Acaulospora flavopapillosa, a new fungus in the Glomeromycetes from a coffee plantation in Peru, with an updated key for the identification of Acaulosporaceae species

A new fungus of the arbuscular-mycorrhiza forming Glomeromy-cetes was found in a coffee plantation in Palestina, located in the Amazonian region of San Martin State in Peru. The fungus was pro-pagated in bait cultures on Brachiaria brizantha, Medicago sativa and Sorghum vulgare as host plants. It forms typical acaulosporoid spores laterally on sporiferous saccule necks. The spores are brown-ish yellow to yellow brown, 125-160 mu m in diam and are crowded with papillae on their surface. The papillae are approximately 1 mu m wide as well as high. According to the color and surface structure of its spores, the fungus is here described under the epithet Acaulospora Piavopapillosa. Phylogenetically, the new fungus clusters in a well-separated clade within a group that comprises A. fragilissima, A. sac-cata, A. papillosa, A. morrowiae, A. delicata, A. rugosa, A. dilatata and A. longula. Also A. excavata and A. dilatata were found by con-comitant morphological and molecular phylogenetic analyses in San Martin State during this study: A. excavata in another coffee planta-tion, and A. dilatata in an inka nut plantation. An identification key for all species in the family Acaulosporaceae is updated in this study.