Carla J Harper1,2,3, Christopher Walker4,5, Andrew B Schwendemann6, Hans Kerp7, Michael Krings2,3,8. 1. Botany Department, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland. 2. SNSB-Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany. 3. Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Institute, University of Kansas, Lawrence, KS, USA. 4. Royal Botanic Garden Edinburgh, Edinburgh, UK. 5. School of Agriculture and Environment, University of Western Australia, Crawley, WA, Australia. 6. Department of Biology, Lander University, Greenwood, SC, USA. 7. Forschungsstelle für Paläobotanik am Geologisch-Paläontologischen Institut, Westfälische Wilhelms-Universität Münster, Münster, Germany. 8. Department für Geo- und Umweltwissenschaften, Paläontologie und Geobiologie, Ludwig-Maximilians-Universität, Munich, Germany.
Abstract
BACKGROUND AND AIMS: Structurally preserved arbuscular mycorrhizas from the Lower Devonian Rhynie chert represent core fossil evidence of the evolutionary history of mycorrhizal systems. Moreover, Rhynie chert fossils of glomeromycotan propagules suggest that this lineage of arbuscular fungi was morphologically diverse by the Early Devonian; however, only a small fraction of this diversity has been formally described and critically evaluated. METHODS: Thin sections, previously prepared by grinding wafers of chert from the Rhynie beds, were studied by transmitted light microscopy. Fossils corresponding to the description of Archaeospora spp. occurred in 29 slides, and were measured, photographed and compared with modern-day species in that genus. KEY RESULTS: Sessile propagules <85 µm in diameter, some still attached to a sporiferous saccule, were found in early land plant axes and the chert matrix; they developed, in a similar manner to extant Archaeospora, laterally or centrally within the saccule neck. Microscopic examination and comparison with extant fungi showed that, morphologically, the fossils share the characters used to circumscribe the genus Archaeospora (Glomeromycota; Archaeosporales; Archaeosporaceae). CONCLUSIONS: The fossils can be assigned with confidence to the extant family Archaeosporaceae, but because molecular analysis is necessary to place organisms in these taxa to present-day genera and species, they are placed in a newly proposed fossil taxon, Archaeosporites rhyniensis.
BACKGROUND AND AIMS: Structurally preserved arbuscular mycorrhizas from the Lower Devonian Rhynie chert represent core fossil evidence of the evolutionary history of mycorrhizal systems. Moreover, Rhynie chert fossils of glomeromycotan propagules suggest that this lineage of arbuscular fungi was morphologically diverse by the Early Devonian; however, only a small fraction of this diversity has been formally described and critically evaluated. METHODS: Thin sections, previously prepared by grinding wafers of chert from the Rhynie beds, were studied by transmitted light microscopy. Fossils corresponding to the description of Archaeospora spp. occurred in 29 slides, and were measured, photographed and compared with modern-day species in that genus. KEY RESULTS: Sessile propagules <85 µm in diameter, some still attached to a sporiferous saccule, were found in early land plant axes and the chert matrix; they developed, in a similar manner to extant Archaeospora, laterally or centrally within the saccule neck. Microscopic examination and comparison with extant fungi showed that, morphologically, the fossils share the characters used to circumscribe the genus Archaeospora (Glomeromycota; Archaeosporales; Archaeosporaceae). CONCLUSIONS: The fossils can be assigned with confidence to the extant family Archaeosporaceae, but because molecular analysis is necessary to place organisms in these taxa to present-day genera and species, they are placed in a newly proposed fossil taxon, Archaeosporites rhyniensis.
Authors: Stefan Hempel; Lars Götzenberger; Ingolf Kühn; Stefan G Michalski; Matthias C Rillig; Martin Zobel; Mari Moora Journal: Ecology Date: 2013-06 Impact factor: 5.499
Authors: Dirk Redecker; Arthur Schüssler; Herbert Stockinger; Sidney L Stürmer; Joseph B Morton; Christopher Walker Journal: Mycorrhiza Date: 2013-04-05 Impact factor: 3.387
Authors: Grace A Hoysted; Alison S Jacob; Jill Kowal; Philipp Giesemann; Martin I Bidartondo; Jeffrey G Duckett; Gerhard Gebauer; William R Rimington; Sebastian Schornack; Silvia Pressel; Katie J Field Journal: Plant Physiol Date: 2019-07-29 Impact factor: 8.340