The arbuscular mycorrhizal Paraglomus majewskii sp. nov. represents a distinct basal lineage in Glomeromycota.

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.

The diversity of Terfezia desert truffles: new species and a highly variable species complex with intrasporocarpic nrDNA ITS heterogeneity.

Desert truffles belonging to Terfezia are well known mycorrhizal members of the mycota of the Mediterranean region and the Middle East. We aimed to test (i) whether the morphological criteria of Terfezia species regularly collected in Spain enable their separation and (ii) whether the previously hypothesized edaphic/biotic specificity of one group could be confirmed by study of a larger number of specimens. The species T. arenaria and T. claveryi can be identified unambiguously by morphological characters. We consider T. leptoderma as a distinct species while several lineages of similar spiny spored Terfezia truffles with cellular peridium were detected that have no obvious anatomical differences. Several species treated generally as synonyms of T. olbiensis have been described in this group, and because they cannot be unambiguously assigned to separate lineages we propose to consider the group as the T. olbiensis species complex. A high level of intrasporocarpic variation of the nrDNA ITS was detected in the T. olbiensis species complex, especially in one of its lineages. We detected no exclusive specificity to either plant associates or soil, except in T. leptoderma, which was associated with Quercus spp. and cistaceous plants on acidic soils. Nevertheless the clades showed a tendency either to associate with Quercus/Helianthemum/Cistus or Pinus hosts. Specimens having distinct anatomical features, reticulate spores and cellular peridium formed a separate group in the molecular phylogenetic analyses of nrDNA ITS and LSU regions; for these specimens we propose a new species, Terfezia alsheikhii sp. nov.

Glomus africanum and G. iranicum, two new species of arbuscular mycorrhizal fungi (Glomeromycota).

Two new arbuscular mycorrhizal fungal species (Glomeromycota) of genus Glomus, G. africanum and G. iranicum, are described and illustrated. Both species formed spores in loose clusters and singly in soil and G. iranicum sometimes inside roots. G. africanum spores are pale yellow to brownish yellow, globose to subglobose, (60-)87(-125) µm diam, sometimes ovoid to irregular, 80-110 x 90-140 µm. The spore wall consists of a semipermanent, hyaline, outer layer and a laminate, smooth, pale yellow to brownish yellow, inner layer, which always is markedly thinner than the outer layer. G. iranicum spores are hyaline to pastel yellow, globose to subglobose, (13-)40(-56) µm diam, rarely egg-shaped, prolate to irregular, 39-54 x 48-65 µm. The spore wall consists of three smooth layers: one mucilaginous, short-lived, hyaline, outermost; one permanent, semirigid, hyaline, middle; and one laminate, hyaline to pastel yellow, innermost. Only the outermost spore wall layer of G. iranicum stains red in Melzer's reagent. In the field G. africanum was associated with roots of five plant species and an unrecognized shrub colonizing maritime sand dunes of two countries in Europe and two in Africa, and G. iranicum was associated with Triticum aestivum cultivated in southwestern Iran. In one-species cultures with Plantago lanceolata as the host plant G. africanum and G. iranicum formed arbuscular mycorrhizae. Phylogenetic analyses of partial SSU sequences of nrDNA placed the two new species in Glomus group A. Both species were distinctly separated from sequences of described Glomus species.