Abstract Detail

Paleobotany

Harper, Carla [1], Parrott, Joan [2], Upchurch, Garland [3], Krings, Michael [4].

Angiosperm wood-colonizing fungi (Ascomycota) from the Upper Cretaceous of New Mexico, USA.

Silicified wood is one of the most abundant plant fossils, and symptoms of fungal degradation are frequently encountered within these fossils; many fungus-infected woods contain also evidence of the causative agent in the form of hyphae, spores, etc. However, studies focusing on fungi and fungal activities in fossil wood are rare. Three principal rot types (i.e., white, brown, and soft rot) are known to occur in wood today, all inflicted by members of the Basidiomycota and, to a lesser extent, Ascomycota. Several wood taxa have been reported from the upper Campanian Jose Creek Member of the McRae Formation south-central New Mexico, USA, including numerous angiosperms; however, documented evidence of fungi and wood-fungus interactions has hitherto been absent. In this contribution we present on a small (<11 cm), degraded fragment of angiospermous wood float material from the McRae Formation. The specimen displays decay symptoms on the surface and is colonized internally by fungi. Regularly septate hyphae range from 1.8 to 8 µm in diameter and frequently produce right-angle branching; no clamp connections have been observed. The hyphae are present in all host cell types but are most prevalent in axial parenchyma and rays; hyphae appear to traverse via the pits. The most interesting fungal remain is well-preserved frequently branched catenulate hyphae (?or chains of conidia) up to 22 µm long, which occur in the vessels and rays. Individual hyphal segments are pyriform to club- or racquet-shaped and on average 8.7 µm long by 6.6 µm at the widest point. Other fungal structures are small spherules, possibly reproductive units or propagules, ~17 µm in diameter that fully occlude ray parenchyma. Thin-walled tyloses (33.5 to 68.5 µm) are present but it is impossible to determine if these structures are a result of fungal infection. While it is possible to map the colonization pathways and spatial distribution of the individual fungal remains in the wood, we are unable to determine at present whether the remains represent one or multiple species of fungi. Moreover, there is currently no way to tell whether the fungi represent wood-degraders or some transient saprotrophs. Nevertheless, documenting these fungal remains represents an important first step in our ability to ultimately understand the complex system of organismal interactions that existed in the McRae Formation paleoecosystem some 75 Ma ago.

1 - University Of Kansas, Ecology And Evolutionary Biology, 1200 Sunnyside Ave, Haworth Hall, Lawrence, KS, 66045, United States
2 - Texas State University, Department of Biology, San Marcos, TX, 78666, USA
3 - Texas State University, Department Of Biology, 601 University Drive, San Marcos, TX, 78666, United States
4 - Bayerische Staatssammlung Für Paläontologie Und Ge, Richard-Wagner Strasse 10, Munich, D-80333, Germany

Keywords:
fossil fungi
conidia
plant-fungus interaction
Campanian
wood fungus
symbiosis.

Presentation Type: Oral Paper
Session: 24, Late Mesozoic and Cenozoic Paleobotany
Location: 109/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 11:15 AM
Number: 24005
Abstract ID:423
Candidate for Awards:None