Sirdavidia, an extraordinary new genus of Annonaceae from Gabon

Flora of Cameroon - Annonaceae Vol 45

Annonaceae is a major pantropical family with 113 genera and about 2550 species. Cameroon is one of the most biodiverse countries in Africa but its flora remains incompletely known. In this volume of the Flora of Cameroon, we describe 166 native taxa representing 163 species in 28 native genera within the family Annonaceae. A total of 22 species (about 13%) are endemic to the country. We provide keys to all native genera, species, and infraspecific taxa. For each species a detailed morphological description and a map of its distribution in Cameroon are provided. Distribution maps and diversity analyses are based on a taxonomically verified database of 2073 collections. Across Africa, Cameroon is a center of diversity for Annonaceae harboring one of the highest numbers of species and genera. For example, Cameroon harbors the highest number of African species for the only pantropical genus of Annonaceae, Xylopia. Annonaceae are found across all 10 administrative regions of Cameroon but diversity is concentrated within the tropical rain forest areas situated in the south and South-West. The areas around Bipindi and Mount Cameroon show the highest levels of diversity, but this is correlated with collection effort. Line drawings and/or photographs accompany most species. One species new to science Uvariopsisetugeana Dagallier & Couvreur sp. nov. is described. We also undertake a number of nomenclatural changes such as lectotypifications, six new synonymies and two new combinations (Uvariaanisotricha (Le Thomas) Couvreur, comb. nov.; Uvariodendronfuscumvar.giganteum (Engl.) Dagallier & Couvreur, comb. nov.).

Phylogenomics of the Major Tropical Plant Family Annonaceae Using Targeted Enrichment of Nuclear Genes

Targeted enrichment and sequencing of hundreds of nuclear loci for phylogenetic reconstruction is becoming an important tool for plant systematics and evolution. Annonaceae is a major pantropical plant family with 110 genera and ca. 2,450 species, occurring across all major and minor tropical forests of the world. Baits were designed by sequencing the transcriptomes of five species from two of the largest Annonaceae subfamilies. Orthologous loci were identified. The resulting baiting kit was used to reconstruct phylogenetic relationships at two different levels using concatenated and gene tree approaches: a family wide Annonaceae analysis sampling 65 genera and a species level analysis of tribe Piptostigmateae sampling 29 species with multiple individuals per species. DNA extraction was undertaken mainly on silicagel dried leaves, with two samples from herbarium dried leaves. Our kit targets 469 exons (364,653 bp of sequence data), successfully capturing sequences from across Annonaceae. Silicagel dried and herbarium DNA worked equally well. We present for the first time a nuclear gene-based phylogenetic tree at the generic level based on 317 supercontigs. Results mainly confirm previous chloroplast based studies. However, several new relationships are found and discussed. We show significant differences in branch lengths between the two large subfamilies Annonoideae and Malmeoideae. A new tribe, Annickieae, is erected containing a single African genus Annickia. We also reconstructed a well-resolved species-level phylogenetic tree of the Piptostigmteae tribe. Our baiting kit is useful for reconstructing well-supported phylogenetic relationships within Annonaceae at different taxonomic levels. The nuclear genome is mainly concordant with plastome information with a few exceptions. Moreover, we find that substitution rate heterogeneity between the two subfamilies is also found within the nuclear compartment, and not just plastomes and ribosomal DNA as previously shown. Our results have implications for understanding the biogeography, molecular dating and evolution of Annonaceae.

Taxonomic revision of the African genus Greenwayodendron (Annonaceae)

Greenwayodendron (Annonaceae) is a tropical African genus of trees occurring mainly in rain forests. Until recently, Greenwayodendron contained only two species: Greenwayodendronoliveri from West Africa and Greenwayodendronsuaveolens from Central and East Africa. Genetic data, using chloroplast haplotypes and nuclear microsatellites as well as morphometric analyses, provided important information on the delineation of species. Greenwayodendron now contains six species, including two new species (Greenwayodendronglabrum Lissambou, Hardy & Couvreur, sp. nov. and Greenwayodendronlittorale Lissambou, Dauby & Couvreur, sp. nov.). Greenwayodendronsuaveolensvar.gabonica and Greenwayodendronsuaveolenssubsp.usambaricum are recognised as distinct species: Greenwayodendrongabonicum comb. nov. and Greenwayodendronusambaricum comb. nov., respectively. A key, detailed descriptions of morphology and geographic distributions, as well as notes on their ecology and uses are presented for all species. Preliminary conservation assessments following IUCN criteria are also provided. Two species are preliminarily identified as threatened, one as Endangered and one as Vulnerable.

A linear sequence to facilitate curation of herbarium specimens of Annonaceae

This paper provides a linear sequence of four subfamilies, 15 tribes and 106 genera of the magnoliid family Annonaceae, based on state-of-the-art and stable phylogenetic relationships. The linear sequence facilitates the organisation of Annonaceae herbarium specimens.

A mega-phylogeny of the Annonaceae: taxonomic placement of five enigmatic genera and support for a new tribe, Phoenicantheae

The Annonaceae, the largest family in the early-divergent order Magnoliales, comprises 107 genera and c. 2,400 species. Previous molecular phylogenetic studies targeting different taxa have generated large quantities of partially overlapping DNA sequence data for many species, although a large-scale phylogeny based on the maximum number of representatives has never been reconstructed. We use a supermatrix of eight chloroplast markers (rbcL, matK, ndhF, psbA-trnH, trnL-F, atpB-rbcL, trnS-G and ycf1) to reconstruct the most comprehensive tree to date, including 705 species (29%) from 105 genera (98%). This provides novel insights into the relationships of five enigmatic genera (Bocagea, Boutiquea, Cardiopetalum, Duckeanthus and Phoenicanthus). Fifteen main clades are retrieved in subfamilies Annonoideae and Malmeoideae collectively, 14 of which correspond with currently recognised tribes. Phoenicanthus cannot be accommodated in any existing tribe, however: it is retrieved as sister to a clade comprising the tribes Dendrokingstonieae, Monocarpieae and Miliuseae, and we therefore validate a new tribe, Phoenicantheae. Our results provide strong support for many previously recognised groups, but also indicate non-monophyly of several genera (Desmopsis, Friesodielsia, Klarobelia, Oxandra, Piptostigma and Stenanona). The relationships of these non-monophyletic genera-and two other genera (Froesiodendron and Melodorum) not yet sampled-are discussed, with recommendations for future research.

Exploring the floristic diversity of tropical Africa

BACKGROUND

Understanding the patterns of biodiversity distribution and what influences them is a fundamental pre-requisite for effective conservation and sustainable utilisation of biodiversity. Such knowledge is increasingly urgent as biodiversity responds to the ongoing effects of global climate change. Nowhere is this more acute than in species-rich tropical Africa, where so little is known about plant diversity and its distribution. In this paper, we use RAINBIO - one of the largest mega-databases of tropical African vascular plant species distributions ever compiled - to address questions about plant and growth form diversity across tropical Africa.

RESULTS

The filtered RAINBIO dataset contains 609,776 georeferenced records representing 22,577 species. Growth form data are recorded for 97% of all species. Records are well distributed, but heterogeneous across the continent. Overall, tropical Africa remains poorly sampled. When using sampling units (SU) of 0.5°, just 21 reach appropriate collection density and sampling completeness, and the average number of records per species per SU is only 1.84. Species richness (observed and estimated) and endemism figures per country are provided. Benin, Cameroon, Gabon, Ivory Coast and Liberia appear as the botanically best-explored countries, but none are optimally explored. Forests in the region contain 15,387 vascular plant species, of which 3013 are trees, representing 5-7% of the estimated world's tropical tree flora. The central African forests have the highest endemism rate across Africa, with approximately 30% of species being endemic.

CONCLUSIONS

The botanical exploration of tropical Africa is far from complete, underlining the need for intensified inventories and digitization. We propose priority target areas for future sampling efforts, mainly focused on Tanzania, Atlantic Central Africa and West Africa. The observed number of tree species for African forests is smaller than those estimated from global tree data, suggesting that a significant number of species are yet to be discovered. Our data provide a solid basis for a more sustainable management and improved conservation of tropical Africa's unique flora, and is important for achieving Objective 1 of the Global Strategy for Plant Conservation 2011-2020. In turn, RAINBIO provides a solid basis for a more sustainable management and improved conservation of tropical Africa's unique flora.

Two new records of palm species for Gabon: Sclerosperma profizianum Valk. & Sunder. and Eremospatha quiquecostulata Becc

Background

Gabon is an important center of biodiversity in Central Africa. The country contains to date 27 species of palms. However, palms are generally poorly collected as these massive plants are hard to press and curate. Thus, our understanding remains incomplete, especially in Central Africa.

New information

We report three new records of two palm species for Gabon: Sclerospermaprofizianum Valk. & Sunder. and Eremospathaquiquecostulata Becc.. The former species was collected in southeast Gabon, near Ndindi, while the later was collected in the Massif du Chaillu and Monts de Cristal National Park (Crystal Mountains National Park). The total number of palm species for Gabon is now 29, making it an important centre of palm diversity in Central Africa.

New species of Uvariopsis (Annonaceae) and Laccosperma (Arecaceae/Palmae) from Monts de Cristal, Gabon

Monts de Cristal National Park in northwest Gabon is one of the most species rich places in Central Africa. Here, we describe two new species, one in Annonaceae and one in palms. Uvariopsis citrata Couvreur & Niangadouma, sp. nov. is unique in the genus by emitting a strong lemon scent from the crushed leaves and young branches. Laccosperma cristalensis Couvreur & Niangadouma, sp. nov. is a rattan that lacks acanthophylls on the cirrus and has few pinnae. Complete descriptions, photographic illustrations, ecological information and preliminary IUCN conservation status are provided. For both species a data deficient (DD) status is proposed. These new species underline once again that the Monts de Cristal National Park is yet incompletely known botanically.