Cytochalasans produced by and their biological activities.

The recent description of the putative fungal pathogen of greenheart trees, (Xylariaceae, Ascomycota), prompted a study of its secondary metabolism to access its ability to produce cytochalasans in culture. Solid-state fermentation of the ex-type strain on rice medium resulted in the isolation of a series of 19,20-epoxidated cytochalasins by means of preparative high-performance liquid chromatography (HPLC). Nine out of 10 compounds could be assigned to previously described structures, with one compound being new to science after structural assignment via nuclear magnetic resonance (NMR) assisted by high-resolution mass spectrometry (HRMS).

Xylaria karyophthora: a new seed-inhabiting fungus of Greenheart from Guyana.

In 2010-2011, a Xylaria sp. was documented growing from seeds of both Chlorocardium rodiei and Chlorocardium venenosum, a commercially valuable timber in Guyana. We conducted extensive surveys in 2015-2016, where this Xylaria sp.

New species of Xerocomus (Boletales) from the Guiana Shield, with notes on their mycorrhizal status and fruiting occurrence.

Xerocomus cyaneibrunnescens, Xerocomus potaroensis, and Xerocomus parvogracilis (Boletales, Basidiomycota) are described as new species from the Pakaraima Mountains of Guyana, in the central Guiana Shield region. These boletes occur in neotropical forests dominated by ectomycorrhizal (ECM) trees in the genus Dicymbe (Fabaceae subfam. Caesalpinioideae).