Paleomycology of the Princeton Chert. III. Dictyosporic microfungi, Monodictysporites princetonensis gen. et sp. nov., associated with decayed rhizomes of an Eocene semi-aquatic fern

Abstract

This study builds on previous investigations of paleomycological diversity within permineralized plants of a significant Eocene paleobotanical locality, the Princeton Chert. The fungal body fossils described here occur in decayed rhizomes of the extinct semi-aquatic fern Dennstaedtiopsis aerenchymata. Fungi include vegetative hyphae throughout the plant tissue, as well as a dense assemblage of >100 dematiaceous spores. The spores occur in a discrete zone surrounding two extraneous rootlets of other plants, which penetrated the fern tissue post-mortem. Spores are obovoid and muriform, composed of 8–12 cells with constricted septa and produced from hyaline or slightly pigmented hyphae. The spores are morphologically similar to both asexual reproductive dictyospores of phylogenetically disparate microfungi attributed to the morphogenus Monodictys and perennating dictyochlamydospores that occur in the anamorph genus Phoma. In addition to expanding the early Eocene fossil record for Ascomycota, these specimens also provide new insight into the rapidity of initial phases of the fossilization process in this important paleobotanical locality.

• chlamydospore
• dictyochlamydospore
• dictyospore
• Monodictys
• Phoma

Acknowledgments

This research was supported in part by the Natural Sciences and Engineering Research Council of Canada ( NSERC PGS-D2-438186-2013 to AAK), the National Science Foundation ( EAR-0949947 to Thomas N. Taylor and Michael Krings; OPP-0943934 to Edith L. Taylor and Thomas N. Taylor) and the Department of Ecology and Evolutionary Biology, University of Kansas. Thanks also to Benjamin Sikes (Ecology & Evolutionary Biology, Kansas Biological Survey, Kansas University), Michael Krings (LMU, Munich) and Benjamin Bomfleur (Naturhistoriska Riksmuseet) for helpful discussion.