Sieverdingia gen. nov., S. tortuosa comb. nov., and Diversispora peloponnesiaca sp. nov. in the Diversisporaceae (Glomeromycota)

Abstract

AbstractPhylogenetic analyses of 18S–ITS–28S nuc rDNA sequences indicated that the arbuscular mycorrhizal fungus originally described asGlomus tortuosumand later transferred to the genusCorymbiglomusrepresents a separate, previously unrecognized clade at the rank of genus in the family Diversisporaceae (order Diversisporales, phylum Glomeromycota). The analyses located the clade between clades representing the generaDesertisporaandRedeckera. Consequently, a new genus,Sieverdingia, was erected, withS. tortuosacomb. nov. The unique morphological feature ofS. tortuosais the formation of glomoid-like spores with a single-layered spore wall covered with a hyphal mantle. Importantly, the erection ofSieverdingiaclarified the definition ofCorymbiglomus, which currently consists of three species producing glomoid-like spores with one, three- to four-layered spore wall. The features of the innermost layer, which is hyaline, laminate, flexible to semi-flexible, indicate that it is a synapomorphy ofCorymbiglomus. The definitions ofCorymbiglomusand its species were emended. Moreover, the distribution ofS. tortuosaand the three species ofCorymbiglomuswas discussed based on own studies, literature data, and molecular sequences deposited in public databases. We concluded that the distribution ofS. tortuosaandC. globiferumknown in environmental studies based on their partial 28S nuc rDNA sequences only may be understated because the main molecular characteristics distinguishing these species reside outside the 28S region. Finally, we described a new species in the genusDiversisporaoriginating from Mediterranean dunes of the Peloponnese peninsula, Greece. The same phylogenetic analyses mentioned above indicated that the closest relative of the new species, producing dark-coloured spores, isD. clara, whose spores are creamy white at most.