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

Abstract

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 × 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 × 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.

• arbuscular fungi
• Glomeromycota
• molecular phylogeny
• mycorrhizae
• new species

We thank Prof Zdzislaw Koszański, Department of Water Management, West Pomeranian University of Technology, Szczecin, for collecting the A. arenaria soil-root sample from Varna (Bulgaria). We also thank Dr P. Schreiner, Mycologia associate editor, and two anonymous reviewers for valuable comments. This study was supported in part by the Polish Committee of Scientific Researches, grants 2 PO4C 041 28 and 164/N-COST/2008/0, and the Hungarian Research Fund, OTKA K72776. A part of the study was conducted during the Experienced Researcher Fellowship of the Alexander von Humboldt Foundation awarded to G. M. Kovács.