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Memecylon batekeanum R. D. Stone & G. M. Walters. —A. Flowering branch. —B. Inflorescence with calyptrate calyx. —C. Flower with three petals removed. —D. Petal. —E. Anther, frontal view. —F. Anther, lateral view. —G. Leaf, abaxial surface. —H. Leaf, adaxial surface. Drawn from the holotype Walters et al. 967 (MO).
Source publication
Dans ce travail est décrit et illustré Memecylon batekeanum R. D. Stone & G. M. Walters du zone tampon du Parc National des Plateaux Batéké du Sud-est Gabon. Cette nouvelle espèce se rapproche de l'espèce Camerounaise M. amshoffiae Jacques-Félix, mais s'en distingue par sa forme d'arbrisseau, ses jeunes rameaux 4-angulaires-ailés, ses cymes peu fle...
Context in source publication
Citations
... Future botanical work should focus on the forest, especially its riverine forests, but also the under-collected areas of the southern part of the PNPB. Our checklist shows few forest flora endemic species, however, Memecylon batekeanum (Stone et al. 2006) forms part of a monophyletic group with M. amshoffiae and M. diluviorum, a clade from riverine forests in Cameroon, Gabon, and Angola (Cabinda) (Stone 2014), potentially indicating a unique diversity for these habitats. An additional rare species to consider is Syngonananthus poggeanus Ruhland, known from the Haut Ogooué, along the Republic of Congo border, from sandy wetlands, and although it is not currently known from the study area, it could be collected there in the future (Phillips 2016: 18). ...
Background and aims – Old-growth savannas in Africa are impacted by fire, have endemic and geoxylic suffrutices, and are understudied. This paper explores the Parc National des Plateaux Batéké (PNPB) in Gabon and the impact of fire on its flora to understand if it is an old-growth savanna. It presents 1) a vascular plant checklist, including endemic species and geoxylic suffrutices and 2) an analysis of the impact of fire on the savanna herbaceous flora, followed by recommendations for fire management to promote plant diversity.
Material and methods – 1,914 botanical collections from 2001–2019 collected by the authors and others were extracted from two herbaria databases in 2021 to create the checklist. The impact of fire was explored through a three season plot-based inventory of plant species (notably forbs and geoxylic suffrutices) in five annually, dry-season burned study areas located at 600 m in elevation. A two-factor ANOVA was conducted across two burn treatments and three season treatments.
Key results – The area has a vascular flora of 615 taxa. Seven species are endemic to the Plateaux Batéké forest-savanna mosaic. Seventeen species are fire-dependent geoxylic suffrutices, attesting to the ancient origins of these savannas. Burning promotes fire-dependent species.
Conclusion – The PNPB aims to create a culturally-adapted fire management plan. The combination of customary fire and fire-adapted species in the savanna creates a unique ancient forest-savanna mosaic in Central Africa that merits protection while recognising the role that the Batéké-Alima people have in shaping and governing this landscape.
... Mouririoidea (excluding M. amshoffiae, cf. Stone & al., 2006) and the remaining paleotropical taxa of the genus (bootstrap 100%). Within the main Memecylon clade (excluding M. sect. ...
... This result indicates that M. sect. Mouriri oidea sensu Jacques-Félix (1979) is polyphyletic unless its circumscription excludes M. amshoffiae, a conclusion further supported by morphological evidence (Stone & al., 2006). Also phylogenetically nested within this second species-group from western and central Africa is M. flavovirens, which is the type species of M. sect. ...
... -The Cameroon endemic M. amshoffiae, originally placed in sect. Mouririoidea, has been excluded from this group on morphological and molecular evidence (Stone & al., 2006;Fig. 2 Soc. ...
The internal and external transcribed spacers of nuclear ribosomal DNA were sequenced in 167 samples of Memecylon s.str. and 22 outgroup samples of Lijndenia, Mouriri, Spathandra, Votomita, and Warneckea. Maximum-likelihood analyses of ETS, ITS1, 5.8S and ITS2 alignments yielded tree topologies that are not significantly incongruent, with one exception involving the Tanzanian sample Luke 9741. Monophyly of Memecylon s.str. is strongly supported in the separate ETS and the combined ETS + ITS1 + 5.8S + ITS2 analyses. Also supported in all analyses except 5.8S is a sister-group relationship between a small species-group from western and central Africa (Memecylon subg. Mouririoidea, ovary 4-loculed) and the remaining taxa (M. subg. Memecylon, ovary unilocular). In the combined analysis, internal branches at the base of M. subg. Memecylon are short and weakly supported, yet within this large subgenus one finds a series of monophyletic groups representing different parts of the widespread paleotropical distribution (one group in western and central Africa; two separate groups in East Africa, one of these extending to southern Africa and disjunctly to western and northern Madagascar; one species-rich group occurring exclusively on Madagascar and the neighboring Comoro and Mascarene islands; and three distinct groups in Indo-Malesia, one of these also including the Seychelles endemic M. elaeagni). Within the western and central African clade, M. sect. Polyanthema sensu Jacques-Félix is paraphyletic with respect to M. sect. Afzeliana, and at the morphological level it seems to be a group defined by symplesiomorphies (ovary unilocular, fruit globose). Three East African species (M. fragrans, M. greenwayi, M. semseii) are returned to Memecylon s.str. after being erroneously transferred to Lijndenia by Borhidi. The Madagascan endemic M. mocquerysii is no longer considered a taxonomic synonym of the distantly related, Tanzanian M. cogniauxii. In addition to elevating M. sect. Mouririoidea to subgeneric rank, the following changes are proposed in the infrageneric classification of African Memecylon: (1) the circumscription of sect. Polyanthema is narrowed to comprise only the members of the “M. polyanthemos complex” sensu Jacques-Félix; (2) Engler's sections Tenuipedunculata, Cauliflora, and Obtusifolia are re-instated with emended descriptions (in the case of sect. Cauliflora with an expanded circumscription); (3) seven new sections, Buxifolia, Diluviana, Felixiocylon, Germainiocylon, Magnifoliata, Montana, and Sitacylon, are described; (4) the purported occurrence of M. sect. Pseudonaxiandra in East Africa is rejected. A key is provided to the two subgenera and twelve sections currently recognized in African Memecylon. Further study is needed toward a sectional classification of Indo-Malesian Memecylon, and for revision of the seven Madagascan sections recognized by Jacques-Félix.
... All articles are listed on a website (Website Novitates Gabonenses). Recent discoveries published by botanists from a variety of institutions (many published in this series) come from several phytogeographical areas in Gabon including the coastal plain (Dauby et al. 2007, Mackinder & Wieringa 2007, Sosef et al. 2007, Breteler 2010; mountainous areas (Leal 2005, Bissiengou & Sosef 2008, Ntore et al. 2009), as well as the continental area (Stone et al. 2006, Goyder 2009). ...
... NIA has three intron regions and has been shown to be single-copy in some plants, where it is useful for low-level phylogenetic analyses. NIA has been used in phylogenetic studies for Betula ( Li et al. 2007 ), Boerhavia ( Douglas 2007 ), Memecylon ( Stone et al. 2006 ), and Scaevola ( Howarth and Baum 2002 ). In this study, we used nitrate reductase sequence data from an intron of NIA and its flanking regions to investigate the phylogeny of Solanum sect. ...
Solanum section Petota is taxonomically difficult, partly because of interspecific hybridization at both the diploid and polyploid levels. There is much disagreement regarding species boundaries and affiliation of species to series. Elucidating the phylogenetic relationships within the polyploids is crucial for an effective taxonomic treatment of the section and for the utilization of wild potato germplasm in breeding programs. We here infer relationships among the potato diploids and polyploids using nitrate reductase (NIA) sequence data in comparison to prior plastid phylogenies and: 1) examine genome types within section Petota, 2) show species in the polyploid series Conicibaccata, Longipedicellata, and in the Iopetalum group to be derived from allopolyploidization, 3) support an earlier hypothesis by confirming S. verrucosum as the maternal genome donor for the polyploid species S. demissum as well as species in the Iopetalum Group, 4) demonstrate that S. verrucosum is the closest relative to the maternal genome donor for species in ser. Longipedicellata, 5) support the close relationship between S. acaule and diploid species from series Megistacroloba and Tuberosa, and 6) show the North and Central American B genome species to be well distinguished from the A genome species of South America.
Premise:
The woody plant group Memecylon (Melastomataceae) is a large clade occupying diverse forest habitats in the Old World tropics and exhibiting high regional endemism. Its phylogenetic relationships have been previously studied using ribosomal DNA with extensive sampling from Africa and Madagascar. However, divergence times, biogeography, and character evolution of Memecylon remain uninvestigated. We present a phylogenomic analysis of Memecylon to provide a broad evolutionary perspective of this clade.
Methods:
One hundred supercontigs of 67 Memecylon taxa were harvested from target enrichment. The data were subjected to coalescent and concatenated phylogenetic analyses. A timeline was provided for Memecylon evolution using fossils and secondary calibration. The calibrated Memecylon phylogeny was used to elucidate its biogeography and ancestral character states.
Results:
Relationships recovered by the phylogenomic analyses are strongly supported in both maximum likelihood and coalescent-based species trees. Memecylon is inferred to have originated in Africa in the Eocene and subsequently dispersed predominantly eastward via long-distance dispersal (LDD), although a reverse dispersal from South Asia westward to the Seychelles was postulated. Morphological data exhibited high levels of homoplasy, but also showed that several vegetative and reproductive characters were phylogenetically informative.
Conclusions:
The current distribution of Memecylon appears to be the result of multiple ancestral LDD events. Our results demonstrate the importance of the combined effect of geographic and paleoclimatic factors in shaping the distribution of this group in the Old World tropics. Memecylon includes a number of evolutionarily derived morphological features that contribute to diversity within the clade.
Background – A new species of Memecylon (Melastomataceae–Olisbeoideae) from Rwanda, Burundi and western Tanzania is described in connection with preparing the family treatment for the Flore d’Afrique centrale. Methods – Standard herbarium practices were applied.Key results – Memecylon afroschismaticum R.D.Stone is described and illustrated. This new species is remarkable for being endemic to forests of the East African Rift region avoided by all but a few other species of African Memecylon. A close relationship with M. flavovirens Baker (type of M. sect. Obtusifolia Engl.) is suggested by its corolla being narrowly conical-acute in bud and anther connectives with dorsal oil-gland and acute posterior extremity. However, its elliptic-ovate and distinctly acuminate leaves resemble those of M. myrianthum Gilg (of M. sect. Polyanthema Engl.) and M. verruculosum Brenan (of M. sect. Buxifolia R.D.Stone). The known location in western Tanzania is formally protected within the Mahale Mountains National Park, but the subpopulations in Rwanda and Burundi are unprotected and presumably threatened by high human population density and subsistence agriculture. The estimated area of occupancy is also quite small (12 km2). Memecylon afroschismaticum is thus provisionally assessed as Endangered [EN B1ab(iii)+B2ab(iii)] in accordance with IUCN criteria.
Background and aims - Further studies of Madagascan Memecylon have revealed that much of the herbarium material collected in the last 25 years is undescribed. As a prelude to a comprehensive taxonomic revision, the current paper presents an overview and analysis of the remarkable diversity of this genus in Madagascar. Key results - Within the paleotropical distribution of Memecylon, Madagascar contains by far the highest concentration of species proportionate to land area. All of the Madagascan Memecylon species are endemic to the island, with the majority being localized endemics known from just one or two sites. As a result of recent field- and collections-based studies, about fifty new species will be proposed. When this is done the total number of Madagascan Memecylon species will increase to 138 (representing a 70% increase from our state of knowledge in 1985). Memecylon is clearly one of the plant genera that has radiated extensively on the island. Floral morphology is strongly conserved, but leaf morphology and inflorescence position are quite variable and often diagnostic at the species level. In several cases, different species have converged on similar vegetative morphologies, leading to taxonomic confusion. Conclusions - When making species determinations in Madagascan Memecylon, both morphological features and ecogeographic factors should be taken into account. Comprehensive taxonomic revisions in species-rich groups like Memecylon are a prerequisite for further study of the mechanisms of species diversification on the island.
Background On-going botanical research in Gabon continues to yield species new to science, in this case a new member of the leguminous genus Eriosema. Material and methods Normal practices of herbarium taxonomy have been applied; material is present in LBV, MO, and WAG. Key results A new species, Eriosema batekense Maesen & G.M.Walters, is described and illustrated. The stems of the new species are not as thin as in E. youngii. The tubers are narrow-spindly and straight, vertical in the soil, not napiform as in E. youngii. Another similar species, E. linifolium, is more robust with thicker stems and rootstock. E. batekense occurs on the Bateke Plateaux in Gabon, and has also been collected from the nearby Bafuru Plateau in Congo-Brazzaville. It is restricted to Kalahari sands. The species is assessed to be of Least Concern according to the IUCN criteria.
Solanum section Petota is taxonomically difficult, partly because of interspecific hybridization at both the diploid and polyploid levels. There is much disagreement regarding species boundaries and affiliation of species to series. Elucidating the phylogenetic relationships within the polyploids is crucial for an effective taxonomic treatment of the section and for the utilization of wild potato germplasm in breeding programs. We here infer relationships among the potato diploids and polyploids using nitrate reductase ( NIA ) sequence data in comparison to prior plastid phylogenies and: 1) examine genome types within section Petota , 2) show species in the polyploid series Conicibaccata , Longipedicellata , and in the Iopetalum group to be derived from allopolyploidization, 3) support an earlier hypothesis by confirming S. verrucosum as the maternal genome donor for the polyploid species S. demissum as well as species in the Iopetalum Group, 4) demonstrate that S. verrucosum is the closest relative to the maternal genome donor for species in ser. Longipedicellata , 5) support the close relationship between S. acaule and diploid species from series Megistacroloba and Tuberosa , and 6) show the North and Central American B genome species to be well distinguished from the A genome species of South America.
