Miguel E. Leal

Global sampling of plant roots expands the described molecular diversity of arbuscular mycorrhizal fungi.

We aimed to enhance understanding of the molecular diversity of arbuscular mycorrhizal fungi (AMF) by building a new global dataset targeting previously unstudied geographical areas. In total, we sampled 96 plant species from 25 sites that encompassed all continents except Antarctica. AMF in plant roots were detected by sequencing the nuclear SSU rRNA gene fragment using either cloning followed by Sanger sequencing or 454-sequencing. A total of 204 AMF phylogroups (virtual taxa, VT) were recorded, increasing the described number of Glomeromycota VT from 308 to 341 globally. Novel VT were detected from 21 sites; three novel but nevertheless widespread VT (Glomus spp. MO-G52, MO-G53, MO-G57) were recorded from six continents. The largest increases in regional VT number were recorded in previously little-studied Oceania and in the boreal and polar climatic zones — this study providing the first molecular data from the latter. Ordination revealed differences in AM fungal communities between different continents and climatic zones, suggesting that both biogeographic history and environmental conditions underlie the global variation of those communities. Our results show that a considerable proportion of Glomeromycota diversity has been recorded in many regions, though further large increases in richness can be expected in remaining unstudied areas.

Enzymatic activities and stable isotope patterns of ectomycorrhizal fungi in relation to phylogeny and exploration types in an afrotropical rain forest

Ectomycorrhizal (ECM) fungi obtain both mineral and simple organic nutrients from soil and transport these to plant roots. Natural abundance of stable isotopes (¹⁵N and ¹³C) in fruit bodies and potential enzymatic activities of ECM root tips provide insights into mineral nutrition of these mutualistic partners. By combining rDNA sequence analysis with enzymatic and stable isotope assays of root tips, we hypothesized that phylogenetic affinities of ECM fungi are more important than ECM exploration type, soil horizon and host plant in explaining the differences in mineral nutrition of trees in an African lowland rainforest. Ectomycorrhizal fungal species belonging to extraradical mycelium-rich morphotypes generally displayed the strongest potential activities of degradation enzymes, except for laccase. The signature of ¹⁵N was determined by the ECM fungal lineage, but not by the exploration type. Potential enzymatic activities of root tips were unrelated to ¹⁵N signature of ECM root tip. The lack of correlation suggests that these methods address different aspects in plant nutrient uptake. Stable isotope analysis of root tips could provide an additional indirect assessment of fungal and plant nutrition that enables enhancement of taxonomic coverage and control for soil depth and internal nitrogen cycling in fungal tissues.

Spatial structure and the effects of host and soil environments on communities of ectomycorrhizal fungi in wooded savannas and rain forests of Continental Africa and Madagascar

Mycorrhizal fungi play a key role in mineral nutrition of terrestrial plants, but the factors affecting natural distribution, diversity and community composition of particularly tropical fungi remain poorly understood. This study addresses shifts in community structure and species frequency of ectomycorrhizal (EcM) fungi in relation to host taxa, soil depth and spatial structure in four contrasting African ecosystems. We used the rDNA and plastid trnL intron sequence analysis for identification of fungi and host plants, respectively. By partitioning out spatial autocorrelation in plant and fungal distribution, we suggest that African EcM fungal communities are little structured by soil horizon and host at the plant species and family levels. These findings contrast with patterns of vegetation in these forests and EcM fungal communities in other tropical and temperate ecosystems. The low level of host preference indirectly supports an earlier hypothesis that pioneer Phyllanthaceae may facilitate the establishment of late successional Fabaceae and potentially other EcM host trees by providing compatible fungal inoculum in deforested and naturally disturbed ecosystems of tropical Africa.

The past protecting the future

Purpose – In answer to the urgent need to adapt conservation strategies and approaches to climate change, the purpose of this paper is to locate the climatically stable forests in West and Central Africa and to assess whether they overlap with the existing network of protected areas and if not, to prioritize them for protection.Design/methodology/approach – With ongoing global warming, rain forest will survive where locally soil moisture content remains high compensating for the regional drought stress. As a proxy for a soil moisture‐driven model, rainfall >2,000 mm, altitude >500 m and strong relief (standard deviation in elevation data pixels) were overlapped in a GIS analysis to locate the climatically stable forest within the present continuous forest of Central Africa and within the degraded forest of West Africa. As a means of verification, the biodiversity was measured in and outside the identified areas in Gabon and Equatorial Guinea as high levels of biodiversity are related to the survival and s...

NOVITATES RIO MUNIS 1. A NEW ENDEMIC SCAPHOPETALUM (MALVACEAE) FROM MOUNT MITRA, EQUATORIAL GUINEA

SUMMARY A new species of Scaphopetalum from Monte Mitra is described. Small shrub 20-150 cm tall. Petiole 3-5 mm. Leaves obovate, glabrous and shiny, 7.5-13 by 2.5-5.5 cm, base rounded, apex shortly caudate. Inflorescence raminascent, few-flowered cymes, peduncle 3-4 mm long, 1-5 flowers, pedicel 2-3 cm. Sepals 9-10 by 4-3 mm narrowly ovate, hairy on the inside of the tip. Petals hooded, whitish transparent and ribbed, 0.8-1 by 0.5-0.7 cm, apex with three short slips. Stamens fused in vase-like tube, 1 cm diam. and 0.5 cm high, with 5 sharply angled lobes, each lobe has a red ray, anthers inserted on the lobes. Ovary 5-lobed, style 1 mm long. Capsule glabrous, 1.5-2 by 0.6-0.9 cm, with 5 sharply angled ridges. Seeds 2 mm, adorned with a brown aril. Distribution — Equatorial Guinea, at the base of Monte Mitra. Habitat — Understorey of (submontane) rain forest at an altitude of 700 m. Note — Equatorial Guinea is the only country in central Africa without a national flora. Some believe that such a reference book is not needed arguing that the plants of Equatorial Guinea are completely a subset of those found in Cameroon and Gabon

Dorstenialuamensis (Moraceae), a new species from eastern Democratic Republic of Congo.

Abstract A new species of Dorstenia L. (Moraceae), Dorstenia luamensis M.E.Leal, is described from the Luama Wildlife Reserve, west of Lake Tanganyika and north of the town of Kalemie in the eastern part of the Democratic Republic of Congo (DRC). This species is endemic to the region and differs from any of the other species by its fernlike lithophytic habit and lack of latex. A description and illustration of this species is presented here. Dorstenia luamensis M.E.Leal inhabits moist and shady vertical rock faces close to small waterfalls in the forest; the species is distributed in small populations within the type locality, and merits the conservation status of endangered (EN).

NOVITATES GABONENSES 61. A NEW RARE ENDEMIC CALVOA (MELASTOMATACEAE) FROM MBE NATIONAL PARK, GABON

SUMMARY A new species of Calvoa from the Mbe National Park, Monts de Cristal is described. Small herb, 2-3 cm high, terrestrial, dark green, hirsute with 1 mm long white hairs; branches slightly angular. Petiole 7-10 mm. Lamina ovate truncate to cuneate, 1.1-2 (-3.8) by 1.5-2.5 cm, margin serrulate ciliate, apex acute, three main veins, sparse slender hairs surrounded by a white dot (0.2 mm diameter) above, below whitish green with hairs on the veins. Inflorescence a terminal single-branched cyme, sessile or with a 0.5 cm long peduncle, with 1-6 sessile flowers. Hypanthium 1.5-2.5 mm long, densely hirsute. Calyx lobes 1.5-2 by 0.1-0.3 mm triangular with a truncate apex. Petals 4-5 by 3-4 mm white. Anthers 1 mm long. Style 1-2 mm long, stigma capitate. Capsule 3-4 by 5-6 mm hirsute; with a 5-lobed crown exerted for 1.5 mm and frimbricate. Seeds 0.5 mm.

NOVITATES GABONENSES 65. A NEW RARE ENDEMIC AMPHIBLEMMA (MELASTOMATACEAE) FROM MVE LAKENE, GABON

SUMMARY A new species of Amphiblemma from the Mve Lakene Plateau, Monts de Cristal is described.