Combining genetic and morphological markers is a powerful approach for species delimitation, much needed in tropical species complexes. Greenwayodendron (Annonaceae) is a widespread genus of trees ...distributed from West to East African rainforests. Two species and four infra-specific taxa are currently recognized. However, preliminary genetic studies and morphological observations suggested the occurrence of additional species, undescribed to date. We tested species delimitation within Greenwayodendron by combining morphological and population genetics data. First, a visual inspection of about a thousand specimens suggested the existence of seven morphogroups: four of them occur in Central Africa and overlap in Gabon while three others are allopatric, occurring respectively in West Africa, East Africa, and the islands of São Tomé and Príncipe. Their morphological differentiation was confirmed by analysis of 27 morphological characters coded from 233 herbarium specimens. Second, after genotyping 800 samples at eight nuclear microsatellites, Bayesian clustering analyses (STRUCTURE) identified four genetic clusters corresponding to the well-sampled morphogroups but failed to separate the three remaining morphogroups represented by few samples. However, we show that this is an inherent limit of the STRUCTURE algorithm, whereas factorial correspondence analysis (FCA) and pairwise FST and RST measures confirmed the genetic differentiation of all morphogroups. We considered that a clear genetic differentiation occurring between sympatric populations advocates for recognizing distinct species following the biological species concept. Our analyses highlight that the current taxonomic treatment of Greenwayodendron underestimates the total number of species. We identified two new species and support separation at the rank of species of two varieties (G. suaveolens subsp. suaveolens var. gabonica, G. suaveolens subsp. suaveolens var. suaveolens) and one subspecies (G. suaveolens subsp. usambaricum). The taxonomic status of specimens collected in São Tomé and Príncipe remains inconclusive, partly due to the limited fertile material available. Our study highlights the strength of combining morphological and population genetics data for discovering new taxa. Guidelines for using genetic clustering approaches in species delimitation are provided.
Background and aims
– Podostemaceae is a family of strictly aquatic plants found in rapids and waterfalls. Despite a recent treatment in the Flore du Gabon, the family remained poorly known, with no ...major studies including Gabonese collections, and almost no targeted inventories since 1966. We present the first large-scale inventory of this family in Gabon, targeting Podostemaceae throughout the country, providing new additions to the flora of Gabon and many new records of poorly known species.
Material and methods
– Fieldwork was conducted in Gabon between 2017 and 2021. The collected specimens were primarily preserved in ethanol with associated silica gel-preserved material and photographs. Material available at BR, BRLU, LBV, MO, P, WAG, and Z/ZT was examined. For each species, information on distribution and ecology is presented, as well as a distribution map in Gabon.
Key results
– The 500 newly collected specimens represent 91.4% of all known collections of Podostemaceae from Gabon. Three taxa are newly recorded for the country, including one genus (
Inversodicraea tenax
,
Ledermanniella schlechteri
, and
Saxicolella nana
). New distribution records are also presented for 13 little-known species. Four taxa are excluded from the Gabonese flora (the genus
Dicraeanthus
,
Inversodicraea ledermannii
,
Ledermanniella sanagaensis
, and
Macropodiella garrettii
). To date, 20 species belonging to five different genera are known to occur in Gabon. A new combination is proposed for
Ledermanniella nicolasii
, and
Inversodicraea tanzaniensis
is now considered as a synonym of
Inversodicraea tenax
.
Diarrhea is a condition that particularly affects children under five the age of years old in developing countries. The aim of this study was to evaluate the efficacy of medicinal extracts plants ...used in treatment and to characterize their inhibitory capacity in the growth of bacteria isolates in childhood diarrhea in the southeast region of Gabon. An ethnobotanical survey on the plants used in the treatment of diarrhea in southeastern Gabon was carried out and a phytochemical screening of the collected plants was performed. The antimicrobial activity of aqueous extracts was evaluated; 33 plant species were identified, representing 28 genera and 19 families. Bark (39.5%) was the most commonly used plant part, followed by powder formulations (28.9%). The preferred method of preparation and chewing (44.7%), together with drinking (36.8%), were the most prevalent modes of administration. Phytochemical screening showed a plethora of secondary metabolites (terpenoids, alkaloids and phenolic compounds), and a marked level of anti-diarrheal activity was found with Sida acuta and Santiria. ebo against Shigella spp. (16.22 ± 0.7 mm and 14.05 ± 1.4 mm) and Yersinia pestis (16.35 ± 0.5 mm and 15.51 ± 0.5 mm). The high diversity of secondary plant metabolites and their inhibitory ability against enteric pathogens would justify their use at the local level to treat diarrheal infections.
In this data paper, we present a specimen-based occurrence dataset compiled in the framework of the Conservation of Endemic Central African Trees (ECAT) project with the aim of producing global ...conservation assessments for the IUCN Red List. The project targets all tree species endemic or sub-endemic to the Central African region comprising the Democratic Republic of the Congo (DR Congo), Rwanda, and Burundi. The dataset contains 6361 plant collection records with occurrences of 8910 specimens from 337 taxa belonging to 153 genera in 52 families. Many of these tree taxa have restricted geographic ranges and are only known from a small number of herbarium specimens. As assessments for such taxa can be compromised by inadequate data, we transcribed and geo-referenced specimen label information to obtain a more accurate and complete locality dataset. All specimen data were manually cleaned and verified by botanical experts, resulting in improved data quality and consistency.
•An interpretation of criterion 1 of the High Conservation Value concept is proposed for plants.•A two-step procedure based on the IUCN Red List approach is described for rapidly identifying ...threatened taxa.•Automated assessments yielded the correct extinction risk category for 90 % of the taxa.•A total of 86 % of the 389 taxa analyzed are preliminary assessed as threatened.•A checklist of the 426 plant taxa endemic to Gabon is provided.
The High Conservation Value (HCV) concept, developed by the Forest Stewardship Council to promote sustainable forest management, is widely employed for certification of forestry and agriculture concessions, and has been adopted by many logging and palm oil companies. HCV criterion 1, which deals with “endemic, and rare, threatened or endangered species”, is rarely used in certification, mainly because lists of these species are incomplete, especially for plants, and performing threat assessments is time-consuming. The IUCN Red List Categories are often suggested as a suitable basis to define threatened taxa for the application of HCV1, but this requires the rapid and efficient assessment of large numbers of species. Using the plants endemic to Gabon as a case study, we propose a rapid, two-step procedure to identify HCV1 species. First, based on 3,298 verified and geo-referenced herbarium records, we used GIS layers and an automated computational workflow in the R environment to identify potentially threatened species using an approach aligned with IUCN Red List criteria A, B, and D. Ninety percent of the automated assessments correctly indicated the risk of extinction; errors involved incorrect assessments of species whose habitat is in reality not threatened, or occurred during the calculation of the number of locations (sensu IUCN) when a single threat impacts large areas. In a second step designed to correct these issues and comply with the Red List guidelines, we performed species-by-species verification of the automated assessments, taking into account the ecology and habitat of each species and the nature of the threats it faces. Of the 389 endemic taxa analyzed, 86 % were identified as threatened (83 CR, 171 EN, and 80 VU); of these, only 35 % are recorded from at least one National Park, but most are found in logging/oil palm (72 %) or mining (55 %) concessions, underscoring the need to improve the application of the HCV concept. To strengthen the use of HVC subcriterion 1.2 (rare, threatened or endangered species), we propose an explicit method for identifying rare species based on a quantitative threshold of the Extent of Occurrence (20,000 km²), and we examine the concept of endemicity with respect to the application of HVC subcriterion 1.3 (endemic species). The proposed methodology addresses an urgent need to develop a national interpretation of the HCV concept in Gabon, adopted as a national standard for logging concessions, and offers an efficient, reliable approach for the application of HVC1 elsewhere in Central Africa.
Background: Tropical forests are renowned for hosting a remarkable diversity, but the estimation of their species richness depends on the species concept used for their delimitation. Hence, species ...richness can be underestimated by the occurrence of cryptic species or overestimated by taxonomical oversplitting. Phylogenetic approaches are increasingly used to help decipher species delimitation. However, reciprocal monophyly at gene trees requires that the number of generations since speciation largely exceeds the effective population sizes of the sister species. Alternatively, population genetics methods allow to assess reproductive isolation, which is at the basis of the biological species concept. Using the latter species concept, we relied on large-scale genotyping using nuclear microsatellite markers to evaluate species delimitation in several African tree taxa. To this end, we considered that distinct species can be recognized when well differentiated genetic clusters occur in sympatry. Results: ( i ) We found no case of oversplitting: even when phenotypically very similar, species distinguished by taxonomists formed distinct genetic clusters, although hybridization was occasionally detected. ( ii ) By contrast, in nearly half of the taxonomical species investigated, we found several sympatric genetic clusters, indicating that cryptic species are not uncommon. ( iii ) Interestingly, a re-examination of morphological traits associated to each genetic cluster can reveal diagnostic characters, so that taxonomy can greatly benefit from population genetics approaches to resolve species complexes. ( iv ) Finally, we found that markers from the chloroplast genome were not always reliable to distinguish closely related species, limiting the usefulness of plastid- based DNA barcodes. Significance: According to our results the number of African tropical tree species might in reality be underestimated by a two-fold factor due to (near) cryptic species.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Ikabanga, D.U., K.G. Koffi, J.M. Onana, B. M'Batchi, O.J. Hardy & T. Stévart (2019). Taxonomic revision of Santiria (Burseraceae) in Tropical Africa. Candollea 74: 115–130. In French, English and ...French abstracts. DOI: http://dx.doi.org/10.15553/c2019v742a1 In Tropical Africa, the genus Santiria Blume (Burseraceae) was considered as having one species, Santiria trimera (Oliv.) H.J. Lam ex Aubrév. The recent studies combining morphometric and molecular analysis revealed four isolated genetic groups that can be distinguished with clear morphological features. Following this study, a taxonomic revision of Santiria is conducted in tropical Africa, including the islands of the Gulf of Guinea. Four species are recognized: in addition to Santiria trimera, taxa previously described as Santiria balsamifera Oliv., Santiria ebo (Pierre) H.J. Lam and Santiria obovata (Pierre) H.J. Lam are re-established. Morphological distinctive traits that differentiate the four species are abundance of the elemi, presence/absence of lenticels on the twigs, pubescence of the inflorescence, and immature fruit color. A taxonomic key is provided. Three neotypes and two lectotypes are designated (including synonyms). Each species is described, affinities with other taxa, uses, field pictures and a preliminary conservation status according to the IUCN Categories and Criteria are provided.
Introduction: Roselle is a wet rot in Gabon caused by Phoma sabdariffae Sacc., a deuteromycete fungus of the family Phomaceae. The chemical control used for its eradication has had many limitations, ...including the appearance of fungal resistance and the persistence of chemoactive substances. Objective: The present study was initiated to test an alternative control solution, by the use of a toxic plant, Tephrosia vogelii. Methods: For this purpose, this plant was macerated, and the solutions transferred to PDA solid culture media, to constitute 4 treatments: T5 (5%), T10 (10%), T15 (15%) and T20 (20%). Fungal spores were cultured in the center of petri dishes, and mycelial growths measured every 2 days for 10 days. Results: The results revealed that all the modified treatments in solution of Tephrosia vogelii reduced the mycelial growth of Phoma sabdariffae. The most pronounced reductions were produced by the T15 and T20 treatments, with the respective inhibition rates of 81% and 100% at the 10th day of incubation. Conclusion: The use of concentrated extracts of Tephrosia vogelii is therefore possible in the biological control of roselle rot in Gabon.
Le nectar de canne à sucre (Saccharum officinarum L.) est utilisé au Gabon non seulement pour la fabrication du sucre industriel, mais également pour la synthèse traditionnelle de vins locaux appelés ...‘‘Musungu’’ ou ‘‘Malamba’’. Ces synthèses alcooliques nécessitent l’emploi de nombreux adjuvants dont le rôle exact reste mal défini. Le présent travail a été initié pour étudier l’un d’eux, le bois amer (Garcinia kola) utilisé dans diverses synthèses alcooliques. La méthodologie a consisté à analyser l’évolution de certaines qualités physicochimiques et biochimiques de 1 l des nectars de canne à sucre seuls (témoin), associés à la lie d’anciens vins de canne (Li), au bois amer (Gk) ou à ces 2 amendements (LG), avant et après 4 semaines de fermentation. Les résultats obtenus ont révélé la baisse de l’acidité, de la densité et des sucres totaux dans tous les traitements essais, contrairement aux témoins, après les 28 jours d’incubation. Tous les traitements (essais et témoins) ont en revanche produit des alcools de fortes teneurs comprises entre 7,4 °GL et 9,9 °GL. Mais les vins des traitements témoins quoique très alcoolisés ont tous été jugés aigres et de très mauvaise qualité gustative. Le bois amer ne paraît donc pas intervenir dans les processus de fermentation alcoolique, mais dans la constitution des qualités organoleptiques, en empêchant la prolifération des germes lactiques. Ainsi, dans la perspective d’optimiser la qualité du vin, identifier les germes participants à la fermentation du nectar de canne, sous l’influence de Garcia kola semble être nécessaire.Mots clés : Nectar, Levures, Adjuvants, Alcool, Qualité organoleptique.
English Title: Effect of Garcinia kola (Clusiaceae) in the fermentation processes of sugar cane wine (Saccharum officinarum ; Poaceae) in Gabon
Sugarcane nectar (Saccharum officinarum L.) is used in Gabon not only for the production of industrial sugar, but also for the traditional synthesis of local wines called ''Musungu'' or ''Malamba''. These alcoholic syntheses require the use of many adjuvants whose exact role remains poorly defined. The present work was undertaken to study one of them, the bitter wood (Garcinia kola) used in various alcoholic syntheses. The methodology consisted of analyzing the evolution of certain of physicochemical and biochemical qualities of 1 l of sugar cane nectars alone (control), associated with the lees of old cane wines (Li), bitter wood (Gk) or 2 amendments (LG), before and after 4 weeks of fermentation. The results obtained revealed the decrease of the acidity, the density and the total sugars in all the treatments tests, contrary to the controls, after the 28 days of incubation. On the other hand, all the treatments (tests and controls) produced alcohols with high contents of between 7.4 °GL and 9.9 °GL. But the wines of the control treatments, although very alcoholic, have all been judged as sour and of very poor taste quality. Bitter wood therefore does not appear to be involved in the processes of alcoholic fermentation, but in the constitution of organoleptic qualities, by preventing the proliferation of lactic acid bacteria. Thus, in order to optimize the quality of the wine, identifying the germs involved in the fermentation of cane nectar, under the influence of Garcia kola seems to be necessary.Keywords: Nectar, Yeasts, Additive, Alcohol, Organoleptic quality.
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