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Peter M. Letcher - One of the best experts on this subject based on the ideXlab platform.
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The growth response of some Chytridiomycota to temperatures commonly observed in the soil.
Mycological research, 2020Co-Authors: Frank H Gleason, Peter M. Letcher, Zoe Commandeur, Cho Eun Jeong, Peter A McgeeAbstract:Chytridiomycota were isolated into pure culture from cool temperate and warm semi-arid soils of eastern Australia. In pure culture these fungi responded variably to the range of temperatures commonly recorded in their environment. All members of the Blastocladiales, Spizellomycetales and Chytridiales grew in culture at temperatures up to 30 degrees C. Some isolates from the Blastocladiales and Spizellomycetales continued to grow at or above 37 degrees. Some isolates of the Chytridiales grew up to but not beyond 35 degrees. All isolates in the Chytridiales were able to resume growth at 20 degrees after brief exposure to temperatures higher than the maximum growth temperature, but were killed by exposure to higher temperatures for 7 d. Because in the natural soil habitat temperature may exceed the maximum for growth it may be a limiting factor that determines the distribution of chytrids in the soil.
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Some Chytridiomycota in soil recover from drying and high temperatures.
Mycological research, 2020Co-Authors: Frank H Gleason, Peter M. Letcher, Peter A McgeeAbstract:Rhizophlyctis rosea was found in 44% of 59 soil samples from national parks, urban reserves and gardens, and agricultural lands of eastern New South Wales, Australia. As some of the soils are periodically dry and hot, we examined possible mechanisms that enable survival in stressful environments such as agricultural lands. Air-dried thalli of R. rosea in soil and pure cultures of R. rosea, two isolates of Allomyces anomalus, one isolate of Catenaria sp., one of Catenophlyctis sp. and one of Spizellomyces sp. recovered following incubation at 90 degrees C for two days. Powellomyces sp. recovered following incubation at 80 degrees. Sporangia of all seven fungi shrank during air-drying, and immediately returned to turgidity when rehydrated. Some sporangia of R. rosea released zoospores immediately upon rehydration. These data indicate that some Chytridiomycota have resistant structures that enable survival through periodic drying and high summer temperatures typical of soils used for cropping. Eleven Chytridiomycota isolated from soil did not survive either drying or heat. Neither habitat of the fungus nor morphological type correlated with the capacity to tolerate drying and heat.
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Morphological, molecular, and ultrastructural characterization of Rozella rhizoclosmatii, a new species in Cryptomycota.
Fungal Biology, 2016Co-Authors: Peter M. Letcher, Joyce E. Longcore, C. Alisha Quandt, Domingos Da Silva Leite, Timothy Y. James, Martha J. PowellAbstract:Abstract Rozella is a genus of unwalled endoparasites of a variety of hosts including Oomycota (Stramenopiles), Blastocladiomycota and Chytridiomycota (Fungi), and one green alga ( Coleochaete , Chlorophyceae). It currently includes more than 20 formally described species, and no new species of Rozella have been described since 1987. We discovered a new Rozella species parasitizing Rhizoclosmatium globosum (Chytridiales, Chytridiomycota) and investigated its morphology, ultrastructure, and phylogenetic position. Herein named as Rozella rhizoclosmatii sp. nov., the organism induces hypertrophy of the host. Its zoospore is ultrastructurally similar to that of Rozella allomycis , although it has a unique zoospore ultrastructural feature, a lattice of perpendicular rods about the nucleus. The 18S rDNA molecular sequence of R. rhizoclosmatii is similar to that of the previously sequenced ‘ Rozella ex Rhizoclosmatium ’. This is the first study to inclusively characterize a new species of Rozella with morphological, ultrastructural and molecular data. As this is only the second Rozella species to be examined ultrastructurally, and because it is parasitic on a member of Chytridiomycota and not Blastocladiomycota, this research supports the conservative nature of zoospore ultrastructure to help define the genus.
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a new family and four new genera in rhizophydiales Chytridiomycota
Mycologia, 2015Co-Authors: Peter M. Letcher, Martha J. Powell, William J DavisAbstract:Many chytrid phylogenies contain lineages representing a lone taxon or a few organisms. One such lineage in recent molecular phylogenies of Rhizophydiales contained two marine chytrids, Rhizophydium littoreum and Rhizophydium aestuarii. To better understand the relationship between these organisms, we increased sampling such that the R. littoreum/R. aestuarii lineage included 10 strains of interest. To place this lineage in Rhizophydiales, we constructed a molecular phylogeny from partial nuc 28S rDNA D1–D3 domains (28S) of these and 80 additional strains in Rhizophydiales and examined thallus morphology and zoospore ultrastructure of our strains of interest. We also analyzed sequences of the nuc rDNA region encompassing the internal transcribed spacers 1 and 2, along with the 5.8S rDNA (ITS) of our 10 strains of interest to assess sequence similarity and phylogenetic placement of strains within the lineage. The 10 strains grouped together in three well supported clades: (i) Rhizophydium littoreum + Phlyc...
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hypothesized evolutionary trends in zoospore ultrastructural characters in chytridiales Chytridiomycota
Mycologia, 2014Co-Authors: Peter M. Letcher, Martha J. PowellAbstract:Chytridiales is an order of zoosporic fungi currently comprising species representing 19 genera. Although morphologically and genetically diverse, these taxa have in common a zoospore with a suite of ultrastructural characters unique among Chytridiomycota. However, multiple states have been reported for almost every character that defines the Chytridiales zoospore. Two zoospore types have been recognized, each corresponding to a family. Here we examine zoospore ultrastructure of 52 isolates in Chytridiales and assess states for six characters to hypothesize evolutionary trends, using parsimony ancestral state reconstruction for evolutionary analysis. Based on suites of character states, we describe four additional zoospore types in Chytridiales. Five of the six characters ([i] location of the nucleus, [ii] morphology of the kinetosome-associated structure, [iii] complexity of the microtubular root, [iv] microbody-lipid globule complex cisterna structure and [v] thickness of the flagellar plug) revealed an...
Peter A Mcgee - One of the best experts on this subject based on the ideXlab platform.
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Some Chytridiomycota in soil recover from drying and high temperatures.
Mycological research, 2020Co-Authors: Frank H Gleason, Peter M. Letcher, Peter A McgeeAbstract:Rhizophlyctis rosea was found in 44% of 59 soil samples from national parks, urban reserves and gardens, and agricultural lands of eastern New South Wales, Australia. As some of the soils are periodically dry and hot, we examined possible mechanisms that enable survival in stressful environments such as agricultural lands. Air-dried thalli of R. rosea in soil and pure cultures of R. rosea, two isolates of Allomyces anomalus, one isolate of Catenaria sp., one of Catenophlyctis sp. and one of Spizellomyces sp. recovered following incubation at 90 degrees C for two days. Powellomyces sp. recovered following incubation at 80 degrees. Sporangia of all seven fungi shrank during air-drying, and immediately returned to turgidity when rehydrated. Some sporangia of R. rosea released zoospores immediately upon rehydration. These data indicate that some Chytridiomycota have resistant structures that enable survival through periodic drying and high summer temperatures typical of soils used for cropping. Eleven Chytridiomycota isolated from soil did not survive either drying or heat. Neither habitat of the fungus nor morphological type correlated with the capacity to tolerate drying and heat.
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The growth response of some Chytridiomycota to temperatures commonly observed in the soil.
Mycological research, 2020Co-Authors: Frank H Gleason, Peter M. Letcher, Zoe Commandeur, Cho Eun Jeong, Peter A McgeeAbstract:Chytridiomycota were isolated into pure culture from cool temperate and warm semi-arid soils of eastern Australia. In pure culture these fungi responded variably to the range of temperatures commonly recorded in their environment. All members of the Blastocladiales, Spizellomycetales and Chytridiales grew in culture at temperatures up to 30 degrees C. Some isolates from the Blastocladiales and Spizellomycetales continued to grow at or above 37 degrees. Some isolates of the Chytridiales grew up to but not beyond 35 degrees. All isolates in the Chytridiales were able to resume growth at 20 degrees after brief exposure to temperatures higher than the maximum growth temperature, but were killed by exposure to higher temperatures for 7 d. Because in the natural soil habitat temperature may exceed the maximum for growth it may be a limiting factor that determines the distribution of chytrids in the soil.
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Access to organic and insoluble sources of phosphorus varies among soil Chytridiomycota
Archives of Microbiology, 2006Co-Authors: David J Midgley, Peter M. Letcher, Peter A McgeeAbstract:The sources of minerals accessed by fungi in the Chytridiomycota (chytrid) in soil are largely unknown. The ability of ten species of soil chytrids to use various sources of phosphorus was examined in vitro. While all grew on orthophosphate, fifty per cent of isolates grew on phytic acid, and one isolate grew on DNA as the sole source of phosphorus. All isolates solubilised and utilised CaHPO_4. Most isolates utilised hydroxyapatite when NH _4 ^+ was the nitrogen source. When ammonium was omitted, 50% of isolates solubilised hydroxyapatite. Many soil chytrids may utilise phosphomonoesters as the sole source of phosphorus, and access to DNA appears limited. We suggest that the capacity to use different sources of phosphorus may influence the diversity of chytrids found in Australian soils.
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can soil Chytridiomycota survive and grow in different osmotic potentials
Fungal Biology, 2006Co-Authors: Frank H Gleason, Peter M. Letcher, David J Midgley, Peter A McgeeAbstract:Abstract Twenty isolates from soil in the orders Spizellomycetales, Blastocladiales and Chytridiales (Chytridiomycota) grew on complex solid media supplemented with 10 g l−1 sodium chloride. In a synthetic liquid medium, 4.4 g l−1 sodium chloride strongly inhibited growth in three of the five isolates, possibly because of the effect of the ions or osmolarity of the solution. The maximum concentration for growth in synthetic liquid medium with different osmotic potentials using polyethylene glycol (PEG) varied considerably amongst the isolates. Three patterns of growth with increasing concentrations of PEG were evident among isolates within the genus Rhizophydium. Up to the concentration where growth ceased, the dry weight of each isolate either decreased, remained constant, or in one case, increased. Most of the fungi survived when incubated at room temperature for 7 d in complex liquid media supplemented with 35 g l−1 sodium chloride or 300 g l−1 PEG. These data indicate that soil Chytridiomycota can survive various osmotic potentials that may occur during the wetting and drying phases in soils.
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the growth response of some Chytridiomycota to temperatures commonly observed in the soil
Fungal Biology, 2005Co-Authors: Frank H Gleason, Peter M. Letcher, Zoe Commandeur, Cho Eun Jeong, Peter A McgeeAbstract:Chytridiomycota were isolated into pure culture from cool temperate and warm semi-arid soils of eastern Australia. In pure culture these fungi responded variably to the range of temperatures commonly recorded in their environment. All members of the Blastocladiales, Spizellomycetales and Chytridiales grew in culture at temperatures up to 30°C. Some isolates from the Blastocladiales and Spizellomycetales continued to grow at or above 37°. Some isolates of the Chytridiales grew up to but not beyond 35°. All isolates in the Chytridiales were able to resume growth at 20° after brief exposure to temperatures higher than the maximum growth temperature, but were killed by exposure to higher temperatures for 7 d. Because in the natural soil habitat temperature may exceed the maximum for growth it may be a limiting factor that determines the distribution of chytrids in the soil.
Frank H Gleason - One of the best experts on this subject based on the ideXlab platform.
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The growth response of some Chytridiomycota to temperatures commonly observed in the soil.
Mycological research, 2020Co-Authors: Frank H Gleason, Peter M. Letcher, Zoe Commandeur, Cho Eun Jeong, Peter A McgeeAbstract:Chytridiomycota were isolated into pure culture from cool temperate and warm semi-arid soils of eastern Australia. In pure culture these fungi responded variably to the range of temperatures commonly recorded in their environment. All members of the Blastocladiales, Spizellomycetales and Chytridiales grew in culture at temperatures up to 30 degrees C. Some isolates from the Blastocladiales and Spizellomycetales continued to grow at or above 37 degrees. Some isolates of the Chytridiales grew up to but not beyond 35 degrees. All isolates in the Chytridiales were able to resume growth at 20 degrees after brief exposure to temperatures higher than the maximum growth temperature, but were killed by exposure to higher temperatures for 7 d. Because in the natural soil habitat temperature may exceed the maximum for growth it may be a limiting factor that determines the distribution of chytrids in the soil.
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Some Chytridiomycota in soil recover from drying and high temperatures.
Mycological research, 2020Co-Authors: Frank H Gleason, Peter M. Letcher, Peter A McgeeAbstract:Rhizophlyctis rosea was found in 44% of 59 soil samples from national parks, urban reserves and gardens, and agricultural lands of eastern New South Wales, Australia. As some of the soils are periodically dry and hot, we examined possible mechanisms that enable survival in stressful environments such as agricultural lands. Air-dried thalli of R. rosea in soil and pure cultures of R. rosea, two isolates of Allomyces anomalus, one isolate of Catenaria sp., one of Catenophlyctis sp. and one of Spizellomyces sp. recovered following incubation at 90 degrees C for two days. Powellomyces sp. recovered following incubation at 80 degrees. Sporangia of all seven fungi shrank during air-drying, and immediately returned to turgidity when rehydrated. Some sporangia of R. rosea released zoospores immediately upon rehydration. These data indicate that some Chytridiomycota have resistant structures that enable survival through periodic drying and high summer temperatures typical of soils used for cropping. Eleven Chytridiomycota isolated from soil did not survive either drying or heat. Neither habitat of the fungus nor morphological type correlated with the capacity to tolerate drying and heat.
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What has happened to the “aquatic phycomycetes” (sensu Sparrow)? Part II: Shared properties of zoosporic true fungi and fungus-like microorganisms
Fungal Biology Reviews, 2017Co-Authors: Frank H Gleason, Osu Lilje, Lene LangeAbstract:Abstract Many species of zoosporic heterotrophic parasites, saprotrophs and mutualists in the Phyla Perkinsozoa (dinoflagellates), Oomycota, Hyphochytriomycota, Labyrinthulomycota and Phyomyxea share morphological characteristics with zoosporic true fungi especially with some of the Chytridiomycota and with fungus-like organisms in the Phyla Mesomycetozoea, Chytridiomycota and Aphelidae. These characteristics include chemotactic motile zoospores, zoosporangia which produce zoospores, thick walled resistant cysts, rhizoid-like structures, hyphal-like structures and cell walls surrounding the cells in several phases of their life cycle. These assemblages also inhabit both marine and freshwater ecosystems in which aquatic fungi and fungus-like organisms are found, have similar life cycles, grow on similar substrates, use similar infection strategies and infect some of the same host plants and animals. Many of these species were once included in the aquatic phycomycetes, an ecological assemblage of microorganisms but not a valid taxonomic group. Some of the shared characteristics are discussed in this review.
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preservation of Chytridiomycota in culture collections
Fungal Biology, 2007Co-Authors: Frank H Gleason, Sharon E Mozleystandridge, David Porter, Donna G Boyle, Alex D HyattAbstract:Methods for the preservation of fungi in the Chytridiomycota in culture collections are reviewed in this paper. The Chytridiomycota can be preserved with varying degrees of success using a number of different protocols including cryopreservation. The survival of fungi in the Chytridiomycota is sensitive to environmental factors such as lack of moisture, high temperatures, high osmotic potential, and availability of oxygen, all of which must be considered in designing preservation methods. The age of the culture at the initiation of preservation appears to be a particularly important determinant of viability. Recently, commonly used methods for preservation of other groups of fungi have been modified to improve the survival of the Chytridiomycota in culture collections. High rates of survival have been reported after cryopreservation of aerobic and anaerobic chytrids in 10 % glycerol or dimethyl sulphoxide as cryoprotectants. The rates of freezing and thawing must be carefully controlled in the methods for cryopreservation considered in this review. Further research on increasing long-term survival rates and morphological, physiological and genetic stability of Chytridiomycota at low temperatures is necessary.
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can soil Chytridiomycota survive and grow in different osmotic potentials
Fungal Biology, 2006Co-Authors: Frank H Gleason, Peter M. Letcher, David J Midgley, Peter A McgeeAbstract:Abstract Twenty isolates from soil in the orders Spizellomycetales, Blastocladiales and Chytridiales (Chytridiomycota) grew on complex solid media supplemented with 10 g l−1 sodium chloride. In a synthetic liquid medium, 4.4 g l−1 sodium chloride strongly inhibited growth in three of the five isolates, possibly because of the effect of the ions or osmolarity of the solution. The maximum concentration for growth in synthetic liquid medium with different osmotic potentials using polyethylene glycol (PEG) varied considerably amongst the isolates. Three patterns of growth with increasing concentrations of PEG were evident among isolates within the genus Rhizophydium. Up to the concentration where growth ceased, the dry weight of each isolate either decreased, remained constant, or in one case, increased. Most of the fungi survived when incubated at room temperature for 7 d in complex liquid media supplemented with 35 g l−1 sodium chloride or 300 g l−1 PEG. These data indicate that soil Chytridiomycota can survive various osmotic potentials that may occur during the wetting and drying phases in soils.
Joyce E. Longcore - One of the best experts on this subject based on the ideXlab platform.
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A New Chytridiomycete Fungus Intermixed with Crustacean Resting Eggs in a 407-Million-Year-Old Continental Freshwater Environment
PLOS ONE, 2016Co-Authors: Christine Strullu-derrien, Joyce E. Longcore, Tomasz Góral, Jørgen Olesen, Paul Kenrick, Gregory D. EdgecombeAbstract:: The 407-million-year-old Rhynie Chert (Scotland) contains the most intact fossilised remains of an early land-based ecosystem including plants, arthropods, fungi and other microorganisms. Although most studies have focused on the terrestrial component, fossilised freshwater environments provide critical insights into fungal-algal interactions and the earliest continental branchiopod crustaceans. Here we report interactions between an enigmatic organism and an exquisitely preserved fungus. The fungal reproductive structures are intermixed with exceptionally well-preserved globular spiny structures interpreted as branchiopod resting eggs. Confocal laser scanning microscopy enabled us to reconstruct the fungus and its possible mode of nutrition, the affinity of the resting eggs, and their spatial associations. The new fungus (Cultoraquaticus trewini gen. et sp. nov) is attributed to Chytridiomycota based on its size, consistent formation of papillae, and the presence of an internal rhizoidal system. It is the most pristine fossil Chytridiomycota known, especially in terms of rhizoidal development and closely resembles living species in the Rhizophydiales. The spiny resting eggs are attributed to the crustacean Lepidocaris rhyniensis, dating branchiopod adaptation to life in ephemeral pools to the Early Devonian. The new fungal interaction suggests that, as in modern freshwater environments, chytrids were important to the mobilisation of nutrients in early aquatic foodwebs.
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Morphological, molecular, and ultrastructural characterization of Rozella rhizoclosmatii, a new species in Cryptomycota.
Fungal Biology, 2016Co-Authors: Peter M. Letcher, Joyce E. Longcore, C. Alisha Quandt, Domingos Da Silva Leite, Timothy Y. James, Martha J. PowellAbstract:Abstract Rozella is a genus of unwalled endoparasites of a variety of hosts including Oomycota (Stramenopiles), Blastocladiomycota and Chytridiomycota (Fungi), and one green alga ( Coleochaete , Chlorophyceae). It currently includes more than 20 formally described species, and no new species of Rozella have been described since 1987. We discovered a new Rozella species parasitizing Rhizoclosmatium globosum (Chytridiales, Chytridiomycota) and investigated its morphology, ultrastructure, and phylogenetic position. Herein named as Rozella rhizoclosmatii sp. nov., the organism induces hypertrophy of the host. Its zoospore is ultrastructurally similar to that of Rozella allomycis , although it has a unique zoospore ultrastructural feature, a lattice of perpendicular rods about the nucleus. The 18S rDNA molecular sequence of R. rhizoclosmatii is similar to that of the previously sequenced ‘ Rozella ex Rhizoclosmatium ’. This is the first study to inclusively characterize a new species of Rozella with morphological, ultrastructural and molecular data. As this is only the second Rozella species to be examined ultrastructurally, and because it is parasitic on a member of Chytridiomycota and not Blastocladiomycota, this research supports the conservative nature of zoospore ultrastructure to help define the genus.
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Operculomyces is a new genus in the order Rhizophydiales
Mycologia, 2011Co-Authors: Martha J. Powell, Peter M. Letcher, Joyce E. LongcoreAbstract:In recent years molecular phylogenies based on analyses of rDNA sequences have advanced knowledge of the Chytridiomycota, but much alpha taxonomic work remains. We have discovered an operculate chytrid that molecular phylogenies placed in the Rhizophydiales, an order that currently contains a single operculate species, the rest having inoperculate zoospore release. Because descriptions of genera in the Chytridiomycota now rely on transmission electron microscopic features of the zoospore as well as molecular evidence we studied the zoospore ultrastructure of the isolate to confirm its placement in the Rhizophydiales and to evaluate it as a new genus. Its suite of ultrastructural characters confirmed its placement within the Rhizophydiales, and its J-shaped, multilayered spur and the position of the nonflagellate centriole at a slight angle to the kinetosome make it unique within the Rhizophydiales, thus supporting molecular evidence indicating that the isolate represents a new genus. Herein we describe zo...
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An unusual microfungus in a fungal spore from the Lower Devonian Rhynie chert
Palaeontology, 2010Co-Authors: Michael Krings, Joyce E. Longcore, Nora Dotzler, Thomas N TaylorAbstract:Abstract: A new fossil microfungus, Kryphiomyces catenulatus gen. et sp. nov., occurs as an endobiotic mycelial thallus in a large spore of a glomeromycotan fungus from the Lower Devonian Rhynie chert. The thallus consists of branched (?pseudo-)septate hyphae with numerous catenulate swellings. Some hyphal tips produce spherical reproductive structures or propagules. Hyphal morphology in K. catenulatus is reminiscent of that in certain extant HyphoChytridiomycota, Chytridiomycota, and even Ascomycota, but specific diagnostic features that allow assignment of the fossil to modern groups are absent. The discovery of this interfungal association broadens our knowledge about the diversity of microfungi and their intricate associations in early continental ecosystems.
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cladochytriales a new order in Chytridiomycota
Fungal Biology, 2009Co-Authors: Sharon E Mozleystandridge, Joyce E. Longcore, David Porter, Peter M. Letcher, Rabern D SimmonsAbstract:Recently, molecular and ultrastructural analyses have resulted in revised phylogenetic hypotheses in the phylum Chytridiomycota. The order Chytridiales, once considered monophyletic, has been subdivided into several new orders. However, the most recent analyses indicate that the emended Chytridiales is also polyphyletic. One monophyletic lineage in Chytridiales includes Cladochytrium, Nowakowskiella, and five other genera. Many of the chytrids in this clade have often been observed growing on decaying plant tissue and other cellulosic substrates from aquatic habitats and moist soils. In this study we analysed combined nu-rRNA gene sequences (partial SSU and LSU) of 30 isolates from North American aquatic and soil samples. Based on molecular monophyly and zoospore ultrastructure, we designate this clade as a new order, Cladochytriales, which includes four families: Cladochytriaceae, Nowakowskiellaceae, Septochytriaceae fam. nov., and Endochytriaceae.
Michael Krings - One of the best experts on this subject based on the ideXlab platform.
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Systematic palaeontology (Palaeobotany) A microfungal assemblage in Lepidodendron from the Upper Visean (Carboniferous) of central France
2020Co-Authors: Michael Krings, Nora Dotzler, Thomas N Taylor, Jean GaltierAbstract:A diverse assemblage of microfungi and fungi-like microorganisms, composed of several types of hyphae, putative reproductive structures (sporangia), and a variety of spores, occurs in permineralized Lepidodendron xylem and periderm from the Upper Visean of central France. Some of the remains can be attributed to the Chytridiomycota and Peronosporomycetes (Oomycota) with some degree of confidence. We suggest that this assemblage represents a community of saprotrophic organisms that colonized the tissues post mortem and participated in the decay process. The permineralized Lepidodendron tissues from France offer a rare direct insight into the diversity of microfungi and fungi-like organisms in a Carboniferous terrestrial paleoecosystem. To cite this article:
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A microfungal assemblage in Lepidodendron from the Upper Visean (Carboniferous) of central France
Comptes Rendus Palevol, 2020Co-Authors: Michael Krings, Nora Dotzler, Thomas N Taylor, Jean GaltierAbstract:International audienceA diverse assemblage of microfungi and fungi-like microorganisms, composed of several types of hyphae, putative reproductive structures (sporangia), and a variety of spores, occurs in permineralized Lepidodendron xylem and periderm from the Upper Visean of central France. Some of the remains can be attributed to the Chytridiomycota and Peronosporomycetes (Oomycota) with some degree of confidence. We suggest that this assemblage represents a community of saprotrophic organisms that colonized the tissues post mortem and participated in the decay process. The permineralized Lepidodendron tissues from France offer a rare direct insight into the diversity of microfungi and fungi-like organisms in a Carboniferous terrestrial paleoecosystem
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a new species of perexiflasca enigmatic microfossils with suggested affinities to Chytridiomycota fungi from the lower devonian rhynie and windyfield cherts
Geobios, 2019Co-Authors: Michael Krings, Carla J HarperAbstract:Abstract Perexiflasca tayloriana, a widespread microfossil in the Lower Devonian Rhynie chert from Scotland, consists of a thin-walled cavity surrounded by a prominent sheath. A single tube extends from the cavity to the surface. Specimens occur singly or aggregated in decaying plant tissue and on fungi. Perexiflasca tayloriana has been attributed to the Chytridiomycota and interpreted as a sheathed zoosporangium. Here we report Perexiflasca ventricosa nov. sp., a fossil from the nearby coeval Windyfield chert that corresponds to P. tayloriana in basic organization, but possesses a distinctly larger cavity and wider tube, while the sheath is proportionally less extensive. The diagnosis and description of P. tayloriana are emended. The similarities between P. tayloriana and P. ventricosa nov. sp. render attribution also of P. ventricosa nov. sp. to the Chytridiomycota a plausible option, but features of sufficient clarity to permit reliable assignment are absent. Perexiflasca ventricosa nov. sp. expands the inventory of morphologically distinct microbial fossils from the Rhynie and Windyfield cherts.
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Early Devonian (~410 mya) microfossils resembling Characiopsis (Tribophyceae) and Characium (Chlorophyceae).
Journal of Phycology, 2017Co-Authors: Michael Krings, Carla J Harper, Edith L. Taylor, Hans KerpAbstract:Unusual microfossils that occurred associated with fungal spores in the Lower Devonian (similar to 410mya) Windyfield chert from Scotland were composed of a narrow stipe (2.5-9m long) to which was attached an obovoid or elongate drop-shaped cell up to 14m long;a basal attachment pad was present in several specimens. The fossils were strikingly similar morphologically to certain present-day unicellular freshwater Tribophyceae and Chlorophyceae, but affinities to the fungal phylum Chytridiomycota also cannot be ruled out. This discovery adds to the inventory of distinctive microbial morphologies in the early non-marine paleoecosystems.
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an enigmatic fossil fungus from the 410 ma rhynie chert that resembles macrochytrium Chytridiomycota and blastocladiella blastocladiomycota
Mycologia, 2016Co-Authors: Michael Krings, Thomas N Taylor, Helmut MartinAbstract:Litter layers in the Lower Devonian (~ 410 Ma) Rhynie chert were inhabited by a wide variety of saprotrophic fungi, however, only a few of these organisms have been described formally. A new microfungus, Trewinomyces annulifer gen. et sp. nov., occurs as tufts on decaying land plant axes from the Rhynie chert. The fungus consists of an intramatrical rhizoidal system and an erect extramatrical hypha (stalk) that bears a single, terminal sporangium. One or two successive rings often are present in the stalk immediately below the sporangium base. Overall morphology of T. annulifer resembles the extant genera Macrochytrium (Chytridiomycota) and Blastocladiella (Blastocladiomycota). However, the rhizoids are septate or pseudoseptate, a feature not known in extant zoosporic fungi, and thus render the systematic affinities of T. annulifer unresolved. Trewinomyces annulifer offers a rare view of the morphology of a distinctive Early Devonian saprotrophic microfungus.