Gigaspora polymorphira, a new species of arbuscular mycorrhizal fungi (Glomeromycota) from Fanjingshan National Nature Reserve in China

Gigaspora polymorphira, a new arbuscular mycorrhizal fungal species, has been described based on morphological and phylogenetic analyses, which was isolated from rhizosphere soil of Phyllostachys heterocycla and Cunninghamia lanceolata in Fanjingshan National Nature Reserve, Guizhou province, China. Spores are white to orange yellow, irregular to rarely subglobose, 260–390×480–570 µm in diameter, and spore wall consisting of two layers (SWL1+SWL2): SWL1 hyaline to pale yellow, permanent, about 1 µm thick; SWL2 laminate and extremely rigid, yellow, 10–27 µm thick, staining dark red to red-brown in Melzer’s reagent. Germinal wall is permanent, membranous, about 1 µm thick and smooth. The sporogenous cell pale yellow, ovoid to clavate of 80–120×40–75 µm in diameter and have two sporogenous cell wall layers. Phylogenetic analysis of the sequences based on the partial small subunit (SSU), internal transcribed spacer region (ITS1-5.8S-ITS2), and the partial large subunit (LSU) indicated that Gi. polymorphira in the genus Gigaspora, separated from other described Gigaspora species. Phylogenetically, it forms a monophyletic clade next to Gigaspora margarita, which can be distinct distinguished from Gi. polymorphira by its shape of globose to subglobose and warts projects on GW. An updated key for the Gigaspora species worldwide is provide.