Epiphyllous fungi from the Miocene of Clarkia, Idaho: reproductive structures

Abstract

The excellent preservation of fossil remains from the Miocene Clarkia locality in north central Idaho has provided for many investigations of the floral components, including their chemical and ultrastructural constituents and reconstructions of the paleoecosystem. Although fungal hyphae, reproductive structures, and spores were noted in a number of early studies, a concerted examination of the plant fossils indicated that epiphyllous fungi were rare, partially contradicting other evidence of a warm and humid environment. Recent collections indicate that epiphyllous fungi are in fact abundant at the locality. These include Phragmothyrites Edwards, previously noted in the literature, Stomiopeltites Alvin and Muir and a number of other fungi, predominantly in the Dothideales. The thyrothecia of Phragmothyrites were found mainly on Persea, Lithocarpus, Betula, and Magnolia and are uniquely characterized by concentric cell divisions. Stomiopeltites perithecia are non-radiate and ostiolate and were found on Betula, Smilax, and Zizyphoides. Other fungi present include non-radiate, non-ostiolate cleistothecia and hyphae similar to the Chaetomiaceae on the leaves of almost all plant genera. These findings support interpretations that the environment was warm and humid and also indicate that a thriving epiphyllous fungal community was present in this paleoecosystem.