A new family, pervetustaceae with a new genus, Pervetustus, and P. simplex sp. nov. (paraglomerales), and a new genus, Innospora with I. majewskii comb. nov. (Paraglomeraceae) in the Glomeromycotina

A new arbuscular mycorrhizal, Paraglomus-like, fungal species (Glomeromycotina) was found and propagated in single-species cultures established from spores coming from Oman, Greece, Tunisia, and New Caledonia. The hyaline spores of the fungus are small, 17-67 μm diam. when globose. Their spore wall consists of an evanescent, 1.0-2.3 μm thick, short-lived outer layer and a laminate, smooth, 3.8-7.3 μm thick inner layer, of which none shows amyloid or dextrinoid reaction in Melzer’s reagent. Mycorrhizal structures (arbuscules and hyphae without vesicles) of the fungus stained slightly in Trypan blue, thus like those of the formerly described Paraglomus spp., in which the histochemical feature has been recognized. However, in the phylogenies gained from analyses of nrDNA sequences, the fungus formed a distinct lineage in a basal position relative to and highly diverged from that with P. majewskii and that with the other Paraglomus spp. of known molecular phylogeny. Comparisons of similarity of sequences and the spore wall structure of the new fungus with those of P. majewskii and the other Paraglomus spp. and the positions of clades of the three taxa relative to those of the other taxa of the Glomeromycotina suggested transferring P. majewskii to a new genus in the Paraglomeraceae and describing the new fungus as a new species of a new genus in a new family of the order Paraglomerales.