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Acaulospora mendoncae (Acaulosporaceae), a new fungal species in the Glomeromycota from maritime sand dunes from southern Brazil

Abstract:

Spore morphology and phylogenetic analyses obtained from the SSU-ITS-LSU riboso-mal gene of an arbuscular mycorrhizal fungi (AMF) from maritime sand dunes in southern Brazil have indicated that it is an undescribed species. We describe this new species of AMF as Acaulos-pora mendoncae within the family Acaulosporaceae, order Diversisporales, class Glomeromycetes in the phylum Glomeromycota. Spores of A. mendoncae are mostly pale yellow, globose, 60– 120 µm (mean = 95 µm) in diameter, whose surface of the spore wall is ornamented with spiny projections up to 2 µm high. Spores are composed of a spore wall and two germinal walls. Spore wall is composed of a sloughing outer layer and a laminated rigid layer 3–4 µm thick. Germinal wall 1 is formed by two tightly adherent layers 1 µm thick each. Germinal wall 2 is formed by two layers: an outer beaded layer and an inner layer turning red purple in Melzer’s reagent. The phylo-genic trees reconstructed from ribosomal gene sequences placed A. mendoncae within the Acaulo-spora clade. Phylogenetically, A. mendoncae is closely related with A. aspera and A. spinosissima and pertain to a clade formed by species with distinct type of spore wall ornamentations. This species was found associated with Spartina ciliata (Poaceae) in frontal sand dunes at Joaquina Beach, Florianópolis, Brazil and this is the only location that this species has been reported up to date.