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A taxonomic summary of Chytriomyces (Chytridiomycota)
Abstract
The genus Chytriomyces was established by Karling to accommodate two similar species, C. hyalinus and C. aureus. The generic concept of Chytriomyces has become altered substantially from its original circumscription, mainly through attrition of utilizable generic characters, to its present simpler, yet less precise definition. Remaining reliable characters that help define Chytriomyces are: an epibiotic and operculate sporangium, and epibiotic resting spores. For each of the 34 species of Chytriomyces, a taxonomic description and ecological/distributional data are presented. The type of Chytriomyces is designated herein, and terminology pertinent to morphological features is discussed. A taxonomic key based on readily observable morphological character states, and figures derived primarily from the original literature, are presented to assist in species identification.
... 34, 40, 43, 58;Willoughby 1959: pl. 5, fig. 2;Letcher & Powell 2002: fig. 8), Phlyctochytrium planicorne G.F. Atk. ...
Palaeonitella cranii is the only known charophyte from the Lower Devonian Rhynie chert. Thalli consist of a main axis with whorls of branchlets, and rhizoids with bulbils. The above-ground parts of this alga are known to have been colonized by a variety of probably parasitic fungi; however, virtually nothing is on record about fungal associations with the rhizoids and bulbils. Here, we describe four different fungal morphotypes as colonizers of bulbils of P. cranii. Morphotypes 1 and 2 are both characterized by epibiotic or interbiotic sporangia and endobiotic apophysate rhizoidal systems. Morphotype 3 occurs in the form of long stalks terminating in pinhead-like inflations, and club-shaped endobiotic axes producing rhizoids distally, whereas morphotype 4 consists of sterile, several-times forked, hypha-like elements. A three-dimensional meshwork of interwoven rhizoids of the colonizers is found in the lumen of several bulbils, indicating that the hosts were viable and crammed with starch grains at the time of colonization. The bulbil-colonizing fungi all differ from the fungi associated with the axes and branchlets of P. cranii, which suggests organ-specific host colonization. Morpho-types 1 and 2 are probably chytrids (Chytridiomycota), while morphotype 3 could be a member of the Mucoromycota; however, affinities to other lineages of fungi cannot be ruled out. This discovery expands the inventory of fungal associations with P. cranii, and provides new data that can be used in considerations on the importance of microorganisms for other aquatic life in the Rhynie ecosystem.
... However, Willoughby's drawing and accompanying text do not include depictions of the rhizoidal system and release mechanism. Resting spores of L. poculatus described by Letcher and Powell (2002) vary from B. amictus. ...
Glomeromycotan spores from the Early Devonian Rhynie chert frequently contain evidence of colonization by other fungi. However, relatively few of these relationships have been described and evaluated. Brijax amictus gen. et sp. nov., a probable chytrid (Chytridiomycota) associated with certain thick-walled archeosporalean acaulospores from the Rhynie chert, develops largely within the host spore wall. Thalli are eucarpic, monocentric, 16.5–40(− 50) μm high, and consist of an inoperculate sporangium (zoosporangium or resting spore stage) located in the outer, ephemeral spore wall component, and a rhizoidal system that extends into the persistent spore wall. Sporangia that, at maturity, are completely surrounded by the host spore wall develop a prominent discharge tube, whereas ones not covered by the host wall have simple openings or pores. Thallus morphology resembles certain present-day species of Rhizophydium (Rhizophydiales) and Phlyctochytrium (Chytridiales); however, the systematic affinities of B. amictus remain unresolved. This discovery contributes to the understanding of the various levels of interfungal relationship that existed in early terrestrial ecosystems.
... "cosmarii"). These fungi produce zoosporangia containing zoospores or resting spores enveloped in a prominent sheath (also termed a halo, coronum, hull, or gelatinous covering; see Lind 1905;Couch 1932;Sparrow 1933;Hanson 1945;Canter 1954;Karling 1966;Letcher andPowell 2002, 2012) that closely resemble N. rothwellii ( fig. 4), thus suggesting that the affinities of the fossils lie with the Chytridiomycota. Nimbosphaera rothwellii shares morphological similarities with the aforementioned chytrids in virtually all aspects, including a prominent sheath, central spheroidal vesicle (sporangium), and numerous internal spherules (zoospores). ...
Premise of research. Microbial mats in the Lower Devonian Windyfield chert comprise diverse communities of organisms; however, little information on the various life forms that occur in these formations is available. A recently cut and thin-sectioned block of Windyfield chert contains an extensive microbial mat that formed among an in situ stand of charophytes.
Methodology. Thin sections of the chert were screened systematically at high magnification (×400 and ×1000) in transmitted light. Images of fossils were captured digitally and processed in Adobe Photoshop CS6.
Pivotal results. The microbial mat contains 15 specimens of Nimbosphaera rothwellii nov. gen. et sp., a hitherto unknown microfossil composed of a vesicle containing spheroidal bodies and enveloped in a prominent sheath. Extending from some vesicles are a bulbous appendage and putative rhizoids. The fossils resemble the sheathed zoosporangia of certain extant chytrids, in particular Rhizophydium coronum, thus suggesting affinities of N. rothwellii to Chytridiomycota.
Conclusions. This discovery expands our knowledge of the diversity of organisms that thrived in early nonmarine microbial mats and provides further evidence that microbial mat frameworks served as a conservation trap for delicate microbial life in the Rhynie and Windyfield settings.
... 843 Rhizophydium mycetophagum was found in mycelia of 844 Choanephorella cucurbitarum (Mucoromycota), whereas 845 Chytriomyces mortierellae parasitizes Mortierella sp. 846 (Mortierellomycota) ( Letcher and Powell 2002). Species of 847 Phlyctochytrium have been isolated from vesicular-arbus-848 cular mycorrhizal fungi (Glomeromycotina) (Daniels and 849 Menge 1980;Hajek et al. 2013). ...
Fungicolous fungi are a very large, diverse, ecological and trophic group of organisms that are associated with other fungi. This association occurs with species of different lineages across the fungal kingdom. They are recognized as symbionts, mycoparasites, saprotrophs, and even neutrals. Wherever fungi have been found, fungicolous taxa have also been found. Homogeneous environments favour the development of highly adapted and coevolved fungicolous species, which could have led to host-specificity aspects. As a primary consumer, fungicolous fungi decrease the turnaround time of certain nutrients in food webs, due to their special often-rapid life cycles. They may also significantly affect population dynamics and population sizes of their hosts in aquatic or terrestrial ecosystems. As mycoparasites of pathogenic fungi, some fungicolous fungi have been explored as biocontrol agents. They may also cause serious diseases of cultivated edible and medicinal mushrooms, decreasing both yield and quality. Fungicolous fungi could be used as model organisms that may help determine better understanding of species interactions, fungal evolution and divergence, and fungicolous mechanisms. This review summarizes our current understanding of fungicolous fungi, with a particular focus on the terminology, diversity, global distribution, and interaction with their hosts. We also provide a checklist including 1552 fungicolous fungal taxa so far recorded following the updated classification schemes. There is a need for further investigations on this ecologically important group of fungi to better understand their biology, ecological aspects, origin and divergence, host-specificity and application in biocontrol. Accurate identification of these fungi as pathogens and their significance in quarantine purposes on the mushroom industry need further evaluations so that efficient control measures can be developed for better disease management purposes.
... It is possible that these chytrids were present in the pond water from which these tadpoles were collected, and that they somehow persisted on the tadpole mouthparts despite our following established procedures to clean them by dragging through sterile agar several times (Longcore et al., 1999). Although studies of the morphology and systematics of U. harderi, Chytriomyces, and H. curvatum can be found in the literature, little appears to be known about the life history of these species (Ustinova et al., 2000;Forget et al., 2002;Letcher and Powell, 2002;Powell et al., 2015). Many chytrids have similar, uninformative morphological features (James et al., 2000), and what appear to be successful isolations may not represent Batrachochytrium species. ...
Chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium
dendrobatidis (Bd), has caused amphibian population declines worldwide. Bd was first described in the
1990s and there are still geographic gaps in the genetic analysis of this globally distributed pathogen.
Relatively few genetic studies have focused on regions where Bd exhibits low virulence, potentially
creating a bias in our current knowledge of the pathogen's genetic diversity. Disease-associated declines
have not been recorded in Texas (USA), yet Bd has been detected on amphibians in the state. These strains
have not been isolated and characterized genetically; therefore, we isolated, cultured, and genotyped Bd
from central Texas and compared isolates to a panel of previously genotyped strains distributed across
the Western Hemisphere. We also isolated other chytrids from east Texas not known to infect amphibians.
To identify larval amphibian hosts, we sequenced part of the COI gene. Among 37 Bd isolates
from Texas, we detected 19 unique multi-locus genotypes, but found no genetic structure associated with
host species, Texas localities, or across North America. Isolates from central Texas exhibit high diversity
and genetically cluster with BdGPL isolates from the western U.S. that have caused amphibian population
declines. This study genetically characterizes isolates of Bd from the south central U.S. and adds to the
global knowledge of Bd genotypes.
... Th e order Lobulomycetales is based on species once classifi ed as members of the genus Chytriomyces but which molecular phylogenetic studies demonstrated were not monophyletic with C. hyalinus, the type of the genus (James et al., 2000(James et al., , 2006Letcher and Powell, 2002;Letcher et al., 2005). In molecular phylogenetic analyses, Chytriomyces angularis was found in a clade distant to the Chytridiales clade (James et al., 2006). ...
Chytridiomycota characteristically reproduce with posteriorly uniflagellate zoospores and are known as zoosporic fungi. Electron microscopic studies and molecular analyses of gene sequences have transformed our understanding of relationships within the Chytridiomycota. From syntheses of these data, systematics of zoosporic fungi is being rewritten, including the separation of Blastocladiomycota, Neocallimastigomycota and Monoblepharidomycota from the Chytridiomycota as new phyla. This chapter traces the recent history of zoosporic fungal taxonomy and summarizes our current classification of Chytridiomycota. Since the 1970s, the concept of distinct “zoospore types” based on a constellation of characters allowed zoospore ultrastructure to define orders in the Chytridiomycota. During the 1990s, phylogenetic analyses of gene sequences provided greater resolution needed to refine chytrid relationships, and by the 2000s classification decisions, even at the species level, applied molecular-based monophyly. Unexpectedly, molecular analyses of zoosporic fungi revealed the order Chytridiales as polyphyletic and composed of multiple distinct lineages. Revisionary systematic studies have now characterized several of these lineages as new orders for taxa previously classified in the Chytridiales. How lineages of zoosporic fungi evolved is controversial, but molecular-based.
... http://dx.doi.org/10.1101/451385 doi: bioRxiv preprint first posted online Oct. 24, 2018; Chytriomyces, and H. curvatum can be found in the literature, little appears to be known about the life history of these species (Forget et al. 2002;Letcher & Powell 2002;Powell et al. 2015;Ustinova et al. 2000). Many chytrids have similar, uninformative morphological features (James et al. 2000), and what appear to be successful isolations may not represent Batrachochytrium species. ...
Chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has caused amphibian population declines worldwide. Bd was first described in the 1990s and there are still geographic gaps in the genetic analysis of this globally distributed pathogen. Relatively few genetic studies have focused on regions where Bd exhibits low virulence, potentially creating a bias in our current knowledge of the pathogen's genetic diversity. Disease-associated declines have not been recorded in Texas (USA), yet Bd has been detected on amphibians in the state. These strains have not been isolated and characterized genetically; therefore, we isolated, cultured, and genotyped Bd from central Texas and compared isolates to a panel of previously genotyped strains distributed across the Western Hemisphere. We also isolated other chytrids not known to infect amphibians from east Texas. To identify larval amphibian hosts, we sequenced part of the COI gene. Among 37 Bd isolates from Texas, we detected 19 unique multi-locus genotypes, but found no genetic structure associated with host species, Texas localities, or across North America. Isolates from central Texas exhibit high diversity and genetically cluster with Bd-GPL isolates from the western U.S. that have caused amphibian population declines. This study genetically characterizes isolates of Bd from the south central U.S. and adds to the global knowledge of Bd genotypes.
Research into freshwater fungi has generated a wealth of information over the past decades with various published articles, i.e., reviews, books, and monographs. With the advancement of
methodologies used in freshwater fungal research, and numerous mycologists working on this ecological group, our knowledge progress and understanding of freshwater fungi, including novel
discoveries and new insights in the ecology of freshwater fungi, has advanced. With this enormous progress, it is timely that an updated account of freshwater fungi be compiled in one volume. Thus, this account is published to give a comprehensive overview of the different facets of freshwater fungal biology. It includes an updated classification scheme based on the latest taxonomic and phylogenetic analysis of freshwater fungal taxa, including their evolutionary history. The biology, diversity, and geographical distribution of higher and basal freshwater fungi are also discussed in the entries. A section on dispersal and adaptation of filamentous freshwater fungi is included in the present work. The ecological importance and role of fungi in the breakdown of wood in freshwater habitats, including their physiology, are discussed in detail. The biotechnological potential of freshwater fungi as producers of bioactive metabolites are reviewed, with methodologies in antimicrobial drug discovery. The present volume also provides an overview of different high throughput sequencing (HTS) platforms for freshwater fungal research highlighting their advantages and challenges, including recent studies of HTS in identification and quantification of fungal communities in freshwater habitats. The present volume also identifies the knowledge gaps and direction of future research in freshwater fungi.
A comprehensive account of fungal classification from freshwater habitats is outlined and discussed in the present review based on literature of biodiversity studies and recent morpho-phylogenetic analyses. A total of 3,870 freshwater fungal species are listed with additional details on the isolation source, habitat, geographical distribution, and molecular data. The Ascomycota (2,968 species, 1,018 genera) dominated the freshwater fungal taxa wherein Sordariomycetes (823 species, 298 genera) had the largest number, followed by Dothideomycetes (677 species, 229 genera), Eurotiomycetes (276 species, 49 genera), and Leotiomycetes (260 species, 83 genera). Other phyla included in the updated classification of freshwater fungi are: Chytridiomycota (333 species, 97 genera), Rozellomycota (221 species, 105 genera), Basidiomycota (218 species, 100 genera), Blastocladiomycota (47 species, 10 genera), Monoblepharomycota (29 species, 6 genera), Mucoromycota (19 species, 10 genera), Aphelidiomycota (15 species, 3 genera), Entomophthoromycota (6 species, 4 genera), Mortierellomycota (5 species, 3 genera), Olpidiomycota (4 species, 1 genus), Zoopagomycota (3 species, 2 genera), and Sanchytriomycota (2 species, 2 genera). The freshwater fungi belong to 1,361 genera, 386 families and 145 orders. The Pleosporales and Laboulbeniaceae are the largest freshwater fungal order and family comprised of 391 and 185 species, respectively. The most speciose genera are Chitonomyces (87, Laboulbeniomycetes), Verrucaria (50, Eurotiomycetes), Rhizophydium (52, Rhizophydiomycetes), Penicillium (47, Eurotiomycetes), and Candida (42, Saccharomycetes).
More than 300 species and 23 genera of Chytridiomycetes have been described since F.K. Sparrow's 1960 edition of Aquatic Phycomycetes, which contained monographic coverage of the class. Furthermore, recent authors have presented many new combinations and suggestions for synonymy. This bibliography is organized alphabetically by taxon and lists all new taxa and taxonomic changes that have been published since 1960. Entries for new species include information about substrates and habitats.
This paper brings together the species of Chytrid fungi recorded from large bodies of water in the British Isles. Four new species are described.