AN EOCENE TAR SPOT ON A FOSSIL PALM AND ITS FUNGAL HYPERPARASITE

Two ascomycetes from the middle Eocene (48.7 million yr b.p.) Princeto n chert are described. Palaeoserenomyces allenbyensis gen. et sp, nov. consists of long, loculate stromata of distinctive columnar cells ben eath the epidermis of the extinct fan palm, Uhlia. allenbyensis. The s porogenous locules are empty but stromatal features and locule shape a re similar to extant Serenomyces, a genus in the Phyllachorales that f orms leaf spots on coryphoid palms. The locules of P. allenbyensis con tain circular structures that are interpreted as intralocular ascomata of a mycoparasite, Cryptodidymosphaerites princetonensis gen. et sp. nov. Two-celled ascospores in uniseriate rows are similar to the genus Didymosphaeria of the Melanommatales. These fossils are compared to D idymosphaeria conoidea, an extant mycoparasite of stromatic ascomycete s. The large number of exquisitely preserved fungal structures on taxo nomically defined hosts in the Princeton chert provides a unique oppor tunity for studying the diversity of microfungi in Tertiary paleoenvir onments.