Examining the Effectiveness of Social Media for the Dissemination of Research Evidence for Health and Social Care Practitioners: Systematic Review and Meta-Analysis.

BACKGROUND: Social media use has potential to facilitate the rapid dissemination of research evidence to busy health and social care practitioners. OBJECTIVE: This study aims to quantitatively synthesize evidence of the between- and within-group effectiveness of social media for dissemination of research evidence to health and social care practitioners. It also compared effectiveness between different social media platforms, formats, and strategies. METHODS: We searched electronic databases for articles in English that were published between January 1, 2010, and January 10, 2023, and that evaluated social media interventions for disseminating research evidence to qualified, postregistration health and social care practitioners in measures of reach, engagement, direct dissemination, or impact. Screening, data extraction, and risk of bias assessments were carried out by at least 2 independent reviewers. Meta-analyses of standardized pooled effects were carried out for between- and within-group effectiveness of social media and comparisons between platforms, formats, and strategies. Certainty of evidence for outcomes was assessed using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) framework. RESULTS: In total, 50 mixed-quality articles that were heterogeneous in design and outcome were included (n=9, 18% were randomized controlled trials [RCTs]). Reach (measured in number of practitioners, impressions, or post views) was reported in 26 studies. Engagement (measured in likes or post interactions) was evaluated in 21 studies. Direct dissemination (measured in link clicks, article views, downloads, or altmetric attention score) was analyzed in 23 studies (8 RCTs). Impact (measured in citations or measures of thinking and practice) was reported in 13 studies. Included studies almost universally indicated effects in favor of social media interventions, although effect sizes varied. Cumulative evidence indicated moderate certainty of large and moderate between-group effects of social media interventions on direct dissemination (standardized mean difference [SMD] 0.88; P=.02) and impact (SMD 0.76; P<.001). After social media interventions, cumulative evidence showed moderate certainty of large within-group effects on reach (SMD 1.99; P<.001), engagement (SMD 3.74; P<.001), and direct dissemination (SMD 0.82; P=.004) and low certainty of a small within-group effect on impacting thinking or practice (SMD 0.45; P=.02). There was also evidence for the effectiveness of using multiple social media platforms (including Twitter, subsequently rebranded X; and Facebook), images (particularly infographics), and intensive social media strategies with frequent, daily posts and involving influential others. No included studies tested the dissemination of research evidence to social care practitioners. CONCLUSIONS: Social media was effective for disseminating research evidence to health care practitioners. More intense social media campaigns using specific platforms, formats, and strategies may be more effective than less intense interventions. Implications include recommendations for effective dissemination of research evidence to health care practitioners and further RCTs in this field, particularly investigating the dissemination of social care research. TRIAL REGISTRATION: PROSPERO International Prospective Register of Systematic Reviews CRD42022378793; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=378793. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.2196/45684.

Learning from Nursing Home Infection Prevention and Control Citations During the COVID-19 Pandemic.

The devastating effects of coronavirus disease 2019 (COVID-19) highlight the critical need for effective infection prevention and control (IPC) practices in nursing homes. Nursing management and infection preventionists should be cognizant of the most common reasons underlying federal IPC citations during the pandemic. Analysis of IPC citation data from the first 7 months of the public health emergency identified that adherence to personal protective equipment (PPE) and mask use, appropriate transmission-based precautions, and hand hygiene were the most common reasons for COVID-19-related F880 citations, including those that placed a person at immediate risk for serious injury or death. More specific staff practices and other factors leading to a citation are also highlighted. Although nursing homes may have limited control over factors such as PPE supply and staffing resources, nursing management and infection preventionists can use these results to help ensure that operational mechanisms, staff training, and adherence monitoring efforts effectively address the areas most associated with COVID-19 IPC noncompliance. [Journal of Gerontological Nursing, 49(2), 36-42.].

Cytochemical Localization of Polyphenol Oxidase Activity in K2-Bodies of Saprolegnia ferax Secondary Zoospores.

Zoospores of the oomycete Saprolegnia ferax release adhesive material from K-bodies at the onset of attachment to substrates. To understand more fully how K-bodies function in adhesion, enzyme activity was investigated cytochemically in secondary zoospores. Presence of catalase, a marker enzyme for microbodies, was explored in the diaminobenzidine (DAB) reaction. Although pH 9.2 DAB-staining characteristic of catalase activity was detected in the granular matrix regions of K-bodies, reaction controls indicated that the reaction was due to oxidative enzyme activity other than catalase. Because polyphenol oxidase (PPO) is another metal-containing enzyme capable of oxidizing DAB, activity of this enzyme was tested with a more specific substrate, dihydroxyphenylalanine (DOPA). In the DOPA procedure, reaction product was exclusively localized within K-bodies, indicating the presence of PPO. Results with three methods of reaction controls (elimination of substrate, addition of a PPO enzyme inhibitor, and heat-inactivation of enzymes) all supported the presence of PPO in K-bodies. This study highlights potential roles for K-body PPO in stabilization of adhesion bodies by: cross-linking matrix phenolic proteins or glycoproteins as K-bodies discharge adhesives onto substrates, or polymerizing phenolics protective against microbial attacks of the adhesion pad.

Revisions to the Classification, Nomenclature, and Diversity of Eukaryotes.

This revision of the classification of eukaryotes follows that of Adl et al., 2012 [J. Euk. Microbiol. 59(5)] and retains an emphasis on protists. Changes since have improved the resolution of many nodes in phylogenetic analyses. For some clades even families are being clearly resolved. As we had predicted, environmental sampling in the intervening years has massively increased the genetic information at hand. Consequently, we have discovered novel clades, exciting new genera and uncovered a massive species level diversity beyond the morphological species descriptions. Several clades known from environmental samples only have now found their home. Sampling soils, deeper marine waters and the deep sea will continue to fill us with surprises. The main changes in this revision are the confirmation that eukaryotes form at least two domains, the loss of monophyly in the Excavata, robust support for the Haptista and Cryptista. We provide suggested primer sets for DNA sequences from environmental samples that are effective for each clade. We have provided a guide to trophic functional guilds in an appendix, to facilitate the interpretation of environmental samples, and a standardized taxonomic guide for East Asian users.

Morphology, Ultrastructure, and Molecular Phylogeny of Rozella multimorpha, a New Species in Cryptomycota.

Increasing numbers of sequences of basal fungi from environmental DNA studies are being deposited in public databases. Many of these sequences remain unclassified below the phylum level because sequence information from identified species is sparse. Lack of basic biological knowledge due to a dearth of identified species is extreme in Cryptomycota, a new phylum widespread in the environment and phylogenetically basal within the fungal lineage. Consequently, we are attempting to fill gaps in the knowledge of Rozella, the best-known genus in this lineage. Rozella is a genus of unwalled, holocarpic, endobiotic parasites of hosts including Chytridiomycota, Blastocladiomycota, Oomycota, Basidiomycota, and a green alga, with most species descriptions based on morphology and host specificity. We found a Rozella parasitizing a Pythium host that was a saprobe on spruce pollen bait placed with an aquatic sample. We characterized the parasite with light microscopy, TEM of its zoospores and sporangia, and its 18S/28S rDNA. Comparison with other Rozella species indicates that the new isolate differs morphologically, ultrastructurally, and genetically from Rozella species for which we have data. Features of the zoospore also differ from those of previously studied species. Herein we describe the Rozella as a new species, R. multimorpha.

Molecular Phylogeny and Ultrastructure of Aphelidium desmodesmi, a New Species in Aphelida (Opisthosporidia).

Aphelids are a diverse group of intracellular parasitoids of algae and diatoms, and are sister to true fungi. Included in four genera, the 14 described species utilize phagocytosis as their mode of nutrition, and the life cycles of these taxa are remarkably similar. However, their putative specificity of host, morphological and ultrastructural features, and genetic divergence have been considered in taxon delineation. Here, we examine the host specificity, morphology, ultrastructure, and molecular 18S gene sequence of a new species in Aphelida, Aphelidium desmodesmi sp. nov. This taxon is in a well-supported clade with two other species of Aphelidium, and this lineage is sister to Amoeboaphelidium and Paraphelidium. Of interest, the mitochondrial structure of Aph. desmodesmi is more like that of Paraphelidium than that of Aphelidium aff. melosirae, the only other species of Aphelidium to have been examined ultrastructurally. This research examines and expands our understanding of host range, morphological diversity, and genetic divergence of the aphelids.

Characterization of a new chytrid species parasitic on the dinoflagellate, Peridinium gatunense.

Only a few chytrid fungi have been reported as parasites of dinoflagellates. Among these reports, chytrids are periodically observed growing on the dinoflagellate, Peridinium gatunense, in Lake Kinneret (Sea of Galilee), Israel. Because of the distinctive roles of parasitic chytrid fungi in decreasing phytoplankton populations and in transforming inedible algae into chytrid biomass which zooplankton grazers can eat, characterizing dinoflagellate parasites contributes to our understanding of the sustainability of this important water resource. An undescribed chytrid parasite of P. gatunense from Lake Kinneret has recently been brought into pure culture (KLL_TL-060613), facilitating exploration of its infection process. To evaluate the ability of this chytrid to affect host populations, we determined the effect of: (1) temperature and light (or dark) on prevalence of infection and (2) host growth phase and parasite:host ratio on percentage of infection. The greatest amplification in host infection occurred in cultures grown in the dark at 25 C. The percentage of host cells infected increased as the availability of host cells compared to parasite cells increased. These results demonstrate that environmental factors influence the chytrid's potential to affect Peridinium gatunense populations. Because this chytrid had not been described taxonomically, we characterized its thallus morphology, development, zoospore ultrastructure and phylogenetic relationships. Zoospore ultrastructure was compatible with the Group II type zoospore characteristic of the family Chytridiaceae in the Chytridiales. Consistent with this observation, phylogenetic analyses of nuc 28S rDNA D1-D3 domains (28S) placed the chytrid in a clade among described taxa in the Chytridiaceae. Because thallus morphology was distinct from these other taxa, as well as other described parasites of dinoflagellates, this chytrid is described as a new genus and species, Dinochytrium kinnereticum.

Borealophlyctis nickersoniae, a new species in Rhizophlyctidales.

Zoospore ultrastructural characters combined with molecular phylogenetic hypotheses have been used to revise the taxonomy of zoosporic true fungi. An example is the reclassification of Rhizophlyctis rosea-like fungal strains into four new families and three new genera within the order Rhizophlyctidales. One genus was Borealophlyctis, which included a Canadian isolate, DAOMC 229843. A recent survey of chytrid diversity in Alabama (USA) yielded additional strains (WJD 170, WJD 171) in the Borealophlyctis lineage. With light and transmission-electron microscopy we examined strains DAOMC 229843, WJD 170 and WJD 171. We also analyzed partial nuc 28S rDNA D1-D3 domains (28S) and nuc rDNA region encompassing the internal transcribed spacers 1 and 2 and 5.8S (ITS) sequences to determine the phylogenetic placement of the strains within Rhizophlyctidales. Based on molecular divergence and morphological differences from the type Borealophlyctis paxensis, we recognize DAOMC 229843, WJD 170 and WJD 171 as representatives of the new species Borealophlyctis nickersoniae.

A new family and four new genera in Rhizophydiales (Chytridiomycota).

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+Phlyctochytrium mangrovei, (ii) three strains of Rhizophydium aestuarii and (iii) five previously unidentified strains. Light microscopic observations revealed four distinct thallus morphologies, and zoospore ultrastructural analyses revealed four distinct constellations of ultrastructural features. On the bases of morphological, ultrastructural and molecular evidence we place these strains in the new family Halomycetaceae and four new genera (Halomyces, Paludomyces, Ulkenomyces, Paranamyces) in Rhizophydiales.

Fayochytriomyces, a new genus within Chytridiales.

Chytriomyces is a complex genus in Chytridiales. The morphological concept of the genus expanded as new taxa were added, and studies of zoospore ultrastructure and molecular phylogenies have revealed the genus to be polyphyletic. One problematic taxon is C. spinosus Fay, a distinctive species characterized by whorls of spines on the zoosporangium and a large accumulation of vesicle material beneath the operculum. With light-, scanning-electron and transmission-electron microscopy, we examined a culture (WJD186) isolated from a muck sample collected from a temporary forest pond. We also analyzed the D1-D2 variable domains of the nuc 28S rDNA (28S) sequences to confirm the phylogenetic placement of the species relative to the type of Chytriomyces, C. hyalinus Karling. The morphology of culture WJD186 is consistent with features Fay described for C. spinosus, and the zoospore ultrastructure is consistent with the Group I-type zoospore characters of Chytriomycetaceae (Chytridiales). In our molecular phylogeny C. spinosus does not group with the type of Chytriomyces. Consequently, we erect a new genus in Chytriomycetaceae and present the new combination Fayochytriomyces spinosus.

A new genus and family for the misclassified chytrid, Rhizophlyctis harderi.

A chytrid first discovered in Mediterranean sands and called Rhizophlyctis harderi was classified in the genus Rhizophlyctis based on its interbiotic vegetative thalli with multiple rhizoidal axes and resting thalli with tufts of rhizoid-like appendages. Developmental, electron microscopic and molecular analyses, however, have brought into question the proper placement of this chytrid. Because its original description was in German and not Latin, the name R. harderi is not validly published. We found that this chytrid produces three thallus forms that could place it in three different morpho-genera: Rhizophydium, Phlyctochytrium or Rhizophlyctis. The ultrastructural architecture of its zoospore is different from that of zoospores of Rhizophlyctis rosea, the type species for Rhizophlyctis, and shares zoospore ultrastructural characteristics with the Rhizophydiales. Zoospores of this chytrid exhibit a distinctive kinetosome-associated structure (KAS), a curved shield bridged to two of the kinetosomal triplets and a layered cap anterior to the kinetosome. Phylogenetic analyses of nuc rDNA also support the placement of this chytrid in the Rhizophydiales and not in the Rhizophlyctidales. Given its molecularly based phylogenetic placement and its distinctive zoospore architecture, we describe this chytrid in a new genus, Uebelmesseromyces, in the Rhizophydiales and erect Uebelmesseromycetaceae as a new family to accommodate it.

A new isolate of Amoeboaphelidium protococcarum, and Amoeboaphelidium occidentale, a new species in phylum Aphelida (Opisthosporidia).

Microalgae used in the production of biofuels represents an alternative to fossil fuels. One problem in the production of algae for biofuels is attacks by algal parasitoids that can cause population crashes when algae are cultivated in outdoor ponds (Greenwell et al. 2010). Integrated solutions are being sought to mitigate this problem, and an initial step is pest identification. We isolated an algal parasitoid from an open pond of Scenedesmus dimorphus used for biofuel production in New Mexico and examined its morphology, ultrastructure and molecular phylogeny. A phylogenetic analysis placed this organism in Aphelida as conspecific with Amoeboaphelidium protococcarum sensu Karpov et al. 2013. As a result we re-evaluated the taxonomy of Amoeboaphelidium protococcarum sensu Letcher et al. 2013 and here designate it as a new species, Amoeboaphelidium occidentale.

Hypothesized evolutionary trends in zoospore ultrastructural characters in Chytridiales (Chytridiomycota).

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 ancestral and derived states. The sixth character, structure of the paracrystalline inclusion, did not resolve ancestral and derived states. In each of the lineages within Chytridiales, the evolutionary trend appears to have been from a more complex zoospore to a less complex zoospore with reduced features. As we isolate and analyze additional taxa, we discover new ultrastructural character states that assist in taxon delineation and phylogenetic interpretation.

Dendrochytridium crassum gen. et sp. nov., a taxon in Chytridiales with unique zoospore ultrastructure.

A water culture of detritus collected from an Australian tree canopy yielded multiple isolates (designated JEL 352, JEL 353, JEL 354) of an unidentified chytrid that grew on pollen bait and encysted spores of a Dictyuchus sp. oomycete. Morphological information from JEL 352 and genetic information from JEL 354 of this unidentified chytrid have been in several publications but the organism has not been named. Because isolates JEL 352 and JEL 354 are no longer viable, we sequenced partial SSU and LSU rDNA of isolate JEL 353, documented its thallus morphology with light microscopy and determined its zoospore ultrastructure via transmission electron microscopy. DNA evidence placed JEL 353 in Chytridiaceae, and its genetic composition was identical to that of JEL 354. Thallus morphology of JEL 353 was similar to that of JEL 352. Its zoospore ultrastructure is less complex compared to other members of Chytridiaceae. In pure culture, the rhizoidal system differed from other members of the family in being unevenly broad and not tapering to fine tips. Based on genetic, morphological and ultrastructural evidence, we place this chytrid in a new genus in Chytridiaceae and describe it as the new species Dendrochytridium crassum.

Irineochytrium, a new genus in Chytridiales having zoospores and aplanospores.

Many described chytrids exhibit distinct morphological features that permit positive identification by light microscopy. Chytriomyces annulatus is one such species. It has a flap-like operculum and its sporangial wall is ornamented with multiple collar-like annulations proximal to the rhizoidal axis, features that, in combination, do not occur in any other described chytrid. Recent molecular phylogenies placed C. annulatus in the Chytridiaceae (Chytridiales) lineage, which is characterized by a Group II zoospore. Here we use light microscopy and transmission electron microscopy to examine thallus morphology of an isolate (JEL 729) of C. annulatus to confirm its identity and transmission electron microscopy to examine zoospore ultrastructure to confirm its phylogenetic placement. Light microscopic examinations confirmed its identity, and transmission electron microscopy analysis revealed both motile spores (zoospores) and nonmotile spores (aplanospores). Zoospores had a unique suite of ultrastructural features characteristic of the Group II zoospore; aplanospores had similar ultrastructure minus a flagellum. Chytriomyces annulatus does not group with the Chytriomycetaceae (Chytridiales) lineage containing the type of Chytriomyces, C. hyalinus, nor does it have a zoospore typical of that lineage. These arguments support the recognition of a distinct genus in Chytridiaceae, including one species, Irineochytrium annulatum.

Pseudorhizidium is a new genus with distinct zoospore ultrastructure in the order Chytridiales.

A chytrid isolate (JEL 221) we identified as the rarely reported species, Rhizidium endosporangiatum Karling, was cultured axenically for the first time. The purposes of this study are to characterize the developmental morphology of isolate JEL 221 and to elucidate its zoospore ultrastructural features. Thallus development and morphology of isolate JEL 221 are characteristic of R. endosporangiatum as it was originally described. However, thallus morphology of R. endosporangiatum is not entirely typical of the genus Rhizidium, especially that of the type R. mycophilum. The presence of an endosporangium, a layer of material encapsulating the edges of the protoplast protruding through multiple discharge pores, makes this a distinctive species. Consistent with its published molecular-based phylogenetic placement, we found that isolate JEL 221 shared ultrastructural features with the two major zoospore types described for the Chytridiales but had distinct zoospore architecture. A new genus, Pseudorhizidium, is erected for this chytrid based on its thallus morphology, molecular phylogenetic placement and unique zoospore ultrastructure. This new genus does not fit into either of the described families (Chytridiaceae or Chytriomycetaceae) in the Chytridiales because of its unique zoospore ultrastructure, especially the two-layered nature of the electron-opaque plug in the base of the flagellum.

Three new genera in Chytridiales from aquatic habitats in Argentina.

Sampling for chytrids in a variety of habitats has resulted in pure cultures that when analyzed have yielded hypotheses of relationships based on molecular and zoospore ultrastructural markers. To extend our understanding of diversity of Chytridiales in eastern Argentina and USA, we isolated and examined the morphology, ultrastructure and 28S and ITS1-5.8S-ITS2 rDNA sequences of numerous chytrids from aquatic habitats from these two regions. Three family-level lineages (Chytridiaceae, Chytriomycetaceae, family incertae sedis) are represented in our molecular phylogeny, and three new genera (Avachytrium, Odontochytrium in Chytriomycetaceae, Delfinachytrium in family incertae sedis) are described. These findings of new genera and species emphasize the potential for discovery of additional diversity.

The Use of Social Media for Dissemination of Research Evidence to Health and Social Care Practitioners: Protocol for a Systematic Review.

BACKGROUND: Effective dissemination of research to health and social care practitioners enhances clinical practice and evidence-based care. Social media use has potential to facilitate dissemination to busy practitioners. OBJECTIVE: This is a protocol for a systematic review that will quantitatively synthesize evidence of the effectiveness of social media, compared with no social media, for dissemination of research evidence to health and social care practitioners. Social media platforms, formats, and sharing mechanisms used for effective dissemination of research evidence will also be identified and compared. METHODS: Electronic database searches (MEDLINE, PsycINFO, CINAHL, ERIC, LISTA, and OpenGrey) will be conducted from January 1, 2010, to January 10, 2023, for studies published in English. Randomized, nonrandomized, pre-post study designs or case studies evaluating the effect of social media on dissemination of research evidence to postregistration health and social care practitioners will be included. Studies that do not involve social media or dissemination or those that evaluate dissemination of nonresearch information (eg, multisource educational materials) to students or members of the public only, or without quantitative data on outcomes of interest, will be excluded. Screening will be carried out by 2 independent reviewers. Data extraction and quality assessment, using either the Cochrane tool for assessing risk of bias or the Newcastle-Ottawa Scale, will be completed by 2 independent reviewers. Outcomes of interest will be reported in 4 domains (reach, engagement, dissemination, and impact). Data synthesis will include quantitative comparisons using narrative text, tables, and figures. A meta-analysis of standardized pooled effects will be undertaken, and subgroup analyses will be applied, if appropriate. RESULTS: Searches and screening will be completed by the end of May 2023. Data extraction and analyses will be completed by the end of July 2023, after which findings will be synthesized and reported by the end of October 2023. CONCLUSIONS: This systematic review will summarize the evidence for the effectiveness of social media for the dissemination of research evidence to health and social care practitioners. The limitations of the evidence may include multiple outcomes or methodological heterogeneity that limit meta-analyses, potential risk of bias in included studies, and potential publication bias. The limitations of the study design may include potential insensitivity of the electronic database search strategy. The findings from this review will inform the dissemination practice of health and care research. TRIAL REGISTRATION: PROSPERO CRD42022378793; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=378793. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/45684.

Reconstructing the early evolution of Fungi using a six-gene phylogeny.

The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species. Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.

Zoospore ultrastructure and phylogenetic position of Phlyctochytrium aureliae Ajello is revealed (Chytridiaceae, Chytridiales, Chytridiomycota).

From forest soils in Scotland Phlyctochytrium aureliae was observed and brought into pure culture. Previously included in a molecular phylogenetic study of Chytridiales as Phlyctochytrium sp. KP 061, the organism groups with Phlyctochytrium planicorne, P. bullatum, Chytridium olla and C. lagenaria in the family Chytridiaceae. Thallus morphology and development as well as zoospore ultrastructure are detailed herein. The sporangium is epibiotic, spherical or subspherical, apophysate or non-apophysate, and ornamented with dentate enations. The overall zoospore ultrastructural features are consistent with the Group II type zoospore that characterizes family Chytridiaceae in the Chytridiales, although the zoospore also has two character states unique to this taxon: the MLC cisterna fenestrations are one-third to one-half the diameter of fenestrations in other Chytridiaceae zoospores and an accumulation of electron-dense material (a kinetosome-associated structure, or KAS) proximal to the kinetosome and non-flagellated centriole is extensive and unique. This study verifies that zoospore ultrastructure of P. aureliae zoospores places this species in the Chytridiales and Chytridiaceae, as indicated in a previous molecular phylogenetic study.