Cetraspora auronigra, a new glomeromycete species from Ouro Preto (Minas Gerais, Brazil).

Abstract

Cetraspora auronigra, a new fungus of the Racocetraceae (Gigasporales, Glomeromycota), was found in a tropical mountainous forest and an adjacent ironstone outcrop located in the neighborhood of a mining area of Ouro Preto (Minas Gerais, southeastern Brazil). It forms bright yellow to golden-yellow, three-walled spores terminally on sporogenous cells and single, multiply lobed, hyaline to subhyaline germination shields on the outer surface of the inner (germinal) wall. The germinal wall stains dark purple to purple black in Melzer’s reagent. Spores of C. auronigra are most similar to the ‘apricot yellow’ to yellow brown spores of C. armeniaca, whose outer spore wall stains garnet red when exposed to Melzer’s reagent, while in C. auronigra this wall does not show any staining reaction. The name of the new fungus is dedicated to its spore colors, especially when exposed to Melzer’s reagent, and to the historical city Ouro Preto where the fungus was found in the rhizosphere of several annual and perennial plant species.