Enterocytozoon hepatopenaei sp. nov. (Microsporida: Enterocytozoonidae), a parasite of the black tiger shrimp Penaeus monodon (Decapoda: Penaeidae): Fine structure and phylogenetic relationships

A new microsporidian species, Enterocytozoon hepatopenaei sp. nov., is described from the hepatopancreas of the black tiger shrimp Penaeus monodon (Crustacea: Decapoda). Different stages of the parasite are described, from early sporogonal plasmodia to mature spores in the cytoplasm of host-cells. The multinucleate sporogonal plasmodia existed in direct contact with the host-cell cytoplasm and contained numerous small blebs at the surface. Binary fission of the plasmodial nuclei occurred during early plasmodial development and numerous pre-sporoblasts were formed within the plasmodium. Electron-dense disks and precursors of the polar tubule developed in the cytoplasm of the plasmodium prior to budding of early sporoblasts from the plasmodial surface. Mature spores were oval, measuring 0.7 × 1.1 μm and contained a single nucleus, 5-6 coils of the polar filament, a posterior vacuole, an anchoring disk attached to the polar filament, and a thick electron-dense wall. The wall was composed of a plasmalemma, an electron-lucent endospore (10 nm) and an electron-dense exospore (2 nm). DNA primers designed from microsporidian SSU rRNA were used to amplify an 848 bp product from the parasite genome (GenBank FJ496356). The sequenced product had 84% identity to the matching region of SSU rRNA from Enterocytozoon bieneusi. Based upon ultrastructural features unique to the family Enterocytozoonidae, cytoplasmic location of the plasmodia and SSU rRNA sequence identity 16% different from E. bieneusi, the parasite was considered to be a new species, E. hepatopenaei, within the genus Enterocytozoon.     

A new microsporidian parasite, Heterosporis saurida n. sp. (Microsporidia) infecting the lizardfish, Saurida undosquamis from the Arabian Gulf, Saudi Arabia: ultrastructure and phylogeny

A new microsporidian that infects the lizardfish Saurida undosquamis (Richardson, 1848) that are caught in the Arabian Gulf in Saudi Arabia is described here. This parasite invades the skeletal muscle of the abdominal cavity forming white, cyst-like structures containing numerous spores. The prevalence of the infection was 32·1% (135/420). The spores were oval to pyriform in shape and measured approximately 3·3 μm×2·0 μm. The developing spores were found within parasitophorous vacuoles. In mature spores, the polar filament was arranged into 5 coils in a row. Molecular analysis of the rRNA genes, including the ITS region, and phylogenetic analyses using maximum parsimony, maximum likelihood, and Bayesian inference were performed. The ultrastructural characteristics and phylogenetic analyses support the recognition of a new species, herein named Heterosporis saurida n. sp.     

A new microsporidian parasite, Potaspora morhaphis n. gen., n. sp. (Microsporidia) infecting the Teleostean fish, Potamorhaphis guianensis from the River Amazon. Morphological, ultrastructural and molecular characterization

A fish-infecting Microsporidia Potaspora morhaphis n. gen., n. sp. found adherent to the wall of the coelomic cavity of the freshwater fish, Potamorhaphis guianensis, from lower Amazon River is described, based on light microscope and ultrastructural characteristics. This microsporidian forms whitish xenomas distinguished by the numerous filiform and anastomosed microvilli. The xenoma was completely filled by several developmental stages. In all of these stages, the nuclei are monokaryotic and develop in direct contact with host cell cytoplasm. The merogonial plasmodium divides by binary fission and the disporoblastic pyriform spores of sporont origin measure 2.8+/-0.3 x 1.5+/-0.2 microm. In mature spores the polar filament was arranged into 9-10 coils in 2 layers. The polaroplast had 2 distinct regions around the manubrium and an electron-dense globule was observed. The small subunit, intergenic space and partial large subunit rRNA gene were sequenced and maximum parsimony analysis placed the microsporidian described here in the clade that includes the genera Kabatana, Microgemma, Spraguea and Tetramicra. The ultrastructural morphology of the xenoma, and the developmental stages including the spores of this microsporidian parasite, as well as the phylogenetic analysis, suggest the erection of a new genus and species.     

Myxidium volitans sp. nov., a parasite of the gallbladder of the fish, Dactylopterus volitans (Teleostei: Triglidae) from the Brazilian Atlantic coast--morphology and pathology

Myxidium volitans sp. nov. (Myxozoa: Myxidiidae) parasitizing the hypertrophied green-brownish gallbladder of the teleost Dactylopterus volitans, collected in the Atlantic coast near Niterói, Brazil was described based on ultrastructural studies. The spores were fusiform, sometimes slightly crescent-shaped on average 21.7 ± 0.3 μm (mean ± standard deviation) (n = 50) long and 5.6 ± 0.4 μm (n = 30) wide. The spore wall was thin and smooth, comprising two equally-sized valves joined by a hardly visible sutural ridge. Spores containing two pyriform polar capsules (PC) (5.0 ± 0.4 × 2.3 ± 0.3 μm) (n = 30) are situated in each extremity of the spore. The PC wall was composed of hyaline layer (0.20-0.29 μm thick) and by a thin external granular layer. Each PC contains a polar filament (PF) with irregular arrangements that was projected from its apical region to the bases of PC and coiled laterally from bases to the tip of PC. Some regular striations and S-like structures in the periphery of the PFs with four-five irregular sections were observed. Based on the spore morphology, ultrastructural differences and the specificity of the host we describe this parasite as a new myxosporidian, named M. volitans sp. nov.     

The arbuscular mycorrhizal Paraglomus majewskii sp. nov. represents a distinct basal lineage in Glomeromycota

Paraglomus majewskii sp. nov. (Glomeromycota) is described and illustrated. It forms single spores, which are hyaline through their life cycle, globose to subglobose, (35-)63(-78) μm diam, sometimes egg-shaped, 50-70 × 65-90 μm, and have an unusually narrow, (3.2-)4.6(-5.9) μm, cylindrical to slightly flared subtending hypha. The spore wall of P. majewskii consists of an evanescent, short-lived outermost layer, a laminate middle layer, and a flexible innermost layer, which adheres tightly to the middle layer. None of the spore wall layers stain in Melzer's reagent. In single-species cultures with Plantago lanceolata as the host plant P. majewskii formed arbuscular mycorrhizae staining violet in trypan blue. P. majewskii has been isolated from several, distant geographic regions and from different habitats. In phylogenetic analyses of partial nrDNA SSU and LSU sequences the fungus formed mono-phyletic group with Paraglomus species; however it represents a well separated distinct lineage. Its nrDNA sequences are highly similar to in planta arbuscular mycorrhizal fungal sequences from different habitats in Spain and Ecuador.     

Maullinia ectocarpii gen. et sp. nov. (Plasmodiophorea), an intracellular parasite in Ectocarpus siliculosus (Ectocarpales, Phaeophyceae) and other filamentous brown algae

An obligate intracellular parasite infecting Ectocarpus spp. and other filamentous marine brown algae is described. The pathogen forms an unwalled multinucleate syncytium (plasmodium) within the host cell cytoplasm and causes hypertrophy. Cruciform nuclear divisions occur during early development. Mature plasmodia become transformed into single sporangia, filling the host cell completely, and then cleave into several hundred spores. The spores are motile with two unequal, whiplash-type flagella inserted subapically and also show amoeboid movement. Upon settlement, cysts with chitinous walls are formed. Infection of host cells is accomplished by means of an adhesorium and a stachel apparatus penetrating the host cell wall, and injection of the cyst content into the host cell cytoplasm. The parasite is characterized by features specific for the plasmodiophorids and is described as a new genus and species, Maullinia ectocarpii.     

Description of Hyalinocysta expilatoria n. sp., a microsporidian parasite of the blackfly Odagmia ornata

Hyalinocysta expilatoria n. sp. is described from a larva of Odagmia ornata collected in Sweden. Infection was restricted to the adipose tissue which was transformed into a syncytium. The earliest stage observed was diplokaryotic merozoites, which mature directly into diplokaryotic sporonts. Each sporont produces a sporophorous vesicle (pansporoblast), which persists, also enclosing mature spores. Usually nuclear divisions result in a plasmodium with 8 nuclei, which fragments into 8 sporoblasts, each of which develops into a spore without further division. Occasionally an aberrant number of spores (2, 4, 6) is formed. The spores are pyriform with a flattened area at the posterior pole. Spores in sporophorous vesicles with 8 spores are 4.0–6.0 μm long, in vesicles with 4 spores 4.0–5.0 μm, and in vesicles with 2 spores 7.0–8.0 μm. In some vesicles the spores develop asynchronously, and 2, 4, or 6 mature spores are found together with 6, 4, or 2 immature. There was also a small number of vesicles with supernumerary spores, less than 8 normally developed. The 325–350 nm thick spore wall is composed of three layers. The polar filament is anisofilar with 7 coils in a single layer. The anterior 5–6 coils are wide, the posterior 2-1 thin. The angle of tilt of the anterior filament coil is approximately 50°. The spore has a single nucleus. The sporophorous vesicle is delimited by a thin membrane, also visible in haematoxylin stained preparations. Vesicles with mature spores are void of metabolic inclusions.     

Maullinia ectocarpii gen. et sp. nov. (Plasmodiophorea), an Intracellular Parasite in Ectocarpus siliculosus (Ectocarpales, Phaeophyceae) and other Filamentous Brown Algae

An obligate intracellular parasite infecting Ectocarpus spp. and other filamentous marine brown algae is described. The pathogen forms an unwalled multinucleate syncytium (plasmodium) within the host cell cytoplasm and causes hypertrophy. Cruciform nuclear divisions occur during early development. Mature plasmodia become transformed into single sporangia, filling the host cell completely, and then cleave into several hundred spores. The spores are motile with two unequal, whiplash-type flagella inserted subapically and also show amoeboid movement. Upon settlement, cysts with chitinous walls are formed. Infection of host cells is accomplished by means of an adhesorium and a stachel apparatus penetrating the host cell wall, and injection of the cyst content into the host cell cytoplasm. The parasite is characterized by features specific for the plasmodiophorids and is described as a new genus and species, Maullinia ectocarpii.     

Ultrastructural characteristics and small subunit ribosomal DNA sequence of Vairimorpha cheracis sp. nov., (Microspora: Burenellidae), a parasite of the Australian yabby, Cherax destructor (Decapoda: Parastacidae)

This is the first record of a species of Vairimorpha infecting a crustacean host. Vairimorpha cheracis sp. nov. was found in a highland population of the Australian freshwater crayfish, Cherax destructor. The majority of spores and earlier developmental stages of V. cheracis sp. nov. were found within striated muscle cells of the thorax, abdomen, and appendages of the crayfish. Only octosporoblastic sporogony within sporophorous vesicles (SPVs) was observed. Diplokaryotic sporonts separated into two uninucleate daughter cells, each of which gave rise to four sporoblasts in a rosette-shaped plasmodium, so that eight uninucleate spores were produced within the persistent ovoid SPV. Ultrastructural features of stages in the octosporoblastic sequence were similar to those described for Vairimorpha necatrix, the type species. Mature spores were pyriform in shape and averaged 3.4x1.9 microm in dimensions. The anterior polaroplast was lamellar in structure, and the posterior polaroplast vesicular. The polar filament was coiled 10-12 times, lateral to the posterior vacuole. The small subunit ribosomal DNA (SSU rDNA) of V. cheracis sp. nov. was sequenced and compared with other microsporidia. V. cheracis sp. nov. showed over 97% sequence identity with Vairimorpha imperfecta and five species of Nosema, and only 86% sequence identity with V. necatrix. The need for a taxonomic revision of the Nosema/Vairimorpha group of species is discussed.     

Isolation, characterization, and polyaromatic hydrocarbon degradation potential of aerobic bacteria from marine macrofaunal burrow sediments and description of Lutibacterium anuloederans gen. nov., sp. nov., and Cycloclasticus spirillensus sp. nov.

Two new polyaromatic hydrocarbon-degrading marine bacteria have been isolated from burrow wall sediments of benthic macrofauna by using enrichments on phenanthrene. Strain LC8 (from a polychaete) and strain M4-6 (from a mollusc) are aerobic and gram negative and require sodium chloride (>1%) for growth. Both strains can use 2- and 3-ring polycyclic aromatic hydrocarbons as their sole carbon and energy sources, but they are nutritionally versatile. Physiological and phylogenetic analyses based on 16S ribosomal DNA sequences suggest that strain M4-6 belongs to the genus Cycloclasticus and represents a new species, Cycloclasticus spirillensus sp. nov. Strain LC8 appears to represent a new genus and species, Lutibacterium anuloederans gen. nov., sp. nov., within the Sphingomonadaceae. However, when inoculated into sediment slurries with or without exogenous phenanthrene, only L. anuloederans appeared to sustain a significant phenanthrene uptake potential throughout a 35-day incubation. In addition, only L. anuloederans appeared to enhance phenanthrene degradation in heavily contaminated sediment from Little Mystic Cove, Boston Harbor, Boston, Mass.     

Enterospora canceri n. gen., n. sp., intranuclear within the hepatopancreatocytes of the European edible crab Cancer pagurus

Only 1 genus (Nucleospora) within 1 family (Enterocytozoonidae) of the Microsporidia contains species that are parasitic within the nuclei of their host cells; to date, all described intranuclear Nucleospora spp. parasitise fish. This study describes the first intranuclear microsporidian parasite of an invertebrate, the European edible crab Cancer pagurus L. (Decapoda: Cancridae). Infected crabs displayed no obvious external signs, and maximum apparent prevalence of infection within a monthly sample was 3.45%. Infected hepatopancreatic tubules were characterised by varying numbers of hypertrophic and eosinophilic nuclei within epithelial cells. Parasite stages appeared as eosinophilic granular accumulations causing margination of host chromatin. In advanced cases, the tubule epithelia degenerated, with parasites and sloughed epithelial cells appearing in tubule lumens. All life stages of the parasite were observed within host nuclei. Uninucleate meronts were not detected, although binucleate stages were observed. Multinucleate plasmodia (sporogonal plasmodia) contained up to 22 nuclei in section, and late-stage plasmodia contained multiple copies of apparatus resembling the polar filament and anchoring disk, apparently associated with individual plasmodial nuclei. As such, aggregation and early assembly of sporoblast components took place within the intact sporogonial plasmodium, a feature unique to the Enterocytozoonidae. Liberation of sporoblasts from plasmodia or the presence of liberated sporoblasts was not observed in this study. However, large numbers of maturing and mature spores (measuring 1.3 +/- 0.02 x 0.7 +/- 0.01 microm) were frequently observed in direct contact with the host nucleoplasm. Considering the shared features of this parasite with microsporidians of the family Enterocytozoonidae, and the unique presence of this parasite within the nucleoplasm of decapod crustacean hepatopancreatocytes, this parasite (Enterospora canceri) is proposed as the type species of a new genus (Enterospora) of microsporidian. Molecular taxonomic work is now required, comparing Enterospora to Enterocytozoon and Nucleospora, the 2 other genera within the Enterocytozoonidae.     

Interrenal disease in bluegills (Lepomis macrochirus) caused by a new genus and species of myxozoan

A myxozoan species not matching with any described genus was encountered in a survey of fish parasites of freshwater fishes in New York. The parasite was observed in the kidney tubules of bluegill sunfish Lepomis macrochirus. A new genus is described to accommodate Acauda hoffmani n. gen., n. sp., which exhibits pyriform spores with longitudinal ridges and polar capsules perpendicular to the sutural plane. Spores measure 17.9-21.8 μm long and 6.9-11.0 μm wide, with spore valves each with 11-12 ridges. Two polar capsules measure 9.4-12.5 μm long by 2.9-4.0 μm wide and contain a filament coiled 10-15 times. Phylogenetic analysis places A. hoffmani n. gen., n. sp. as a sister to a Myxobilatus and a Hoferellus species. The clustering of these 3 similar genera in the larger 'freshwater' clade of myxozoans does not support their inclusion in the Sphaerosporidae but instead supports the distinct status of the Myxobilatidae Shulman 1953.     

Developmental stages of Hepatozoon hemprichii sp. nov. infecting the skink Scincus hemprichii and the tick Hyalomma impeltatum from Saudi Arabia

The life cycle of Hepatozoon hemprichi n. sp. is described; the vertebrate host is Scincus hemprichii and it is vectored by Hyalomma impeltatum. Erythrocytic stages of 18 ± 1.8 × 4 ± 0.8 μm developed in the hemocoel of ticks to sporozoites within 16-18 days. Schizogony occurred in the liver parenchyma and the endothelial cells of blood capillaries in lung and spleen. Mature schizonts measuring 27 ± 3.11 × 20.13 ± 3.0 μm produced 28 merozoites (on average). The merozoites were 13 ± 1.21 × 1.21 ± 0.72 μm with nuclei 5 ± 0.65 × 2.1 ± 0.51 μm. Syzygy and differentiation of gamonts took place in tick's hemocoel up to the third day post-infection (PI). The microgamont (16 ± 0.31 × 18 ± 0.42 μm) produced 4, uniflagellated microgametes at 4-5 days PI. The microgamete measured 15.2 ± 0.31 μm while the flagellum was always at least 26 μm. The macrogamete was very large in size (31 ± 3.11 μm) with a central nucleus. After fertilization, (5-6 days PI) zygotes developed into oocysts (55 ± 3.41 × 52 ± 4.11 μm) in which repeated mitotic divisions with centripetal invaginations occurred; each contained 18 banana-shaped sporozoites, 13.61 ± 0.8 × 1.2 ± 0.31 μm in size. Experimental transmission was successfully carried out by oral administration or by intra-peritoneal inoculation of the infective stages (sporozoites) to uninfected skinks and led to the appearance of blood stages after 5 wk and 4 wk, respectively.     

浮霉菌门严格厌氧产氢细菌(Thermopirellula anaerolimosa)的分离及其生理特性

[目的]厌氧颗粒污泥中含有大量未知微生物资源,利用低浓度底物及添加抗生素的培养基进行厌氧发酵细菌的筛选,并对分离菌株进行生理生化特性研究.[方法]利用系列稀释法及亨盖特厌氧滚管技术从制糖废水厌氧处理反应器的颗粒污泥中分离到一株高温厌氧产氢细菌VM20-7T,通过16S rRNA基因序列同源性确定其系统发育地位.[结果]菌株VM20-7T为高温、严格厌氧、革兰氏阴性梨形细菌,细胞大小为(0.7-2.0)μm×(0.7-2.0) μm,不运动,不产芽胞.其生长温度范围为35℃-50℃(最适温度45℃),pH范围为6.0-8.3(最适pH7.0-7.5),NaCl耐受范围为0％-0.5％(w/v,最适浓度0％).菌株VM20-7T可利用葡萄糖、麦芽糖、核糖等多种糖类为唯一碳源生长,葡萄糖发酵终产物是乙酸和H2.该菌株不利用硝酸盐、硫酸盐等作为电子受体生长.G+C含量为60.9 mol％,16S rRNA基因序列同源性显示菌株属于浮霉菌门,但与已培养菌株的同源性较低,与梨形菌属一红小梨形菌属-芽殖小小梨形菌属(Pirellula-Rhodopirellul -Blastopirellula,PRB)分支的亲缘关系最近,但序列相似性也仅为82.7％-84.3％.[结论]利用低浓度糖类并添加抗生素分离厌氧颗粒污泥中的微生物,获得了浮霉菌门首例严格厌氧细菌VM20-7T.生理生化特性和系统发育分析显示,菌株VM20-7T为浮霉菌目的新属新种,命名为Thermopirellula anaerolimosa.该菌株的菌种保藏号为CGMCC 1.5169T=JCM 17478T=DSM 24165T.     

A mid-Cretaceous trichomycete,Priscadvena corymbosa gen. et sp. nov., in Burmese amber

Priscadvena corymbosa gen. et sp. nov., is described from thalli and sporangia emerging from the oral cavity of a click beetle (Coleoptera: Elateridae) in mid-Cretaceous Burmese amber. The fossil contains several features unknown in extant Trichomycetes including a click beetle (Coleoptera: Elateridae) host, spiny, aerial thalli with the entire thallus bearing numerous small uninucleate globular spores and stalks attached to the oral cavity of its host. Based on these features, P. corymbosa gen. et sp. nov. is placed in a new family, Priscadvenaceae fam. nov., and new order, Priscadvenales ord. nov. The new morphological and behavioral features of the fossil add to the diversity of the trichomycetes as currently defined.     

Mobilicoccus pelagius gen. nov., sp. nov. and Piscicoccus intestinalis gen. nov., sp. nov., two new members of the family Dermatophilaceae, and reclassification of Dermatophilus chelonae (Masters et al. 1995) as Austwickia chelonae gen. nov., comb. nov

Two Gram-positive bacteria, designated strains Aji5-31(T) and Ngc37-23(T), were isolated from the intestinal tracts of fishes. 16S rRNA gene sequence analysis indicated that both strains were related to the members of the family Dermatophilaceae, with 95.6-96.9% 16S rRNA gene sequence similarities. The family Dermatophilaceae contains 2 genera and 3 species: Dermatophilus congolensis, Dermatophilus chelonae and Kineosphaera limosa. However, it has been suggested that the taxonomic position of D. chelonae should be reinvestigated using a polyphasic approach, because the chemotaxonomic characteristics are not known (Stackebrandt, 2006; Stackebrandt and Schumann, 2000). Our present study revealed that strains Aji5-31(T), Ngc37-23(T) and D. chelonae NBRC 105200(T) should be separated from the other members of the family Dermatophilaceae on the basis of the following characteristics: the predominant menaquinone of strain Aji5-31(T) is MK-8(H(2)), strain Ngc37-23(T) possesses iso- branched fatty acids as major components, and the menaquinone composition of D. chelonae is MK-8(H(4)), MK-8 and MK-8(H(2)) (5 : 3 : 2, respectively). On the basis of these distinctive phenotypic characteristics and phylogenetic analysis results, it is proposed that strains Aji5-31(T) and Ngc37-23(T) be classified as two novel genera and species of the family Dermatophilaceae. The names are Mobilicoccus pelagius gen. nov., sp. nov. and Piscicoccus intestinalis gen. nov., sp. nov., and the type strains are Aji5-31(T) (=NBRC 104925(T) =DSM 22762(T)) and Ngc37-23(T) (=NBRC 104926(T) =DSM 22761(T)), respectively. In addition, D. chelonae should be reassigned to a new genus of the family Dermatophilaceae with the name Austwickia chelonae gen. nov., comb. nov.     

Entomophthora brevinucleata sp. nov. [Zygomycetes,Entomophthoraceae], a pathogen of gall midges [Dip.: Cecidomyiidae]

Entomophthora brevinucleata, a fungal pathogen of gall midges, is described. The species occurs on at least 3 host species, including the wheat blossom midgeSitodiplosis mosellana Géhin andMycodiplosis sp.E. brevinucleata produces rhizoids, either monohyphal or comprising bundles of a few hyphae, without holdfasts. The hyphal bodies are subspherical with mean dimensions of 27.5×22.1 μm. The primary conidia are campanulate with mean dimensions from individual hosts of 11.2–18.9×8.7–15.8 μm. They contain 3–13 nuclei with a mean diameter of between 2.7 and 3.7 μm stained with lactophenol-aceto-orcein. The secondary conidia are of similar shape but smaller. Cystidia and resting spores were not observed.     

Pseudocollinia brintoni gen. nov., sp. nov. (Apostomatida: Colliniidae), a parasitoid ciliate infecting the euphausiid Nyctiphanes simplex

A novel parasitoid ciliate, Pseudocollinia brintoni gen. nov., sp. nov. was discovered infecting the subtropical sac-spawning euphausiid Nyctiphanes simplex off both coasts of the Baja California peninsula, Mexico. We used microscopic, and genetic information to describe this species throughout most of its life cycle. Pseudocollinia is distinguished from other Colliniidae genera because it exclusively infects euphausiids, has a polymorphic life cycle, and has a small cone-shaped oral cavity whose left wall has a field of ciliated kinetosomes and whose opening is surrounded on the left and right by 2 'oral' kineties (or ciliary rows) that terminate at its anterior border. Two related species that infect different euphausiid species from higher latitudes in the northeastern Pacific Ocean, Collinia beringensis Capriulo and Small, 1986, briefly redescribed herein, and Collinia oregonensis Gómez-Gutiérrez, Peterson, and Morado, 2006, are transferred to the genus Pseudocollinia. P. brintoni has between 12 and 18 somatic kineties, and its oral cavity has only 2 oral kineties, while P. beringensis comb. nov. has more somatic kineties, including 3 oral kineties. P. oregonensis comb. nov. has an intermediate number of somatic kineties. P. beringensis comb. nov. also infects Thysanoessa raschi (a new host species). SSU rRNA and cox1 gene sequences demonstrated that Pseudocollinia ciliates are apostome ciliates and that P. brintoni is different from P. beringensis comb. nov. High densities of rod-shaped bacteria (1.7 μm length, 0.2 to 0.5 μm diameter) were associated with P. brintoni. After euphausiid rupture, high concentrations of P. brintoni and bacteria cluster to form 3 to 6 cm long filaments where tomites encyst and transform to the phoront stage; this is a novel place for encystation. P. brintoni may complete its life cycle when the euphausiids feed on these filaments.     

Atradidymella muscivora gen. et sp. nov. (Pleosporales) and its anamorph Phoma muscivora sp. nov.: A new pleomorphic pathogen of boreal bryophytes

During a survey of bryophilous fungi from boreal and montane habitats, 12 isolates of a hitherto unknown plant pathogenic member of the Pleosporales were recovered from Aulacomnium palustre, Hylocomium splendens, and Polytrichum juniperinum, and described as Atradidymella muscivora gen. et sp. nov. Atradidymella is characterized by minute, unilocular, setose pseudothecia having 2-3 wall layers; brown, fusiform, 1-septate ascospores; and a Phoma anamorph. The genus is distinguished from all other pleosporalean genera with brown, fusiform ascospores on the basis of ascospore and pseudothecium morphology and a highly reduced stroma that is localized within a single host cell. Atradidymella muscivora is distinguished by its minute pseudothecia (<115 μm) and ascospores that are slightly allantoid and constricted at the septum with the upper cell often wider than the lower. Its anamorph, Phoma muscivora sp. nov., is morphologically distinguishable from P. herbarum in having smaller conidia. Parsimony analysis of the ITS rDNA region indicates A. muscivora has affinities to the Phoma-Ascochyta-Didymella clade that is sister to the Phaeosphaeriaceae within the Pleosporales.