species is unique within the Olacaceae (excluding Erythropalaceae) in being a climber (vs. shrubs or trees in Anacolosa sensu stricto). Climbing in the two African species is achieved by perennial hook-like structures formed by a combination of five separate traits each of which is unknown elsewhere in the Olacaceae. We formally delimit and describe this new genus, discussing its characteristics, but in the absence of molecular phylogenetic data, refrain from naming it.

plant biology↗

bioRxiv2021

Taxonomic Monograph of Saxicolella (Podostemaceae), African waterfall plants highly threatened by Hydro-Electric projects, with five new species.

The genus Saxicolella Engl. (Podostemaceae) are African rheophytes, restricted to rapids and waterfalls as are all members of the family. Previously, Saxicolella sensu lato was shown to be polyphyletic with two separate clades in the molecular phylogenetic study of Koi et al. (2012). The name Pohliella Engl. was recently resurrected for one clade that is sister to the American genera Ceratolacis (Tul.)Wedd., Podostemum Michx. and all Old World Podostemoideae (podostemoids) (Cheek 2020). Pohliella has distichous phyllotaxy, bilocular ovaries, filiform roots with paired holdfasts, and rootcaps. The second clade, Saxicolella sensu stricto, including the type of the generic name, has spiral phyllotaxy, unilocular ovaries, ribbon-like or crustose roots that lack both holdfasts and rootcaps. Saxicolella sensu stricto, sampled from the type species, S. nana Engl. of Cameroon, is embedded within and near the base of the major clade of African podostemoids and is sister to all other African genera apart from Inversodicraea R.E.Fr. and Monandriella Engl. Recently reduced to three species in Cameroon and S.E. Nigeria by the resurrection of Pohliella (3 - 4 species in Ghana and Nigeria-Cameroon), Saxicolella sensu stricto is expanded to eight species in this monograph by description of five new taxa. Saxicolella futa Cheek and S. deniseae Cheek are newly described from Guinea, S. ijim Cheek from Cameroon, the informally named S. sp. A from Gabon, and S. angola Cheek from Angola. The known geographic range of the genus is thus expanded c. 2,500 km westwards to Guinea from eastern Nigeria and c.1,500 km southeastwards from near Yaounde to Cuanza do Sul, Angola. The greatest concentration of species occurs in the Cross-Sanaga interval of western Cameroon and eastern Nigeria, with three species. Cameroon (3 species) followed by Nigeria and Guinea (2 species each) are the countries with highest species diversity. The genus can be expected to be found in Sierra Leone, Liberia, Ivory Coast and Congo Republic. A classification is proposed grouping the species into three subgenera (Saxicolella, Butumia (G.Taylor) Cheek comb. et. stat. nov. and Kinkonia Cheek subgen. nov.) based on root morphology and shoot position and morphology. The discovery, morphology, circumscription, distribution, and ecology of Saxicolella is reviewed, an identification key to the species is presented, together with descriptions, synonymy, links to illustrations, and extinction risk assessments for each of the eight species now recognised. All of the species are provisionally assessed as either Endangered or Critically Endangered using the IUCN 2012 standard, making this genus among the most threatened of its size globally. The major threats, above all, are hydro-electric projects. Saxicolella deniseae may already be globally extinct, and two of the four known locations of S. angola appear lost, S. sp. A of Gabon is threatened at at least one of its three locations, while Saxicolella futa is threatened at all three locations, all due to incipient or active hydro-electric projects. Contamination of watercourses by increased turbidity from silt-load due anthropic changes and by eutrophication from pollution are also threats for the majority of the species.

plant biology↗

bioRxiv2020

An analysis of Species Conservation Action Plans in Guinea

To achieve conservation success, we need to support the recovery of threatened species. Yet, <5% of plant species listed as threatened on the IUCN Red List have Species Conservation Action Plans (CAPs). If we are to move from a Red List to a Green List for threatened plant species, CAPs need to be devised and implemented. Guinea is one of the most botanically diverse countries in West Africa. Recent research found that nearly 4000 vascular plants occur in Guinea, a 30% increase from previous estimates. 273 of these plant species are now assessed as threatened with global extinction. There is increasing pressure on the environment from the extractive industry and a growing population. In parallel with implementation of an Important Plant Area programme in Guinea, CAPs were developed for 20 threatened plant species. These plans elaborate conservation efforts needed first to safeguard threatened species both in situ and ex situ and then to support their recovery. We document the approach used to assemble the Species Conservation Action Plans, and we discuss the importance of having up to date field information, IUCN Red List assessments, and use of a collaborative approach. The need for these plans is increasingly important with recent calculations suggesting a third of African plants are threatened with extinction. This paper outlines initial detailed plant conservation planning in Guinea and offers a template for conservation practitioners in other tropical African countries to follow.

ecology↗