Glomus irregulare, a new arbuscular mycorrhizal fungus in the Glomeromycota

A new arbuscular mycorrhizal fungus (Glomeromycota) is described and illustrated. Glomus irregulare was found associated with different plants colonizing maritime sand dunes of Giftung Island, Egypt (Africa), Bornholm (Denmark), Greece, Poland, and Spain. This fungus produces spores aggregated inside roots or in the soil or (rarely) singly in the soil. Spores form blastically either (when aggregated) at the tip of or along dichotomously branched hyphae continuous with mycorrhizal extraradical hyphae or (when single) terminally from the unbranched extraradical hyphae. The hyaline to pale yellow spores are ovoid, oblong to irregular, 60-130 x 80-240 km, and may have deep wall depressions and apical cap-like swellings. The spore wall consists of two semi-permanent, hyaline outer layers and a hyaline to pale yellow, laminate innermost layer staining in Melzer's reagent. Glomus irregulare formed vesicular-arbuscular mycorrhizae in single-species cultures with Plantago lanceolata as the host plant. Phylogenetic analyses do not yet conclusively support the obvious morphological and biochemical differences between G. irregulare and G. intraradices, and the need to sequence other rDNA regions to further refine genetic relationships is suggested.