Hysterangium atlanticum sp. nov., forms ectomycorrhizae with Coccoloba species (Polygonaceae) from the Atlantic rainforest of Northeastern Brazil

Abstract

Hysterangium basidiomata were collected associated with Coccoloba alnifolia and C. laevis (Polygonaceae), in the GuaribasBiological Reserve in the Atlantic rainforest, of northeastern Brazil during the rainy seasons of 2012?2013. Based on its uniquemorphological and molecular traits, this new taxon is described as Hysterangium atlanticum sp. nov. The most prominentmorphological characters that separate H. atlanticum from other close relatives are the large size of the basidiomata, the whiteperidium that rapidly turns greyish-orange to pale-red where bruised or exposed to air, and the ellipsoid to suboblong spores witha minutely verrucose surface. Molecular analyses of the LSU, SSU, atp6, and EF-1α markers were done. The analyses of theconcatenated atp6?EF-1α matrix confirmed the placement of the new species in the /hysterangium lineage. Moreover, at theinfra-generic level, Hysterangium atlanticum sp. nov. forms a sister cladewith Hysterangium sp. from Dicymbe forests located inneighboring Guyana. Moreover, the ectomycorrhizae (EcM) formed by H. atlanticum and roots of Coccoloba species wasconfirmed, based on identical ITS nrDNA sequences obtained from basidiomata and EcM root tissues. The main conspicuousfeatures of the EcM are: a well-developed plectenchimatous mantle, the ramarioid, abundant emanating hyphae with clamps andcovered with crystals, the presence of oleoacanthocystidia, and the whitish rhizomorphs. This is the first report of a Hysterangiumspecies forming EcM with native members of Coccoloba spp. in South America