Septoglomus nigrum, a new arbuscular mycorrhizal fungus from France, Germany and Switzerland

A new arbuscular mycorrhizal fungus, Septoglomus nigrum, was found in several agricultural field sites in France, Germany and Switzerland, especially in extensively to intensively managed natural meadows and pastures and in extensively managed cropping systems. The fungus was propagated in trap pots and single species cultures on Lolium perenne, Trifolium pratense, Plantago lanceolata and Hieracium pilosella. It differentiates black spores with triple-layered walls, 95–175× 90–170 μm in diameter, formed singly in soils or rarely in roots. Phylogenetically, it forms a distinct clade close to S. altomontanum and S. africanum, which can morphologically be distinguished from spores of S. nigrum by the characteristics of the spore wall and by the color, size and shape of the subtending hyphae. An identification key is provided that differentiates all species so far described in Septoglomus.This study has been supported by the Swiss National Science Foundation within the SNSF projects 315230_130764/1, IZ73Z0_152740 and IZ76Z0_173895. We are also grateful to Urs Zihlmann (Agroscope in Zürich-Reckenholz) and our collaborators Claudia Maurer, Andres Chervet and Wolfgang Sturny at the Bodenschutzfachstelle of the Kanton Bern for the excellent support at the lowland sampling sites. G.A Silva thanks the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for the Fellowship granted (Proc. 312186/2016-9).Peer Reviewe