Dominikia duoreactiva sp. nov. and Dominikia difficilevidera sp. nov., two new species in the Glomeromycota

Summary

Two new species of arbuscular mycorrhizal fungi (AMF) of the recently erected genus Dominikia (Glomeromycota) are described based on their morphology and phylogenetic analyses of SSU–ITS–LSU sequences. The distinctive morphological characters of the first species, Dominikia duoreactiva sp. nov., is the formation of loose clusters with yellow-coloured, 30–70 µm diameter spores having a three-layered spore wall, of which layers 1 and 3 stain in Melzer’s reagent. The second species, Dominikia difficilevidera sp. nov., is distinguished by its hyaline, 31–45 µm diameter spores, which arise mainly singly and have a three-layered spore wall, of which layer 1 is thicker than the structural laminate layer 2, and layer 3 is flexible to semi-flexible.
Both species were originally associated with maritime dune plants; D. duoreactiva comes from the Giftun Island, Egypt, Africa, and D. difficilevidera from the Słowin´ ski National Park, Poland. Based on available data, we suggest D. duoreactiva occurs rarely in the world, and D. difficilevidera has a worldwide distribution, but it either occurs infrequently or has been overlooked or lost during spore extraction from soils of many sites because of its extremely small and hyaline spores. A method allowing the extraction of even the smallest spores of AMF, but observable under a dissecting microscope, is described.