Klymiuk, Ashley , Taylor, Thomas , Krings, Michael .
Anamorphic fungi from the Princeton Chert: new insights into paleomicrobial diversity.
The Lutetian (Eocene) Princeton Chert of southern British Columbia, Canada, is a succession of ~70 layers of silicified peat, interbedded with sub-bituminous coal. Within silicified layers, vascular plant remains are permineralized in three dimensions, often with a high degree of acuity, indicating minimal transport, and little degradation prior to preservation. The Chert has been characterized as an autochthonous mire assemblage, the floristic components of which have been intensively documented. By contrast, the fungal diversity has been less rigorously examined, excepting several fungi which had symbiotic or pathogenic relationships with plants. By thin-sectioning the chert, we increase our understanding of fungal diversity, and are able to establish the ontogeny of some reproductive structures. Ontogeny is pertinent to identification of hyphomycetous fungi, which frequently comprise the anamorphic stages of ascomycetes and basidiomycetes. Such microfungi reproduce via mitotic propagules, called conidia, and several distinct conidial morphologies are observed in Princeton chert. Of these, dematiaceous macroconidia have been linked to assimilative hyphae of a microfungus that occurs within the aerenchymatous cortex of the aquatic angiosperm Eorhiza arnoldii Robison et Person. These large, darkly pigmented conidia range from ~25 µm phragmospores to more mature scolecospores, 75-125 µm in length, with as many as 30-35 transverse septa. Conidiogenesis is holoblastic/monotretic and conidiogenous cells are 7 µm long, and 4 µm in diameter. They are subtended by 5 µm long metulae, or prophialides. Dispersal occurs by rhexolytic secession of conidia from the metulae. As a consequence, conidiogenous cells are incorporated as the bases of conidia, such that dispersed spores appear caudate. The conidiophores, which produce the metulae and conidiogenous cells, exhibit sympodial branching whereby new cells are formed through successive lateral branching subsequent to the production of a terminal conidium. Conidiophores are borne on hyaline, 3-4 µm diameter hyphae that lack clamp connections, congruent with an interpretation of this microfungus as a member of the Ascomycota. The assimilative mycelium is extensive throughout the cortex of Eorhiza, with conidia preferentially produced in channels between parenchyma chains. There is no observable host response associated with hyphal penetration of cell walls, and saprotrophic colonization of these roots indicates a period of subsurface residence prior to silicification. In addition to providing new data on the taphonomic succession preceding the exceptional preservation that has allowed the reconstruction of the anamorphic stage of an Eocene ascomycete, investigations of these microfungi expand our understanding of the microbial paleoecology of the Princeton Chert Lagerstätte.
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1 - University of Kansas, Ecology & Evolutionary Biology, Haworth Hall, 1200 Sunnyside Ave, Lawrence, KS, 66045, USA
2 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-2106, USA
3 - Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie, Ludwig- Maximilians-Universität, Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Straße 10, Munich, 80333, Germany
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Tuesday, July 10th, 2012
Time: 11:30 AM