Abstract
Asci of Massarina ramunculicola are bitunicate with an ocular chamber and apical differentiation of the wall. Ascospores possess an exosporial mucilaginous sheath which contains a fibrillar component. Prior to ascospore release the fibrillar material of the sheath penetrates the delimiting membrane at the ascospore poles to form a polar cap. This structure is unique among the species of Massarina that have been examined at the ultrastructural level.