Pseudoplagiostoma humilis sp. nov., a New Fungal Species Causing Shoot Blight and Dieback in Anacardium humile in Brazil.

The cajuzinho do cerrado (Anacardium humile-Anacardiaceae), a shrub species native to Brazil, is harvested for multiple uses in food and medicine. Members of a harvesting community, near the municipality of Bonito de Minas, Minas Gerais state, Brazil reported characteristic symptoms of shoot blight and dieback reducing pseudofruit and seed production by this plant. This study aimed to identify the etiological agent of this disease. Two fungal isolates were obtained from symptomatic leaf samples and morphologically and molecularly characterized. The fungus was identified, based on morphological analyses, as a probable new species of Pseudoplagiostoma. Phylogenetic analyses based on a combination of DNA sequence data (nuc rDNA ITS1-5.8S-ITS2 region, tef1-α and tub2), confirmed this hypothesis. The isolates obtained were allocated to a distinct, well-supported clade (IB = 0.99, ML = 100%), placed as a unique lineage here proposed as a new species named Pseudoplagiostoma humilis. The pathogenicity test confirmed that this new species was the causal agent of shoot blight and dieback on A. humile. This is the fourteenth Pseudoplagiostoma species reported in the world and the third in Brazil.