The Fossil Record of the Peronosporomycetes (Oomycota)

This is the publisher's version, which is being shared with permission. The original may be found at the following link: http://dx.doi.org/10.3852/10-278Evidence of fossil Peronosporomycetes has been slow to accumulate. In this review various fossils historically assigned to the Peronosporomycetes are discussed briefly and an explanation is provided as to why the fossil record of this group has remained inconsistent. In recent years there have been several new reports of fossil peronosporomycetes based on structurally preserved oogonium-antheridium complexes from Devonian and Carboniferous rocks that demonstrate the existence of these organisms as fossils and refute the long-standing assumption that they are too delicate to be preserved. Among these are several types characterized by oogonial surface ornamentation patterns not seen in any modern members of the group. To date at least three groups of fossil vascular plants (i.e. lycophytes, ferns and seed ferns) are known to host peronosporomycetes as endophytes; however only one form has been identified as a parasite

Fossil evidence of the zygomycetous fungi

Molecular clock data indicate that the first zygomycetous fungi occurred on Earth during the Precambrian, however, fossil evidence of these organisms has been slow to accumulate. In this paper, the fossil record of the zygomycetous fungi is compiled, with a focus on structurally preserved Carboniferous and Triassic fossils interpreted as zygosporangium-gametangia complexes and resembling those of modern Endogonales. Enigmatic microfossils from the Precambrian to Cenozoic that have variously been interpreted as, or compared to, zygomycetous fungi are also discussed. Among these, the spherical structures collectively termed 'sporocarps' are especially interesting because of their complex investments and abundance in certain Carboniferous and Triassic rocks. Circumstantial evidence suggests that at least some 'sporocarp' types represent mantled zygosporangia. Zygomycetous fungi probably were an important element in terrestrial paleoecosystems at least by the Carboniferous.Financial support for part of the research referred to here was provided by the National Science Foundation (EAR-0949947 to TNT and MK) and the Alexander von Humboldt-Foundation (V-3.FLFDEU/ 1064359 to MK)

Fossil evidence of the zygomycetous fungi

Molecular clock data indicate that the first zygomycetous fungi occurred on Earth during the Precambrian, however, fossil evidence of these organisms has been slow to accumulate. In this paper, the fossil record of the zygomycetous fungi is compiled, with a focus on structurally preserved Carboniferous and Triassic fossils interpreted as zygosporangium-gametangia complexes and resembling those of modern Endogonales. Enigmatic microfossils from the Precambrian to Cenozoic that have variously been interpreted as, or compared to, zygomycetous fungi are also discussed. Among these, the spherical structures collectively termed 'sporocarps' are especially interesting because of their complex investments and abundance in certain Carboniferous and Triassic rocks. Circumstantial evidence suggests that at least some 'sporocarp' types represent mantled zygosporangia. Zygomycetous fungi probably were an important element in terrestrial paleoecosystems at least by the Carboniferous.Financial support for part of the research referred to here was provided by the National Science Foundation (EAR-0949947 to TNT and MK) and the Alexander von Humboldt-Foundation (V-3.FLFDEU/ 1064359 to MK)

Oldest Fossil Basidiomycete Clamp Connections

This is the publisher's version, which is being shared with permission. The original version is available from: http://dx.doi.org/10.1007/s10267-010-0065-4A rachis of the fossil filicalean fern Botryopteris antiqua containing abundant septate hyphae with clamp connections is preserved in a late Visean (Mississippian; *330 Ma) chert from Esnost (Autun Basin) in central France. Largely unbranched tubular hyphae pass from cell to cell, but may sometimes produce a branch from a clamp connection. Other clamp-bearing hyphae occur clustered in individual cells or small groups of adjacent host cells. These hyphae may be tubular, catenulate with numerous hyphal swellings, or they may display a combination of both. The Visean hyphae with clamp connections predate Palaeancistrus martinii, the heretofore oldest direct fossil evidence of Basidiomycota, by some 25 Ma

Fossil fungi with suggested affinities to the Endogonaceae from the Middle Triassic of Antarctica

This is the publisher's version, also available from http://www.mycologia.org/content/104/4/835.Documented fossil evidence of zygomycetous fungi is rare. A conspicuous fungal fossil, Jimwhitea circumtecta gen. et sp. nov., occurs in permineralized peat from the Middle Triassic of Antarctica. The fossil is interpreted as a mantled zygosporangium that buds from a macrogametangium subtended by a sac-like macrosuspensor. The macrogametangium is united at its tip with a microgametangium which is subtended by a micro-suspensor. This configuration is strikingly similar to the zygosporangium-gametangia complexes seen in certain modern Endogonaceae. Co-occurring with J. circumtecta are isolated propagules closely resembling the zygosporangium of J. circumtecta and a portion of a sporocarp containing zygosporangia embedded in a gleba. Several of the sporangia are borne on ovoid or elongate structures, which we interpret as gametangia. These fossils offer an exceptionally detailed view of the morphology and reproductive biology of early Mesozoic zygomycetes

Frankbaronia velata nov. sp., a putative peronosporomycete oogonium containing multiple oospores from the Lower Devonian Rhynie chert

Spherical to pyriform microfossils containing multiple smooth-walled spherules from the Lower Devonian Rhynie chert are described as oogonia of a new fossil peronosporomycete based on congruencies in basic morphology to the polyoosporous oogonia of certain extant Saprolegniales. Because the new fossils also resemble Frankbaronia polyspora, a putative peronosporomycete described previously from the Rhynie chert, they are assigned to the fossil genus Frankbaronia and formally proposed as a new species, F. velata. Surrounding the oogonium is a conspicuous sheath of consolidated mucilage, produced and secreted by the oogonium during development. The discovery of F. velata adds to our understanding of the microbial diversity in early terrestrial ecosystems, and contributes to the documentation of the evolutionary history of the Peronosporomycetes.Kugelige bis tropfenförmige, glattwandige kugelige Strukturen in großer Zahl enthaltende Mikrofossilien aus dem unterdevonischen Rhynie Chert werden als Oogonien eines neuen fossilen Peronosporomyzeten beschrieben, da sie den polyoosporen Oogonien einiger heutiger Saprolegniales morphologisch sehr ähnlich sind. Da die Fossilien auch mit Frankbaronia polyspora, einem bereits früher aus dem Rhynie Chert beschriebenen vermeintlichen Peronosporomyzeten, gut vergleichbar sind, werden sie ebenfalls in die Gattung Frankbaronia gestellt und als neue Art, F. velata, eingeführt. Die Oogonien sind von einer auffälligen Hülle aus konsolidiertem Schleim umgeben, welcher vom sich entwickelnden Oogonium produziert und sekretiert wurde. Frankbaronia velata trägt zu einem besseren Verständnis der mikrobiellen Diversität in frühen terrestrischen Ökosystemen sowie zur Dokumentation der Evolutionsgeschichte der Peronosporomycetes bei