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Robert W. Lichtwardt - One of the best experts on this subject based on the ideXlab platform.
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Smittium spp trichomycetes
2016Co-Authors: Abdulaziz M Elbuni, Robert W. LichtwardtAbstract:SUMMARY Harvested asexual spores (trichospores) of Smittium culisetae, S. culicis, S. simulii, and S. mucronatum were used in this study. Only spores of the first three species were able to germinate in vitro, with S. culisetae demonstrating the highest percentage of germination. Germination may be accomplished either by a rapid extension of the inner spore wall in a process that (under the light microscope) resembles germ tube formation, or by rupturing the outer trichospore wall and the total emergence of the inner spore wall and protoplast. Spores germinated better in nonshaken tryptone-glucose-vitamin (TGv) medium than in shaken medium. Smzittium culisetae spores appear to have an inhibitor that reduces the percentage of germination under crowded conditions. Germination in S. culisetae occurred over a relatively wide range of temperatures and pH values, with maxima near 24-30 C and pH 6.0-7.8. Spores of S. culisetae survived storage in liquid nitrogen, but lost their viability at -15 C and when lyophilized. Features of trichospores that make the Harpellales especially adapted to surviving in the gut of immature aquatic insects have been outlined in a previous article (El-Buni and Lichtwardt, 1976) which dealt primarily with the physiology of spore formation. The emphasis in the present study is on factors affecting germination in cultured Smittium species. Germination, as we use the term with trichospores, involves the initial stages of growth and development of the inner spore with its distinct wall, within the outer trichospore wall, a process that differs morphologically from typical germination in other fungi. Ultrastructural interpretations of trichospore development and germination are the subject of a forthcoming paper by Moss and Lichtwardt and will not be dis
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Smittium spp trichomycetes
2016Co-Authors: Abdulaziz M Elbuni, Robert W. LichtwardtAbstract:SUMMARY Harvested asexual spores (trichospores) of Smittium culisetae, S. culicis, S. simulii, and S. mucronatum were used in this study. Only spores of the first three species were able to germinate in vitro, with S. culisetae demonstrating the highest percentage of germination. Germination may be accomplished either by a rapid extension of the inner spore wall in a process that (under the light microscope) resembles germ tube formation, or by rupturing the outer trichospore wall and the total emergence of the inner spore wall and protoplast. Spores germinated better in nonshaken tryptone-glucose-vitamin (TGv) medium than in shaken medium. Smzittium culisetae spores appear to have an inhibitor that reduces the percentage of germination under crowded conditions. Germination in S. culisetae occurred over a relatively wide range of temperatures and pH values, with maxima near 24-30 C and pH 6.0-7.8. Spores of S. culisetae survived storage in liquid nitrogen, but lost their viability at -15 C and when lyophilized. Features of trichospores that make the Harpellales especially adapted to surviving in the gut of immature aquatic insects have been outlined in a previous article (El-Buni and Lichtwardt, 1976) which dealt primarily with the physiology of spore formation. The emphasis in the present study is on factors affecting germination in cultured Smittium species. Germination, as we use the term with trichospores, involves the initial stages of growth and development of the inner spore with its distinct wall, within the outer trichospore wall, a process that differs morphologically from typical germination in other fungi. Ultrastructural interpretations of trichospore development and germination are the subject of a forthcoming paper by Moss and Lichtwardt and will not be dis
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costa rican gut fungi trichomycetes infeting lotic insect larvae
Revista De Biologia Tropical, 2015Co-Authors: Robert W. LichtwardtAbstract:Trichomycetes infecting freshwater Ephemeroptera and Diptera (Siinuliidae, Chironomidae) in various life zones oC Costa Rica were studied. Insect populations in 36 streams were sampled, a few repeatedly, at four different . perlods of time over seven years. Eleven new species of Harpellales are reported, plus six species known to occur also in n ontropical parts oi the world. Included are new species of Harpella and Pennella , a new monotypic genus ( Graminelloides) , and four new species of the previously monotypic genera Spartiella and Genistellospora . Seven new Smittium species, including three that are not named at this time, were cultured axenically. A new Amoebidium (Amoebidiales) was found in a stream polluted with organic matter. In the same polluted stream more species of dipteran larvae and a greater number of gut fungi were present than in stretclies of unpolluted water upstream. The overall diversity of Harpellales and their aquatic insect hosts in most Costa Rican streams appeared to be lower than what the author has found in many lotic habitats in more northem and southem regions of the world, and thus this order of fungi may be an exception to the 'latitudinal species diversity gradient' concept as it applies to many other tropical organisms. A key to all 23 Tric homycetes now known to be present in Costa Rica is provided
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using a five gene phylogeny to test morphology based hypotheses of Smittium and allies endosymbiotic gut fungi harpellales associated with arthropods
Molecular Phylogenetics and Evolution, 2014Co-Authors: Yan Wang, Robert W. Lichtwardt, Eric D Tretter, Eric M Johnson, Prasanna Kandel, Stephen J Novak, James F Smith, Merlin M. WhiteAbstract:Smittium, one of the first described genera of gut fungi, is part of a larger group of endosymbiotic microorganisms (Harpellales) that live predominantly in the digestive tracts of aquatic insects. As a diverse and species-rich taxon, Smittium has helped to advance our understanding of the gut fungi, in part due to the relative success of attempts to culture species of Smittium as compared to other members of Harpellales. Approximately 40% of the 81 known species of Smittium have been cultured. This is the first Smittium multigene dataset and phylogenetic analysis, using the 18S and 28S rRNA genes, as well as RPB1, RPB2, and MCM7 translated protein sequences. Several well-supported clades were recovered within Smittium. One includes the epitype S. mucronatum (the “True Smittium” clade), and another contains many species including S. simulii and S. orthocladii (the “ParaSmittium” clade). Ancestral states were reconstructed for holdfast shape, thallus branching type, as well as asexual (trichospore) and sexual (zygospore) spore morphology. Two of these characters, holdfast shape and trichospore morphology, supported the split of the two main clades revealed by the molecular phylogeny, suggesting these are natural clades and these traits may have evolutionary and perhaps ecological significance.
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overview of 75 years of Smittium research establishing a new genus for Smittium culisetae and prospects for future revisions of the Smittium clade
Mycologia, 2013Co-Authors: Yan Wang, Robert W. Lichtwardt, Eric D Tretter, Merlin M. WhiteAbstract:The Harpellales includes 38 genera of endosymbiotic microfungi associated with various Arthropoda. Smittium, the second genus to be described, is now also the most species rich of the order. Species of Smittium inhabit the digestive tracts of larval aquatic insects, especially lower Diptera, worldwide. During the 75 y since the type, Smittium arvernense, was described a number of advances in our understanding of the gut fungi have unfolded, in whole or in part, with Smittium as a model for the fungal trichomycetes. This in part relates to the high number of successful isolation attempts, with about 40% of known species having been cultured, a total number that far exceeds any other genus of gut fungus. Many isolates of Smittium have been used in laboratory studies for ultrastructural, physiological, host feeding, serological, as well as isozyme, and now ongoing molecular systematic studies. Molecular studies have shown that Smittium is polyphyletic but with consistent separation of Smittium culisetae, one of the most common and widespread species, from the remainder of Smittium. A brief overview of Smittium research is provided. Zygospore and trichos- pore morphology and molecular evidence (immuno- logical, isozyme, DNA sequences and phylogenetic analyses) are used to establish Zancudomyces and to accommodate Smittium culisetae. For the latter evidence, we include the first two-gene phylogenetic analysis, using combined 18S and 28S rRNA gene sequence data to show a cluster of Zancudomyces
John W Mccreadie - One of the best experts on this subject based on the ideXlab platform.
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seasonality and host usage of trichomycetes in larval black flies diptera simuliidae of southern alabama usa
Fungal Ecology, 2010Co-Authors: Mark P Nelder, Charles E. Beard, John W MccreadieAbstract:Abstract Larval black flies were collected monthly from streams in southern Alabama and assayed for the presence of gut fungi (trichomycetes). Eight trichomycete species were found, each showing seasonality and specific host usage. Trichomycete taxa collected were Genistellospora homothallica, Harpella melusinae, Harpella sp. 1, Pennella hovassi, Pennella simulii, Pennella sp. 1, Simuliomyces microsporus, and Smittium brasiliense, from the hosts Simulium decorum, Simulium jonsei, Simulium tribulatum, and Simulium ubiquitum. Seven trichomycete species were collected in the spring, summer (4), fall (2), and winter (4). S. ubiquitum hosted all 8 species of trichomycetes, S. jonsei (3), S. decorum (3) and S. tribulatum (2). Our results indicate that trichomycetes occupy a restricted subset of potential hosts and vary in prevalence according to season, independent of host prevalence.
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morphological differences of symbiotic fungi Smittium culisetae harpellales legeriomycetaceae in different dipteran hosts
Fungal Biology, 2009Co-Authors: Svjetlana Vojvodic, John W MccreadieAbstract:Abstract Harpellales (Legeriomycetaceae, Zygomycota) or ‘trichomycetes’ are fungi that inhabit the digestive tracts of arthropods such as insects, millipedes, and crustaceans. In the current study we examined changes in 5 morphological characters of Smittium culisetae (Harpellales: Legeriomycetaceae) between the two dipteran (mosquito, black fly) hosts reared under 3 different temperatures (17, 22, 30 °C). Both host and temperature had a pervasive effect on the linear dimension of trichospores, their generative cells and hyphae width. At 30 °C the mean size of all 5 morphological characters were consistently larger in fungus taken from the mosquito host than from the black fly host. At 17 °C and 22 °C, however, there were no consistent patterns. The effect of host was so pronounced that it could be accurately determined which host S. culisetae colonised based on differences in linear morphology. Such changes in fungal morphology between hosts have important ramifications for the morphologically based taxonomy of this group.
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do different species of Smittium harpellales legeriomycetaceae influence each other in the host gut
Fungal Biology, 2008Co-Authors: Svjetlana Vojvodic, John W MccreadieAbstract:Abstract Smittium ( Harpellales , Legeriomycetaceae ) belongs to a cosmopolitan group of filamentous fungi ( Trichomycetes , Zygomycota ) that live as obligate commensals in the digestive tract of various marine, freshwater, and terrestrial arthropods. The outcome of the paired introductions of three species of Smittium was investigated within the individual hosts of the mosquito Aedes aegypti ( Culicidae : Diptera ). In the first set of experiments, the host was inoculated with a single species of Smittium to determine whether hyphae location within the host was species specific. In the second experiment the host was exposed to two species of Smittium to determine whether hyphae showed positional displacement when two species of fungi co-inhabited the same host gut. Single species introductions of Smittium resulted in 80–85 % of hosts with hyphae present only in the rectum. In all three paired combinations of Smittium species examined, only 40–65 % of host larvae had hyphae restricted to the rectum. This is first study to experimentally demonstrate that the microdistribution of Harpellaceae hyphae can be influenced by the presence of a second species of Harpellaceae , suggesting a competition of the symbionts within the host.
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The effect of temperature and host species on the development of the trichomycete Smittium culisetae (Zygomycota)
Mycologia, 2007Co-Authors: Svjetlana Vojvodic, John W MccreadieAbstract:We examined the growth and development of the trichomycete Smittium culisetae (Harpellales: Legeriomycetaceae) in the larval hosts Simulium vittatum Zetterstedt (Diptera: Simuliidae) and Aedes aegypti (L.) (Diptera: Culicidae) at three temperatures, 17, 22 and 30 C. Trichospore maturation of Sm. culicetae external to the host as well as the ability of these trichospores to colonize new hosts also was investigated. Although the development of Sm. culisetae varied with both temperature and host there was a pattern of maximum trichospore production at 48-72 h postinoculation. In addition thalli under laboratory conditions are capable of spore production after extraction from a host and these trichospores can colonize new hosts. Furthermore this was noted to occur in both host species. These results suggest that synchrony between host and symbiont development is not as tightly coupled as previously assumed.
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influenceof fixation of the blackfly simulium vittatum on morphological characters of the trichomycete Smittium culisetae
2006Co-Authors: Mark P Nelder, John W MccreadieAbstract:The present study investigates the symbiotic trichomycete fungus Smittium culisetae (Harpellaceae: Legeriomycetaceae) in larvae of the blackfly Simulium vittatum Zetterstedt (Diptera: Simuliidae). Trichomycetes show some degree of host preference, but many species have been found inhabiting more than one host species. They therefore cannot be identified solely on the basis of the host species. Accordingly, morphological characters such as thallus and trichospore measurements are critical in species identification. Trichomycetes are typically identified from freshly dissected hosts, but the ability to identify fungi from preserved host material would provide a wealth of ecological and bio- geographical information. The intent of this study, therefore, was to examine the possibility of alteration of selected morphological characters in S.. culisetae from blackfly hosts fixed in 70% ethanol.
Marvin C Williams - One of the best experts on this subject based on the ideXlab platform.
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symbiotic harpellales trichomycetes in tasmanian aquatic insects
Mycologia, 2005Co-Authors: Leonard C. Ferrington, Robert W. Lichtwardt, Barbara Hayford, Marvin C WilliamsAbstract:Surveys for symbiotic fungi in the guts of aquatic insect larvae (Trichomycetes: Harpellales) in Tasmania, Australia, resulted in the discovery of four new species: two in Gripopterygidae (Plecoptera) nymphs, Plecopteromyces leptoperlarum and P. trinoto- perlarum, and two associated with Diptera larvae, Smittium magnosporum in Thaumaleidae and Stachy- lina dolichospora in Chironomidae. Previously de- scribed species of Harpellales from other localities are reported and new host records summarized. A key to all Tasmanian species of Harpellales is provid- ed.
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furculomyces a new homothallic genus of harpellales trichomycetes from australian midge larvae
Botany, 1992Co-Authors: Robert W. Lichtwardt, Marvin C WilliamsAbstract:A new genus, Furculomyces, is established for two Australian species of trichomycete gut fungi that live in the hindguts of aquatic Chironomidae (Diptera) larvae. The new genus is based primarily on the sexual apparatus consisting of a swollen pair of homothallic conjugants that resemble a wishbone, from which develops a slightly bent biconical zygospore. The type species, Furculomyces boomerangus comb, no v. (basionym: Smittium boomerangum) has been found in Victorian and Tasmanian midges, whereas the new species, Furculomyces westraliensis, is from a midge species in southern Western Australia. These species support other evidence that native Australian gut fungi have a provincial distribution. Key words: Australian, Chironomidae, fungi, Furculomyces, Harpellales, Trichomycetes.
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Smittium bullatum from a New Zealand midge larva and new records of other trichomycete gut fungi
Botany, 1992Co-Authors: Robert W. Lichtwardt, Marvin C WilliamsAbstract:An apparently uncommon gut fungus, Smittium bullatum (Trichomycetes, Harpellales), is described from Chironomidae (Orthocladiinae) larvae living in South Island, New Zealand, streams. Records of other Harpellales in South Island aquatic insects are reported, including the presence of zygospores of the New Zealand species Pennella asymmetrica from Simuliidae larvae. The richness of some harpellid gut fungi in New Zealand is compared with that in Australia and other parts of the world, and the biogeography of Smittium is discussed. Key words: biogeography, Chironomidae, Diptera, New Zealand, Smittium, Trichomycetes.
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Tasmanian Trichomycete gut fungi in aquatic insect larvae.
Mycologia, 1992Co-Authors: Robert W. Lichtwardt, Marvin C WilliamsAbstract:A fourth species of the Australasian genus AustroSmittium, A. biforme (Trichomycetes, Harpellales), has been found. This gut fungus from Chironomidae larvae collected in a Tasmanian stream has the unusual feature of producing two distinctly different sizes of trichospores. Two new Tasmanian species of the more common genus Smittium, S. compactum and S. fastigatum, are described from lotic chironomid larvae. A new species of Harpellales from Tasmanian mayfly nymphs is also described and illustrated, but not named; it may represent a new genus that has similarities to Bojamyces repens recently described from the USA. New records of other Tasmanian trichomycetes from aquatic insects are provided.
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western australian species of Smittium and other trichomycetes in aquatic insect larvae
Mycologia, 1992Co-Authors: Robert W. Lichtwardt, Marvin C WilliamsAbstract:Three species of Smittium (Trichomycetes, Harpellales) that may be endemic to Western Australia are described from the hindguts of midge larvae (Diptera, Chironomidae): S. fruticosum, S. angustum and S. microsporum. Axenic cultures were obtained of the latter two fungal species. The occurrence in Western Australia of six geographically widespread species of other Harpellales from dipteran guts is reported together with records of Paramoebidium spp. (Amoebidiales) in Chironomidae and Ephemeroptera.
Merlin M. White - One of the best experts on this subject based on the ideXlab platform.
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diversification of the gut fungi Smittium and allies harpellales co occurred with the origin of complete metamorphosis of their symbiotic insect hosts lower diptera
Molecular Phylogenetics and Evolution, 2019Co-Authors: Yan Wang, Merlin M. White, Jeanmarc MoncalvoAbstract:Abstract Smittium (Harpellales, Kickxellomycotina) includes fungal symbionts associated with the digestive tracts of immature aquatic stages of various Diptera, including Chironomidae, Culicidae, Dixidae, Simuliidae, Thaumaleidae, and Tipulidae. With 84 species and the largest collection of cultured strains, Smittium has served as a model to understand the biology of these enigmatic trichomycetes gut fungi, from aspects of biodiversity, evolution, genomics, immunology, and physiology. However, evolutionary histories between Smittium species and their hosts are still not firmly established. Robust phylogenies of both Smittium sensu lato (s.l.) and their lower Diptera hosts have been reconstructed separately, facilitating comparative evolutionary studies between the two. The divergence time of the Smittium s.l. clade was estimated for the first time and compared with the evolutionary history of the insect hosts. The insect gut fungi diversified around 272 Ma (204–342 Ma), which co-occurred with the origin of complete metamorphosis of the insect hosts, presumably between 280 Ma and 355 Ma (~270 Ma for Diptera). A co-phylogenetic pattern was recovered for the insects and their symbiotic gut fungi using the statistical method ParaFit. Ancestral state reconstructions of the symbiotic relationship suggest that the ancestor of the Chironomidae may have contributed to the initiation of these insect-fungus symbiotic interactions. Further sampling and sequencing of Smittium and allies as well as their hosts are needed to uncover more patterns and interactions that may occur in this type of symbiosis.
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using a five gene phylogeny to test morphology based hypotheses of Smittium and allies endosymbiotic gut fungi harpellales associated with arthropods
Molecular Phylogenetics and Evolution, 2014Co-Authors: Yan Wang, Robert W. Lichtwardt, Eric D Tretter, Eric M Johnson, Prasanna Kandel, Stephen J Novak, James F Smith, Merlin M. WhiteAbstract:Smittium, one of the first described genera of gut fungi, is part of a larger group of endosymbiotic microorganisms (Harpellales) that live predominantly in the digestive tracts of aquatic insects. As a diverse and species-rich taxon, Smittium has helped to advance our understanding of the gut fungi, in part due to the relative success of attempts to culture species of Smittium as compared to other members of Harpellales. Approximately 40% of the 81 known species of Smittium have been cultured. This is the first Smittium multigene dataset and phylogenetic analysis, using the 18S and 28S rRNA genes, as well as RPB1, RPB2, and MCM7 translated protein sequences. Several well-supported clades were recovered within Smittium. One includes the epitype S. mucronatum (the “True Smittium” clade), and another contains many species including S. simulii and S. orthocladii (the “ParaSmittium” clade). Ancestral states were reconstructed for holdfast shape, thallus branching type, as well as asexual (trichospore) and sexual (zygospore) spore morphology. Two of these characters, holdfast shape and trichospore morphology, supported the split of the two main clades revealed by the molecular phylogeny, suggesting these are natural clades and these traits may have evolutionary and perhaps ecological significance.
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overview of 75 years of Smittium research establishing a new genus for Smittium culisetae and prospects for future revisions of the Smittium clade
Mycologia, 2013Co-Authors: Yan Wang, Robert W. Lichtwardt, Eric D Tretter, Merlin M. WhiteAbstract:The Harpellales includes 38 genera of endosymbiotic microfungi associated with various Arthropoda. Smittium, the second genus to be described, is now also the most species rich of the order. Species of Smittium inhabit the digestive tracts of larval aquatic insects, especially lower Diptera, worldwide. During the 75 y since the type, Smittium arvernense, was described a number of advances in our understanding of the gut fungi have unfolded, in whole or in part, with Smittium as a model for the fungal trichomycetes. This in part relates to the high number of successful isolation attempts, with about 40% of known species having been cultured, a total number that far exceeds any other genus of gut fungus. Many isolates of Smittium have been used in laboratory studies for ultrastructural, physiological, host feeding, serological, as well as isozyme, and now ongoing molecular systematic studies. Molecular studies have shown that Smittium is polyphyletic but with consistent separation of Smittium culisetae, one of the most common and widespread species, from the remainder of Smittium. A brief overview of Smittium research is provided. Zygospore and trichos- pore morphology and molecular evidence (immuno- logical, isozyme, DNA sequences and phylogenetic analyses) are used to establish Zancudomyces and to accommodate Smittium culisetae. For the latter evidence, we include the first two-gene phylogenetic analysis, using combined 18S and 28S rRNA gene sequence data to show a cluster of Zancudomyces
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new species of Smittium and stachylina and other trichomycetes in larval diptera from streams in nova scotia canada 1this paper is dedicated to jo ann frost one of the first students of these fungi in nova scotia and to the numerous other undergradua
Botany, 2012Co-Authors: Merlin M. White, D.b. StrongmanAbstract:The guts of non-predaceous invertebrates in aquatic and moist terrestrial habitats are often colonized by an ecological group of microorganisms called trichomycetes. Taxonomically, these endobionts are currently a diverse, polyphyletic assemblage including both zygomycetous fungi as well as protistan species. Trichomycetes are worldwide in distribution and are from varied habitats, but the species inventory of gut fungi from hosts in Canada is far from complete. We summarize the findings from our earliest surveys (from 1997 to 2005) and collections of candidate dipteran hosts in Nova Scotia. Nine new species of gut fungi are added to the inventory list, including the following seven Smittium spp.: Smittium aggregatum, Smittium gronthidium, Smittium papillum, Smittium pavocaudatum, Smittium radiculans, Smittium sparsum, and Smittium verticillatum, and the following two Stachylina spp.: Stachylina brevicellaris and Stachylina subgrandis. Four of the other 13 Harpellales, Pennella digitata, Smittium megazygosporum, Stachylina penetralis, and Zancudomyces culisetae are reported for the first time in Atlantic Canada. Also recorded is Paramoebidiumcurvum, with many more specimens of this genus from various locations and hosts included as Paramoebidium spp. only. We suggest that future collections of Diptera, to further document and discover trichomycetes, are warranted across the varied host habitats that abound not only in eastern Canada but the rest of the country as well.
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new species and first records of trichomycetes from immature aquatic insects in idaho
Mycologia, 2012Co-Authors: Molly E Bench, Merlin M. WhiteAbstract:Trichomycetes, or gut fungi, are currently recognized as an ecological group of fungi and protists that inhabit the guts of immature insects or other stages and types of arthropods. The geographic distribution of these endosymbionts is worldwide. However trichomycete data from the Pacific Northwest are limited and this is the first account of gut fungi in Idaho. We report on the trichomycetes from a single site, Cottonwood Creek at Military Reserve Park, Boise, Idaho, where periodic surveys for more than a year resulted in the discovery of four newly named, three probably new but unnamed and 15 previously known species. Among the Harpellales three new species, Capniomyces sasquatchoides, Harpella torus and Lancisporomyces lampetriformis, are described, with two possibly new species of Smittium detailed but unnamed at this time pending further collections. A Genistelloides cf. hibernus also is included as a possible new species. One new species of Amoebidiales, Paramoebidium hamatum, is described as well. ...
Charles E. Beard - One of the best experts on this subject based on the ideXlab platform.
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seasonality and host usage of trichomycetes in larval black flies diptera simuliidae of southern alabama usa
Fungal Ecology, 2010Co-Authors: Mark P Nelder, Charles E. Beard, John W MccreadieAbstract:Abstract Larval black flies were collected monthly from streams in southern Alabama and assayed for the presence of gut fungi (trichomycetes). Eight trichomycete species were found, each showing seasonality and specific host usage. Trichomycete taxa collected were Genistellospora homothallica, Harpella melusinae, Harpella sp. 1, Pennella hovassi, Pennella simulii, Pennella sp. 1, Simuliomyces microsporus, and Smittium brasiliense, from the hosts Simulium decorum, Simulium jonsei, Simulium tribulatum, and Simulium ubiquitum. Seven trichomycete species were collected in the spring, summer (4), fall (2), and winter (4). S. ubiquitum hosted all 8 species of trichomycetes, S. jonsei (3), S. decorum (3) and S. tribulatum (2). Our results indicate that trichomycetes occupy a restricted subset of potential hosts and vary in prevalence according to season, independent of host prevalence.
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Laboratory investigations of trichomycete prevalence, abundance and fecundity in a Smittium-simuliid model
Mycologia, 2005Co-Authors: Mark P Nelder, John W Mccreadie, Charles E. BeardAbstract:Smittium, the most speciose genus of the "gut fungi" (Zygomycota: Trichomycetes), is found attached to the hindgut cuticle of larval aquatic Dip- tera. Smittium spp. colonize several host families (e.g., Smittium culisetae in Chironomidae, Culicidae and Simuliidae), but some species appear to be spe- cific to a single host family (e.g., Smittium morbosum Sweeney in Culicidae). The specificity of Smittium spp. within a host family has been difficult to resolve. This research presents evidence that certain Smittium spp. differentially colonize particular species of black fly (Diptera: Simuliidae) hosts as measured by differ- ences in prevalence, abundance and fecundity. Rea- sons for this differential occurrence and fecundity in hosts are unclear but might include fungal responses to variations in host morphology, physiology, distri- bution or behavior. Variable fitness of Smittium spp., within a suite of available hosts, could be a factor in
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laboratory investigations of trichomycete prevalence abundance and fecundity in a Smittium simuliid model
Mycologia, 2005Co-Authors: Mark P Nelder, John W Mccreadie, Charles E. BeardAbstract:Smittium, the most speciose genus of the "gut fungi" (Zygomycota: Trichomycetes), is found attached to the hindgut cuticle of larval aquatic Diptera. Smittium spp. colonize several host families (e.g., Smittium culisetae in Chironomidae, Culicidae and Simuliidae), but some species appear to be specific to a single host family (e.g., Smittium morbosum Sweeney in Culicidae). The specificity of Smittium spp. within a host family has been difficult to resolve. This research presents evidence that certain Smittium spp. differentially colonize particular species of black fly (Diptera: Simuliidae) hosts as measured by differences in prevalence, abundance and fecundity. Reasons for this differential occurrence and fecundity in hosts are unclear but might include fungal responses to variations in host morphology, physiology, distribution or behavior. Variable fitness of Smittium spp., within a suite of available hosts, could be a factor in the diversity of this fungal group.
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Context‐dependent symbiosis between black flies (Diptera: Simuliidae) and trichomycete fungi (Harpellales: Legeriomycetaceae)
Oikos, 2005Co-Authors: John W Mccreadie, Charles E. Beard, Peter H. AdlerAbstract:The context-dependent nature of a symbiotic relationship between a trichomycete fungus (Smittium culisetae) and a larval black fly (Simulium vittatum) is demonstrated in the present study. No significant difference was found between the size of larvae colonized by trichomycetes and those free of trichomycetes, regardless of the trichospore dosage or initial age of the larvae. This trend suggests that the trichomycete has no detectable effect on host fitness, indicating a commensalistic relationship. However, in half of the experiments, stressed (i.e. starved) larvae exposed to trichospores at a dosage of 20 000 spores ml -1 had significantly higher survival than did trichomycete-free larvae, indicating a mutualistic relationship. Trichomycetes in adult female black flies can replace the ovaries. The symbiotic association between trichomycetes and simuliids, therefore, is dynamic: commensalistic when larvae are well fed, mutualistic when larvae are starved, and parasitic in adults. The trichomyceteblack fly relationship represents a rare case of symbiosis shifting among three states.
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Trichomycete symbiotes of Crozetia seguyi, a primitive black fly.
Journal of Invertebrate Pathology, 2004Co-Authors: Will K. Reeves, Charles E. Beard, Douglas A CraigAbstract:Abstract Crozetia is a genus of black flies endemic to the Crozet Islands in the Indian Ocean. No internal symbiotes were previously known from Crozetia species. We report two species of trichomycete symbiotes Stachylina litoralis and Smittium culicisoides from Crozetia seguyi. Larvae of C. seguyi were examined from three sites. The infection rates for St. litoralis was 10.0–33.3% (n = 47) of the larvae and Sm. culicisoides was 46.1–85.7% (n = 47). No other symbiotes were discovered.
