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Paraglomus majewskii sp. nov. (Glomeromycota) is described and illustrated. It forms single spores, which are hyaline through their life cycle, globose to subglobose, (35-)63(-78) μm diam, sometimes egg-shaped, 50-70 × 65-90 μm, and have an unusually narrow, (3.2-)4.6(-5.9) μm, cylindrical to slightly flared subtending hypha. The spore wall of P. majewskii consists of an evanescent, short-lived outermost layer, a laminate middle layer, and a flexible innermost layer, which adheres tightly to the middle layer. None of the spore wall layers stain in Melzer's reagent. In single-species cultures with Plantago lanceolata as the host plant P. majewskii formed arbuscular mycorrhizae staining violet in trypan blue. P. majewskii has been isolated from several, distant geographic regions and from different habitats. In phylogenetic analyses of partial nrDNA SSU and LSU sequences the fungus formed mono-phyletic group with Paraglomus species; however it represents a well separated distinct lineage. Its nrDNA sequences are highly similar to in planta arbuscular mycorrhizal fungal sequences from different habitats in Spain and Ecuador.

In order to recognize interactions between alien vascular plants and soil microorganisms and thus better understand the mechanisms of plant invasions, we examined the mycorrhizal status, arbuscular mycorrhizal fungi (AMF) colonization rate, arbuscular mycorrhiza (AM) morphology and presence of fungal root endophytes in 37 non-native species in Central Europe. We also studied the AMF diversity and chemical properties of soils from under these species. The plant and soil materials were collected in southern Poland. We found that 35 of the species formed AM and their mycorrhizal status depended on species identity. Thirty-three taxa had AM of Arum-type alone. Lycopersicon esculentum showed intermediate AM morphology and Eragrostis albensis developed both Arum and Paris. The mycelia of dark septate endophytes (DSE) were observed in 32 of the species, while sporangia of Olpidium spp. were found in the roots of 10. Thirteen common and worldwide occurring AMF species as well as three unidentified spore morphotypes were isolated from trap cultures established with the soils from under the plant species. Claroideoglomus claroideum, Funneliformis mosseae and Septoglomus constrictum were found the most frequently. The presence of root-inhabiting fungi and the intensity of their colonization were not correlated with soil chemical properties, plant invasion status, their local abundance and habitat type. No relationships were also found between the presence of AMF, DSE and Olpidium spp. These suggest that other edaphic conditions, plant and fungal species identity or the abundance of these fungi in soils might have an impact on the occurrence and intensity of fungal root colonization in the plants under study.Electronic supplementary materialThe online version of this article (doi:10.1007/s13199-015-0324-4) contains supplementary material, which is available to authorized users.

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