DOI: 10.5091/plecevo.172526

Authors: Murielle Simo-Droissart, Olivier Lachenaud, Moses Libalah, Bonaventure Sonké

Abstract: Background and aims – Riverine habitats along the Sanaga River in Cameroon were until recently little-explored by botanists, although they are facing increasing threats, notably from the construction of hydroelectric dams. Recent botanical inventories in the area have led to the discovery of several taxonomical novelties, including a new species of Phragmanthera (Loranthaceae) that is described here. Material and methods – This paper is based on field studies and examination of herbarium collections of the new species and its relatives. Classic practices of herbarium taxonomy have been applied. The conservation status of the new species is assessed following the IUCN Red List Categories and Criteria. Key results – Phragmanthera bidaultii sp. nov. is identified by its non-septate anthers (a unique character in the genus), by the patent to reflexed corolla lobes with the apex thickened into a conical appendage, and by its relatively narrow leaves, initially with sparse rufous barbellate hairs but soon becoming glabrescent on both sides. It has a very restricted distribution along the Sanaga River in Cameroon, where it grows in riparian forest, and it is assessed as Endangered (EN).

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DOI: 10.5091/plecevo.147801

Authors: Pablo Dupiol, Armel Chakocha, Marie-Louise Avana Tientcheu, Mohamed Mahamoud Charahabil, Cedric Mariac, Adeline Barnaud, Jérôme Duminil

Abstract: Background and aims – We developed a new set of nuclear microsatellite markers for Cola acuminata (Malvaceae), an important African food tree species commonly known as the kola nut. Probably originating from the tropical rainforests of the Congo Basin, C. acuminata is widely cultivated in the humid savannahs of the region where its nuts are sold throughout Central and West Africa for their stimulant properties. Nuclear microsatellite markers (SSRs) are well suited for assessing the genetic diversity and population structure of plant species due to their high variability. Material and methods – Leaf samples were collected from 84 C. acuminata cultivated individuals across three sites in Cameroon, two in the savannah zone, one in the forest zone. SSR markers were developed by sequencing genomic DNA from two individuals using an Illumina HiSeq platform. Genetic diversity was assessed based on 14 SSR markers genotyped in 84 individuals, and marker transferability to the closely related species Cola nitida was tested. Key results – Forty-eight new microsatellite loci were developed, of which 14 were polymorphic in C. acuminata. The results demonstrated a high level of genetic diversity with the presence of two to 33 alleles per locus (with an average of 14.14) across the three sites. The transferability of these markers was confirmed with 13 out of the 14 SSRs successfully amplifying in the closely related species, Cola nitida. Conclusion – These newly developed SSRs will be useful for assessing genetic diversity, genetic differentiation, and gene flow patterns of C. acuminata in the tropical forests of Central Africa. Preliminary results suggest genetic similarity between the two savannah sites. However, these two sites were significantly differentiated from the site in the forest zone. This suggests that the propagation material introduced in the savannah zone did not originate from the forest in southern Cameroon.

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DOI: 10.5091/plecevo.155517

Authors: Arthur Macedo, Marcelo Trovó, Tariq Stévart, João Farminhão

Abstract: Background and aims – Rhipidoglossum is the third most species-rich epiphytic orchid genus in continental Tropical Africa, containing at least 53 species. As part of an ongoing taxonomic revision, a new species endemic to the Western Rift Valley was identified. The novelty was previously confused with R. adoxum and R. globulosocalcaratum. Here, we aim to clarify the diagnostic traits and geographic distribution of these three species. Material and methods – We applied standard herbarium taxonomic practices to a geographically representative sampling of dry and spirit specimens identified as R. adoxum and R. globulosocalcaratum, and conducted a thorough review of regional floras and field photographs to compile all available information on the novelty. A synoptic table, distribution map, and the risk of extinction based on IUCN Red List conservation status accompany the description and illustration of this new species. Key results – Rhipidoglossum fischerianum sp. nov., R. globulosocalcaratum, and R. adoxum can be distinguished from each other based on stem size, leaf apex, perianth, and rostellum morphology. Rhipidoglossum fischerianum is endemic to the lower montane forests in the Western Rift, whereas R. globulosocalcaratum is restricted to the Guineo-Congolian forests, and newly recorded from Cameroon and Uganda. Rhipidoglossum adoxum is found in montane forests of Ethiopia, Kenya, and South Sudan. The new species is preliminarily assessed as Vulnerable (VU). The name R. globulosocalcaratum is here lectotypified. Conclusion – This new species increases the diversity of Rhipidoglossum in the Western Rift to 16 species, of which 10 are endemic or near-endemic to the region. It highlights the relevant role of ongoing taxonomic work and the preservation of the Western Rift forests, which harbour high levels of unique biodiversity.

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DOI: 10.5091/plecevo.133256

Authors: Bonaventure Sonké, Murielle Simo-Droissart, Ehoarn Bidault, Fernandez Ngoula, Xander M van der Burgt

Abstract: Background and aims – For some time now, the forests of the Sanaga basin in Cameroon have been threatened by the construction of numerous hydroelectric dams. In anticipation to this construction work, botanical surveys were carried out, resulting in the discovery of many species new to science. One of these certainly belongs to the genus Talbotiella in Leguminosae. Material and methods – This study is based on morphological observations on herbarium specimens, through detailed examination of 28 specimens of the new tree species as well as specimens of existing species of Talbotiella. Key results – Talbotiella couteronii is described and illustrated. The new species resembles Talbotiella batesii but has fewer leaflets, 5–10 pairs; an inflorescence usually with fewer flowers, 5–12; and flowers with longer pedicels, 10–20 mm long. Talbotiella couteronii is endemic to Cameroon, where it is restricted to the middle Sanaga basin in the Central Region and the Littoral Region. It occurs gregariously in periodically flooded riverine forests. Talbotiella couteronii is preliminarily assessed as Endangered following the IUCN Red List categories and criteria. The genus Talbotiella now consists of 10 species; of which six species are endemic to Cameroon. A comparative table summarizes the main vegetative characteristics of the 10 species. This treatment also includes an update of the description of T. bakossiensis.

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DOI: 10.5091/plecevo.102004

Authors: Alejandro Quintanar, Bonaventure Sonké, Murielle Simo-Droissart, Patricia Barberá, Moses Libalah, David J. Harris

Abstract: Background and aims – Specimens of a new tree species in the genus Drypetes (Putranjivaceae) distributed in Cameroon and eastern Nigeria, D. stevartii, were associated with D. verrucosa, another tree species endemic to Gabon, due to its warty fruits and to the overall morphological resemblances of both species. Material and methods – The present study is based on the study of 20 gatherings of D. verrucosa and 26 gatherings of D. stevartii. Morphological observations on herbarium specimens belonging to the new species and D. verrucosa were carried out in order to describe them. Key results – This treatment includes the detailed descriptions of these two species, the typification of their names, a comparative table summarizing their main morphological differences, an identification key, photographs of both, as well as information about their distribution, habitat, and phenology. Preliminary IUCN Red List assessments show that both D. verrucosa and D. stevartii are ‘Near Threatened’ species.

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DOI: 10.5091/plecevo.89701

Authors: Steven B. Janssens, Hermann Taedoumg, Steven Dessein

Abstract: Background and aims – The genus Impatiens is known for its enormous convergent phenotypic adaptation, with similar floral traits having independently evolved in distantly related lineages. The large functional convergence of Impatiens flowers causes a high degree of homoplasy for several phenotypic characters resulting in increased difficulties to distinguish between species with a similar morphology that are only distantly related, however. As a result, some species remain under the radar, as they are confused with other well-known species. This was the case for a new Impatiens species from the Tchabal Mbabo Mountains in Cameroon – Impatiens smetsiana – that was initially mistaken for the morphologically similar species I. erecticornis, an endemic from Central East Africa. Material and methods – A combined molecular-morphological approach was applied in which phylogenetics (ITS, ImpDEF1, and ImpDEF2), biogeography, and age estimation analyses were combined with morphological data on floral and vegetative structures. Key results – In this study, we demonstrate the close affinity of the newly collected material with a group of Equatorial West African species, including I. filicornu, I. nzabiana, I. oumina, and I. kamerunensis. The present finding represents a clear case of convergent evolution in which two distantly related taxa independently converged on practically the same flower morphology. Conclusion – Within Impatiens, several examples of floral homoplasy have been observed yet not in such a clear way. The convergent evolution of the flowers of I. smetsiana and I. erecticornis is undoubtedly closely correlated with an adaptation to a similar pollination syndrome.

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DOI: 10.5091/plecevo.2021.1823

Authors: Laura Azandi, Tariq Stévart, Bonaventure Sonké, Murielle Simo-Droissart, Tania D’haijère, Vincent Droissart

Abstract: Background and aims – A recent taxonomic and molecular study of the genus Cyrtorchis revealed three new species. Here, we describe one of these new species, endemic to the Cameroon Volcanic Line (CVL), and compare it to its closest relatives. Its conservation status is provided along with detailed information on its ecology and reproductive biology.Material and methods – A detailed examination of 21 herbarium specimens was performed using standard practices of herbarium taxonomy. The conservation status of the new species was assessed using the IUCN Red List Categories and Criteria. Furthermore, we investigated the reproductive biology of the new species in an easily accessible subpopulation in Cameroon and tested the hypothesis of hawkmoth pollination in the genus Cyrtorchis. Key results – The newly discovered species, here named C. okuensis, is restricted to the montane forest (1600 to 2500 m elevation) of the CVL and is currently assessed as Near Threatened (NT). Among angraecoid orchids in which hawkmoth pollination is recorded (~16 species), C. okuensis has the shortest nectar spur (19–40 mm). In situ observations revealed hawkmoths with short proboscis of the genus Hippotion (H. celerio, H. eson, and H. osiris) as the main pollinators. The rate of pollination and fruiting under natural conditions was low and among the 448 surveyed flowers only 38.8% (174/448 flowers) had their pollinia removed, 19% produced fruits (87/448 flowers), and 16% (70/448 flowers) set mature fruits. Conclusion – Cyrtorchis okuensis is clearly differentiated from C. submontana by its longer and wider floral bracts, longer anther caps, and wider triangular dorsal sepal.

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