The vascular plant diversity of Burundi

Background and aims – The vascular plant diversity of Burundi is still insufficiently explored, described, and understood. The goal of this paper is to show the degree of botanical exploration and the spatial patterns of botanical diversity in Burundi to date. Material and methods – The study is based on a dataset containing virtually all plant collections, observed in herbaria, recorded in databases, or cited in literature, made in Burundi. All data were compiled, cleaned, and each record georeferenced. Various distribution analyses were carried out, some of which were based on a grid of 199 hexagonal cells. Key results – The dataset comprises 37,200 herbarium collections representing 3,860 species grouped in 1,290 genera and 216 families. The expected species richness is estimated at 4,869. The average number of collections per species is 8.8, but 1,149 species (27%) are sampled only once. The seven most species-rich families are Fabaceae (539 spp.), Poaceae (387), Asteraceae (298), Orchidaceae (286), Cyperaceae (272), Rubiaceae (227), and Acanthaceae (128), which together account for over 50% of the vascular plant flora of Burundi. The seven largest genera are Cyperus (90 spp.), Crotalaria (60), Indigofera (50), Polystachya (48), Habenaria (47), Vernonia (45), and Eragrostis (41). In terms of number of herbarium collections, the six most important families are Poaceae (4,754 collections), Fabaceae (4,300), Asteraceae (2,226), Rubiaceae (2,191), Cyperaceae (1,730), and Lamiaceae (1,275). The four areas most intensively explored and with the highest known species diversity are the Rusizi plain, the Kibira rain forest belonging to the Albertine Rift, the Bururi and Rumonge areas in the west, and the Mosso depression in the east. Conclusion – With a collecting index of 133 collections per 100 km2, the botanical exploration of Burundi can be considered as relatively good. However, 28% of the species are only represented by a single record and some 1,000 species are potentially present but have remained uncollected to date. For every 100 new collections, there are on average 6 new species records, indicating that Burundi’s inventory is still not complete

Four new endemic genera of Rubiaceae (Pavetteae) from Madagascar represent multiple radiations into drylands

The taxonomic positions and phylogenetic relationships of six Pavetteae species endemic to Madagascar were tested with a phylogenetic study of the Afro-Madagascan representatives of the tribe Pavetteae based on sequence data from six markers rps16, trnT-F, petD, accD-psa1, PI and ITS. The six species were resolved into four well-supported and morphologically distinct clades which we here formally recognise at generic level. The new genera are the monospecific Exallosperma and Pseudocoptosperma, each with a single species, and Helictosperma and Tulearia, each with two species. Each genus is characterised by one or more autapomorphies or by a unique combination of plesiomorphic characters. Mostly, the distinguishing characters are found in fruit and seed; Exallosperma differs from all other Pavetteae genera by the fruit consisting of two stony pyrenes, each with a single laterally flattened seed with irregularly distributed ridges on the surface; Helictosperma is unique by its single spherical seed rolled-in on itself in the shape of a giant pill-millipede. Pseudocoptosperma is characterised by the combination of three ovules pendulous from a small placenta and triangular stipules with a strongly developed awn, whereas Tulearia is characterised by robust sericeous flowers, small leaves, uni- or pauciflorous inflorescences and fruits with two pyrenes, each with a single ruminate seed. The four new genera show marked adaptations to the dry habitats in which they grow. They represent multiple radiations into drylands and highlight the importance of the dry forest and scrub vegetation in western, southern and northern Madagascar for plant biodiversity. The description of the four new genera shows that the tribe Pavetteae exhibits the same pattern as many plant groups in Madagascar, which are characterised by a high proportion of endemic genera comprising a single or a few species. In the four new genera, five new species are described and one new combination is made: Exallosperma longiflora De Block; Helictosperma malacophylla (Drake) De Block, Helictosperma poissoniana De Block, Pseudocoptosperma menabense Capuron ex De Block; Tulearia capsaintemariensis De Block and Tulearia splendida De Block

Genetic diversity of wild and cultivated Coffea canephora in northeastern DR Congo and the implications for conservation

Premise Many cultivated coffee varieties descend from Coffea canephora, commonly known as Robusta coffee. The Congo Basin has a century-long history of Robusta coffee cultivation and breeding, and is hypothesized to be the region of origin of many of the cultivated Robusta varieties. Since little is known about the genetic composition of C. canephora in this region, we assessed the genetic diversity of wild and cultivated C. canephora shrubs in the Democratic Republic of the Congo. Methods Using 18 microsatellite markers, we studied the genetic composition of wild and backyard-grown C. canephora shrubs in the Tshopo and Ituri provinces and multiple accessions from the INERA Yangambi Coffee Collection. We assessed genetic clustering patterns, genetic diversity, and genetic differentiation between populations. Results Genetic differentiation was relatively strong between wild and cultivated C. canephora shrubs, and both gene pools harbored multiple unique alleles. Strong genetic differentiation was also observed between wild populations. The level of genetic diversity in wild populations was similar to that of the INERA Yangambi Coffee Collection, but local wild genotypes were mostly missing from that collection. Shrubs grown in the backyards were genetically similar to the breeding material from INERA Yangambi. Conclusions Most C. canephora that is grown in local backyards originated from INERA breeding programs, while a few shrubs were obtained directly from surrounding forests. The INERA Yangambi Coffee Collection could benefit from an enrichment with local wild genotypes to increase the genetic resources available for breeding purposes and to support ex situ conservation

Conservation et gestion de la biodiversité

First paragraph: Since the first edition of the State of the Forest (SOF), the state and conservation of biodiversity have been a continuing concern. Every subsequent edition has reviewed the threats to the fauna and flora of the subregion. In 2010, the subject was presented in a chapter entitled "Biodiversity in the forests of Central Africa: panorama of knowledge, principal challenges and conservation measures" (Billand, 2012). By devoting a new chapter to this subject, the SOF 2013 reaffirms the importance of biodiversity and the protection of species for the sustainable development of the forests of Central Africa

The ECAT dataset: expert-validated distribution data of endemic and sub-endemic trees of Central Africa (Dem. Rep. Congo, Rwanda, Burundi)

International audienceIn 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