Vivipary, a rare phenomenon in Afrotropical Melastomataceae: first report in Amphiblemma ciliatum (Sonerileae)

Background and aims – Within angiosperms, vivipary has been reported in less than 0.1% of all species. We herein report the first occurrence of vivipary in an Afrotropical Melastomataceae and discuss its phylogenetic position, habit, habitat, and fruit attributes. Material and methods – Observational data were gathered from a field expedition to Gabon, and from herbarium specimens from BR, BRLU, P, and WAG. A phylogeny was generated to map all the eight species exhibiting vivipary in Melastomataceae. Key results – Amphiblemma ciliatum is currently the only known melastome species in the Afrotropics exhibiting vivipary. It is likely that its angular capsules depend on rainwater for seed dispersal. Conclusion – The combination of a herbaceous habit and angular fruits with the occurrence on shaded humid tropical rainforest floor during periods of incessant rainfall and high humidity might be responsible for vivipary in most Melastomataceae

Novitates Gabonenses 93: a fresh look at Podostemaceae in Gabon following recent inventories, with a new combination for Ledermanniella nicolasii

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

New and little-known species of Englerodendron (Leguminosae-Detarioideae) from Central Africa, with a revised key to the genus

Background and aims – The genus Englerodendron (Leguminosae-Detarioideae) has recently been enlarged to include Isomacrolobium and Pseudomacrolobium, and currently includes 18 tropical African species. The recent discovery of a new species in Gabon has led us to re-evaluate the delimitation of several taxa in the genus. Material and methods – This paper is based on field work by the authors in Gabon, and on a study of herbarium material from BR, BRLU, K, LBV, MO, P, and WAG; normal practices of herbarium taxonomy have been applied. Results – Englerodendron nguemae is described and illustrated as a new species, endemic to Gabon. It is remarkable for the variation in its leaves, which may be 2-jugate, 1-jugate, or unifoliolate on the same plant. The species is most similar to E. brachyrhachis, but the latter has uniformly 2-jugate leaves; E. nguemae also differs in its longer and more broadly winged leaf rachis (if present) that is convex (not flat) above, its stamen filaments pubescent at the base, and its glabrous style. Several collections from the Democratic Republic of the Congo, previously associated with E. obanense, are considered here to represent two different taxa. One of them, E. macranthum (a new combination and name at new rank based on Macrolobium isopetalum var. macranthum, which is raised to species status), is endemic to the Mayombe range and differs from E. obanense by its inflorescences branched from the base or nearly so, and its shorter 1-seeded pods. The other taxon, still imperfectly known and here treated as Englerodendron sp. A, is endemic to the Kivu region; it differs from E. obanense by its large foliaceous stipules and from E. conchyliophorum by the lack of a basal auricle on the stipules. In addition, the first records of E. leptorrhachis from Equatorial Guinea, and of E. conchyliophorum from the Republic of the Congo, are documented, and a revised key to the now 21 species (one undescribed) of Englerodendron is presented.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Taxonomic revision of the genus Massularia (Rubiaceae, Gardenieae), with a new species from Central Africa

International audienceBased on a careful examination of more than 700 herbarium specimens and field investigation, a comprehensive revision of the genus Massularia is given. Massularia stevartiana, a new species from Central African Republic, Cameroon and Gabon is described and illustrated. The novelty is distinguished from M. acuminata, the only other species previously recognized in the genus, by its smaller leaves and flowers. For the two species recognized we provide a morphological description, distribution, habitat, phenology and IUCN conservation status assessment. Distribution maps and a dichotomous key are also provide

Anatomie florale de <i>Pseudartabotrys</i> Pellegrin (Annonaceae), un genre monospécifique endémique du Gabon

L’anatomie florale du genre gabonais monotypique Pseudartabotrys Pellegrin a été étudiée, afin de parvenir à une meilleure compréhension de l’apparition de la pseudosyncarpie et du contexte morphologique associé. La vascularisation du réceptacle est médiocrement avancée, avec un système cortical partiel, beaucoup moins étendu que celui des Annona L. L’histologie de l’anthère est complexe, avec un épais sclérenchyme d’origine hypodermique sur la face abaxiale, rappelant celui précédemment vu chez Uvaria scabrida Oliver, dont le fruit évoque d’assez près un pseudosyncarpe. L’anthotaxie du gynécée, les carpelles 1(2)-ovulés et le compitum externe formé par un capuchon muqueux préparent le fruit pseudosyncarpique réalisé à maturité. Les vascularisations de l’androcée et du gynécée sont libres et à la fois trimères et pentamères, selon la condition probablement ancestrale dans les Magnoliales. Un type de corps nourriciers, nouveau pour les Annonaceae, est reconnu et brièvement décrit à la base concave adaxiale des pétales internes, il est d’origine épidermique, avec une trame lipidique alvéolaire et sans lien direct avec la nervation. Nous soulignons l’intérêt d’une approche classique de taxons endémiques, parfois menacés, qui se révèlent souvent cruciaux dans la compréhension d’une phylogénie, tant par les résultats primaires obtenus, que par les recherches de terrain et les expériences futures qu’ils inspirent, en regard de taxons plus largement répartis.Floral anatomy of the monotypic Gabonese genus Pseudartabotrys Pellegrin was studied, in order to get a better understanding of the origin of pseudosyncarpy and its morphological context. Receptacle vasculature is moderately advanced with a partial perianth cortical vascular system, however much less developed than that of Annona L. Anther histology is complex, with a thick hypodermal sclerenchyma on the abaxial side, reminiscent of that previously recognized in Uvaria scabrida Oliver, whose fruit resembles a pseudosyncarp. Gynoecial anthotaxy, 1 (2)-ovulate carpels and an outer compitum foreshadow the pseudosyncarpous fruit. Androecial and gynoecial vasculatures are free and both trimerous and pentamerous, following the likely basal condition in Magnoliales. A new kind of food body for the Annonaceae, found at the adaxial concave base of the inner petals, epidermal in origin with a lipidic spongy frame and showing no direct connection with venation, is briefly described. We emphasized the significance of classical approaches in the study of endemic and possibly endangered taxa, which are often revealed to be critical in the understanding of biological evolution, both by the primary data obtained and by the field and experimental researches they further suggest, in comparison with more widely distributed taxa.</p

Polystachya orophila (Orchidaceae, Polystachynae), a new species from tropical West Africa, and clarification on the nomenclature and taxonomy of P. microbambusa

Polystachya orophila, a new species of Orchidaceae, is described based on specimens collected during the baseline study of the Guinean Nimba Mountains for the environmental impact assessment for a proposed mining project. While material belonging to this species was mentioned as early as 1920 by Chevalier, it has historically been confused with P. microbambusa, from which it differs by its typically Polystachya-like clustered pseudobulbs, placing it in P. sect. Polystachya, whereas P. microbambusa has pseudobulbs successively growing on top of one another, forming developed and persistent stems, and is the sole representative of P. sect. Dimorphocaules. The complex taxonomic and nomenclatural history of P. microbambusa is also clarified. For both taxa we provide a morphological description as well as information on distribution, habitat, and phenology, an IUCN conservation status assessment using the Red List criteria, and a distribution map, along with a dichotomous key that also includes the most similar members of P. sect. Polystachya.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Novitates Gabonenses 91: additions to the grass flora of Gabon

Background – The number of vascular plant species known to occur in Gabon rises quickly due to renewed collecting and inventory activities, often in little-known or previously uncollected areas.Methods – Herbarium material from BR, BRLU and WAG was studied.Results – Two genera (Alloteropsis, Entolasia), eleven species and one variety of grasses are recorded from Gabon for the first time (Alloteropsis paniculata, Cenchrus echinatus, Elionurus platypus, Entolasia olivacea, Eragrostis patens, Hyparrhenia diplandra var. mutica, Leersia triandra, Loudetia annua, Oryza longistaminata, Rottboellia purpurascens, Sacciolepis africana and Setaria geminata), while information on two erroneous species reports is provided. This brings the total number of grass species known to occur in Gabon to 190. Finally, new records of four rare species (Elionurus hensii, Guaduella macrostachys, Paratheria prostrata and Puelia schumanniana) are discussed

Novitates Gabonenses 88: additions to the flora of Gabon and new records of little-known species

Background and aims – The intensive botanical prospections carried out in Gabon since the publication of the national checklist in 2006 have resulted in c. 34 300 new specimens (amounting to 30% of all collections made in the country) and an annual increase of 25 species in average. As a result, 5175 species of vascular plants are now recorded from Gabon, of which 650 are considered endemic. However, most of the recent discoveries have not yet been published. This paper is the first of a series documenting additions to the flora of Gabon, and new records of poorly known species. It concerns specifically new records from the Lower Ogooué Ramsar site, the third largest delta of Africa, and certainly the most intact, which includes 80% of the country’s wetlands and a wide variety of other habitats.Methods – The new records presented here come essentially from fieldwork conducted in Gabon between 2008 and 2016 by the authors and colleagues. Further information comes from the study of herbarium specimens in BR, BRLU, K, LBV, MO, P and WAG. For each species, information on distribution and ecology is given, and the studied Gabonese collections listed. In case of rare or range-restricted species, collections from other countries are also listed, and a distribution map is provided, as well as an evaluation of the conservation status based on the categories and criteria of the IUCN Red List.Key results – We report 18 additions to the flora of Gabon, including four genera new to the country (Capparis, Gisekia, Hoffmanniella and Leptochloa) and the first records of the neotropical Justicia secunda being naturalised in tropical Africa. New distribution records are also provided for 16 rare Gabonese endemics or near-endemics. Some species are also newly reported from Cameroon (Cissus leemansii, Salacia coronata) and Equatorial Guinea (Cissus leemansii, C. louisii, Lychnodiscus grandifolius, Placodiscus resendeanus, Rutidea gabonensis, Uvaria bipindensis). Two species, which were reported in the 2006 checklist based on misidentifications, are excluded from the Gabonese flora

An efficient method for defining plant species under High Conservation Value (HCV) criterion 1 based on the IUCN Red List criteria: A case study using species endemic to Gabon

International audienceThe 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

Characteristics and Determinants of Endemic Plant Taxa in the Gabonese Area of Endemism

Endemism is one of the most important concepts in biogeography and is often used to guide biodiversity conservation, yet our understanding of the determinants of endemism in many biodiverse tropical regions is limited. This is true for western Central Africa, a region with one of the highest levels of plant diversity in tropical Africa, where endemism is poorly documented. This study examines the Gabonese Area of Endemism (GAE) and explores the main characteristics and determinants of its vascular plant endemism with regard to taxonomy, growth form, habitat, distribution, and range size. We compiled a comprehensive, verified specimen database of vascular plant taxa restricted to the GAE, comprising 19,876 occurrences of 1145 species and infraspecific taxa, and we characterized the habitat and habit for each taxon. We then calculated the proportion of taxa in the regional flora that are endemic to the GAE. A Wilcoxon rank-sum test was used to investigate range size among endemic taxa exhibiting different growth forms, and Fisher exact tests were used to explore the association between their habit and habitat, and to test the distribution of these attributes among higher-level taxa and growth forms compared to patterns in the regional flora as a whole. We found that endemic taxa represent ca. 13% of the GAE flora, and that the rate of endemism varies considerably among taxonomic groups and growth forms. Endemism is highest among shrubs (22%) and lowest in herbs (8%), especially monocotyledons (e.g. 5% among Poales). Most endemic taxa grow preferentially in forest habitats, the dominant vegetation type of the region. Endemic trees, which structure forest ecosystems, have significantly larger ranges than endemic herbs, climbers, and shrubs. About 17% of the flora of Gabon is endemic or subendemic to the country. Our results show that the dispersal capacity of taxa and the biogeographical history of the region appear to be critical factors in explaining differences in the rate of endemism among growth forms and taxonomic groups. Our findings also highlight the benefits of carefully building a comprehensive and verified database for studying rare and range-restricted plants, and they underscore the necessity to strengthen botanical exploration throughout western Central Africa in order to develop improved and better-informed conservation strategies.info:eu-repo/semantics/publishe