Cytospolides F–Q (6–17) and decytospolides A and B (18 and 19), 14 unusual nonanolide derivatives, were isolated fromCytosporasp., an endophyticfungusfrom Ilex canariensis. The structures were elucidated by means of detailed spectroscopic analysis, chemical interconversion, and X-ray single crystal diffraction. The solution- and solid-state conformers were compared by the combination of experimental