Henneguya cynoscioni sp. n. (Myxosporea: Bivalvulida), an agent of severe cardiac lesions in the spotted seatrout, Cynoscion nebulosus (Teleostei: Sciaenidae)

A new myxosporean species, Henneguya cynoscioni sp. n., is described from the spotted seatrout, Cynoscion nebulosus (Cuvier) (Sciaenidae) as a causative agent of cardiac henneguyosis. This new myxosporean species is characterized by the morphology of spores and the sequence of SSU rDNA. Examination of 227 spotted seatrout from four South Carolina estuaries in 2008-2010 revealed a 33.5% total prevalence of H. cynoscioni. Henneguya cynoscioni produces lesions in the bulbus arteriosus, its specific site of infection. The severity of lesions and their impact on the bulbus arteriosus is proportional to the number of plasmodial stages developing in this segment of the heart, being most pronounced in host reaction directed against spores liberated from plasmodia.     

Neoechinorhynchus (Neoechinorhynchus) zabensis sp. n. (Acanthocephala: Neoechinorhynchidae) from freshwater fish in northern Iraq

Neoechinorhynchus (Neoechinorhynchus) zabensis sp. n. (Acanthocephala: Neoechinorhynchidae) is described from Capoeta damascina (Valenciennes, 1842) (type host) and Capoeta trutta (Heckel, 1843) in the Greater and Lesser Zab Rivers, northern Iraq. The new species is unique among all other species of the genus by its characteristic paired para-vaginal muscular appendage and fragmented giant nuclei in the lemnisci. Eleven of the other 88 valid species of Neoechinorhynchus and N. zabensis have middle and posterior hooks of equal length. However, N. zabensis is distinguished from the others by size of trunk, proboscis, proboscis hooks and lemnisci, number of giant nuclei, position of female gonopore, and geographical and host distribution. It is also distinguished from six other species of Neoechinorhynchus previously reported from Iraq. Other distinguishing features are also included.     

Detection of airborne inoculum of Leptosphaeria maculans and Pyrenopeziza brassicae in oilseed rape crops by polymerase chain reaction (PCR) assays

The potential use of DNA-based methods for detecting airborne inoculum of Leptosphaeria maculans and Pyrenopeziza brassicae , both damaging pathogens of oilseed rape, was investigated. A method for purifying DNA from spores collected using Hirst-type spore samplers and detecting it using polymerase chain reaction (PCR) assays is described. For both pathogens, the sensitivities of the DNA assays were similar for spore-trap samples and pure spore suspensions. As few as 10 spores of L. maculans or P. brassicae could be detected by PCR and spores of both species could be detected against a background of spores of six other species. The method successfully detected spores of P. brassicae collected using spore traps in oilseed rape crops that were infected with P. brassicae. Leptosphaeria maculans spores were detected using spore traps on open ground close to L. maculans -infected oilseed rape stems. The potential use of PCR detection of airborne inoculum in forecasting the diseases caused by these pathogens is discussed.     

Genetic analysis of factors for resistance to downy mildew (Bremia lactucae) in species of lettuce (Lactuca sativa and L. serriola)

Simultaneous genetic analysis of resistance in species of lettuce (Lactuca sativa and L. serriola) and a virulence in Bremia lactucae were made to characterize the genetic basis of resistance to downy mildew in 11 host cultivars and accessions. Four new downy mildew resistance genes (Dm13, Dm14, Dm15 and Dm16) were characterized. Other resistance phenotypes were conditioned by combinations of these or previously described Dm genes. New resistance genes, Dm 16 (from LSE/18), Dm14 (from Gelber Winterkonig) and Dm15 (from PIVT 1309), mapped to Dm linkage group I (Dm1, Dm2, Dm3 and Dm6) while Dm13 from Pennlake segregated independently of the three previously characterized linkage groups and therefore belongs to a fourth linkage group. Characterization of new resistance genes requires simultaneous consideration of host and pathogen genetics.     

Review of the sequential development of Loma salmonae (Microsporidia) based on experimental infections of rainbow trout (Oncorhynchus mykiss) and Chinook salmon (O. tshawytscha)

Loma salmonae is a common gill parasite of salmonids, and essentially all species in the genus Oncorhynchus are susceptible. Infections occur in both fresh and salt water. Loma salmonae is directly transmissible by ingestion of spores or infected tissue. The parasite infects the wall of blood vessels of various organs, but the gill is the primary site of infection. Initial infection occurs in the intestine, and xenomas are easily detected in the gills by standard histology at 4-6 wk post-exposure. A few presporogonic stages of the parasite are found in the heart endothelium prior to xenoma formation in the gills. Ultrastructure studies of early infections demonstrated that wandering blood cells transport the meronts to the gills, and that merogony occurs in pillar cells and other cells underlying the gill endothelium. Xenomas develop in these cells, resulting in hypertrophied host cells filled with spores. Xenomas ultimately rupture, and are associated with severe inflammation in which free spores are found in macrophages. The parasites are most pathogenic during this phase of the infection, resulting in severe vasculitis and clinical disease. Both rainbow trout (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus ishawytscha) recover from infections, but free spores persist in kidney and spleen phagocytes for many months after xenomas are absent in Chinook salmon. Fish that have recovered from the infection show strong immunity against the parasite, lasting up to 1 year. Fish are susceptible to infection by other routes of exposure by spores; co-habitation, anal gavage, and intramuscular, intraperitoneal and intravascular injection. Autoinfection probably occurs following release of spores in blood vessels after xenomas rupture. The optimal temperature for L. salmonae infections is 15-17 degrees C, with a permissive range of 11-20 degrees C.     

Phylogeny of Coccomyxa (Myxosporea: Myxidiidae) spp. with the description of a new species from Bathygobius cyclopterus (Gobiidae) in the northern Red Sea

Two species of Coccomyxa Léger et Hesse, 1907, one of the least studied myxosporean genera, are reported from shallow coastal waters in the Gulf of Eilat, Red Sea, Israel. A new species, Coccomyxajirilomi sp. n. is described from the spotted frillgoby Bathygobius cyclopterus (Valenciennes) (Gobiidae). It forms polysporous plasmodia that invade the liver and form packed clusters inside the bile ductules. Plasmodia also occur in the bile ducts and gall bladder of the host, attached to the epithelial lining or free floating in the bile. Infected hepatic bile ductules packed with plasmodia were partially occluded, with evidence of cholestasis, periductular fibrosis and pericholangitis. The mature spore is ellipsoid, has smooth valves and contains a single polar capsule with the polar filament arranged in 4-5 oblique coils. Spore dimensions are 9.0-11.3 x 5.0-7.0 microm. A second species, Coccomyxa sp., with smaller 7.6-9.6 x 4.2-5.2 microm and more delicate spores, was found in the gall bladder of the rippled rockskipper, Istiblennius edentulus (Forster et Schneider) (Blenniidae). The small subunit (SSU) rDNA sequence analysis of both Coccomyxa species suggests that they are closely related to members of the genera Myxidium, Zschokkella and Auerbachia, whose members infect the gall bladder of marine fish.     

Kudoa dianae sp. n. (Myxosporea: Multivalvulida), a new parasite of bullseye puffer, Sphoeroides annulatus (Tetraodontiformes: Tetraodontidae)

A new multivalvulid myxosporean species, Kudoa dianae sp. n., is described from bullseye puffer, Sphoeroides annulatus (Jenyns) (Tetraodontiformes: Tetraodontidae). Plasmodia develop in extramuscular sites, in the wall of oesophagus and less frequently on mesenteries. Mature spores can reach lumen of the digestive tract directly by disruption of plasmodial wall or via macrophage transport to the oesophageal epithelium. New species is characterised by morphology of spores and by the complete sequence of SSU rRNA gene that differs from all hitherto known sequences of Kudoa species. Spore morphology (moderate-sized, simple non-ornate spores, quadrate in apical view) clusters with that of Kudoa scienae, K. cerebralis, K. chilkaensis, K. leiostomi, K. finduli, K. cascasia and K. ovivora. Analysis of phylogenetic relationships (using SSU rRNA gene sequences) among five Kudoa species, the molecular data of which are available thus far, revealed that K. dianae is distinguishable from these five species and that its closest relation is with K. miniauiriculata.     

Electron microscopic study of a new microsporean Microsporidium epithelialis sp. n. infecting Tubifex sp. (Oligochaeta)

The cytology of a new microsporean parasite Microsporidium epithelialis sp. n. from the intestinal epithelial cells of the freshwater oligochaete Tubifex sp. (Tubificidae) is described. The microsporean occurred together with an actinosporean of the genus Triactinomyxon, which was found between the epithelial cells. The merogonic and sporogonic stages (mature spores included) of the microsporean parasite are monokaryotic. An individual sporophorous vesicle surrounds each spore. The fixed and stained spore has an average dimension of 1.9-2.5 x 0.9-1.2 microm. The spores are oval with a characteristic surface layer, showing ornamentation-like projections, which are in close contact to the exospore. A short polar filament forming three to four coils traverses the polaroplast with two lamellar layers. The ultrastructure and other characteristic features of this microsporean parasite are distinct from those of the microsporean species described so far from oligochaetes.     

Brain thelohanellosis due to Thelohanellus oculileucisci (Myxozoa: Myxosporea) in Gobio gobio

The first case of a Thelohanellus infection in the brain of gudgeons (Gobio gobio) is described. The infection was found on three localities in southern Bohemia, Czechoslovakia. The spores measured 13.2-14.4 x 6.3-7.1 micron. The reasons are discussed for which the species was identified as T. oculileucisci Trojan, 1909.     

Two species of philometrid nematodes (philometridae) from marine fishes off Japan, including Philometroides branchiostegi sp. n. from Branchiostegus japonicus (malacanthidae)

Gravid females of two species of philometrid nematodes (Philometridae) were collected from marine perciform fishes in Japanese waters, mainly from the southern Sea of Japan. Based on light microscopy and scanning electron microscopy examinations, the previously described but poorly known species Philometra cryptocentri Yamaguti, 1961 is redescribed from specimens recovered from the abdominal cavity of Acanthogobius flavimanus (Temminck et Schlegel), Pterogobius elapoides (Günther) and P. zonoleucus Jordan et Snyder (all Gobiidae) (all new host records); the number (14) and arrangement of cephalic papillae in this species are described for the first time. The new species, Philometroides branchiostegi sp. n. from head tissues of Branchiostegus japonicus (Houttuyn) (Malacanthidae), based on a single specimen, is mainly characterized by the embossment of the entire body except for the cephalic end, presence of four submedian pairs of large cephalic papillae of external circle and two small lateral single papillae of internal circle, pair of large papilla-like caudal projections, the oesophagus with a distinct anterior inflation, by a markedly small body (length about 18 mm) and the larvae 306-465 microm long.     

Morphology and ultrastructure of Sphaeromyxa noblei sp. n. (Myxozoa), parasite of Heteroclinus whiteleggii (Pisces) from Australian New South Wales coast

A new species, Sphaeromyxa noblei sp. n., is described from Heteroclinus whiteleggii (Perciformes: Clinidae), a marine fish from the coast of New South Wales in Australia. This raises the number of Sphaeromyxa species to 38; their list is presented. The species is characterised by a layer of branched glycostyles, which is about 2.4 microm thick and is a feature rather unique in Myxosporea. Pansporoblasts form one or two spores. The study of ultrastructure of this species and of those described to date result in recognition of a combination of patterns characterising the genus: plasmodia have marked surface projections, the endoplasm is full of vacuoles larger than in any other myxosporean genus, and contains a special kind of cells, the lobocytes. Sections through polar capsule reveal different appearance of subsequent stretches of the polar filament unlike in other Myxosporea.     

The life cycle of Echinostoma bolschewense (Kotova, 1939) (Trematoda: Echinostomatidae)

The life cycle of E. bolschewense, the species with 37 collar spines and closely related to E. revolutum, was experimentally studied. The following developmental stages are described: mother and daughter rediae, cercaria, metacercaria, and adult. The freshwater prosobranchiate snail Viviparus contectus was found to be the first intermediate host in nature. Under experimental conditions, the miracidia developed in V. contectus. They did not, however, penetrate into Bithynia tentaculata or into any of the pulmonate snails tested. The cercariae encysted in various Prosobranchia and Pulmonata. Adult worms were commonly obtained from hamsters (Mesocricetus auratus) and only exceptionally from chickens (Gallus gallus f. dom.). The species studied is considered to be conspecific with Cercaria bolschewensis described by Kotova (1939).     

Studies on Botrytis spp. occurring on onions (Allium cepa) and leeks (Allium porrum)

Botrytis byssoidea (mycelial neck rot) was more prevalent than B. allii (sclerotial neck rot) on the leaves of field onions and the bulbs of stored onions grown in some of the areas where onions or onions and leeks had previously been grown sequentially.
B. byssoidea and B. porri were also isolated from leeks. Spores of B. allii, B. byssoidea (from onions and leeks), B. porri , and B. squamosa caused infection of seedlings of salad (green) and bulb onions.
Inoculation with B. squamosa spores caused severe infection of seedling leaves, but inoculation with mycelial discs caused little damage to onion bulb tissue. By comparison, mycelial discs of the remaining species were highly pathogenic to bulbs.
The practical implications of disease transfer of certain of these species between onions and leeks are discussed.     

Myxobolus intrachondrealis sp. n. (Myxosporea: Myxobolidae), a parasite of the gill cartilage of the common carp, Cyprinus carpio

A species not identifiable with any of the about 23 Myxobolus species recorded from the common carp so far, was detected in the gills of one- and two-summer-old specimens of the common carp ((Cyprinus carpio L.) cultured in pond farms in Hungary. The strictly tissue-specific plasmodia of the parasite were located, surrounded by hyaline cartilage cells, in the chondrous substance of the terminal parts of the gill arches and in the cartilage structure ventrally connecting the gill arches. The spores of the parasite described as Myxobolus intrachondrealis sp. n. developed in globular or ellipsoidal plasmodia measuring 300-600 microm. By their elongated ellipsoidal shape and similarly elongated polar capsules the spores were well distinguishable from the hitherto described Myxobolus species parasitic in the common carp and also from the cartilage-parasitic Myxobolus species of other fishes.     

A species of Unguicularia on oilseed rape, and its importance in studies of the epidemiology of light leaf spot (Pyrenopeziza brassicae)

Apothecia of a species of Unguicularia were found on fallen leaves of oilseed rape from November 1989 to April 1990, and from January to July 1991. On the basis of the limited literature on this genus, these apothecia were tentatively identified as Unguicularia cfr. raripila, a species not previously reported in the UK, or on oilseed rape. Although saprophytic, it is of significance in oilseed rape crops, as its ascospores are similar in size and shape to those of the important pathogen Pyrenopeziza brassicae, the cause of light leaf spot. The ascospores of both species can be dispersed either as single spores or in groups, although those of U. cfr. raripila are more often dispersed in groups. Due to confusion in distinguishing the ascospores of these two species, it is likely that studies of the epidemiology of light leaf spot using spore samplers have overestimated the numbers of ascospores of P. brassicae dispersed, and hence their potential contribution to epidemics. Apothecia of U. cfr. raripila were abundant in the spring of both 1990 and 1991, but those of P. brassicae were much more rare. The species of Unguicularia is described.     

Acolpenteron australe sp. n. (Dactylogyridae:Dactylogyrinae), a new species from the ureters of Percichthys trucha (Perciformes:Percichthyidae) in Patagonia (Argentina)

Acolpenceron australe sp. n. (Dactylogyridae, Dactylogyrinae) is described from ureters and renal tubules of Percichthys trucha (Cuvier et Valenciennes) (Perciformes, Percichthyidae) from Andean Patagonian lakes. The new species has a haptor with 14 hooks, with shanks comprised of two subunits. It has overlapped intercaecal gonads, male copulatory organ as a sclerotized tube with one counterclockwise coil and a J-shaped accessory piece. It differs from the other species of Acolpenteron by having a non-forked accessory piece. This is the first monogenean species described from a percichthyid host in South America.     

The host range of Polymyxa betae in Britain

The host range of Polymyxa betae on common arable weed species in Britain was determined by growing plants in naturally infested soil and examining their root systems for the presence of resting spores (cystosori). Of the 24 species tested, only Atriplex patula and Chenopodium album of the Chenopodiaceae, and Silene alba of the Caryophyllaceae, were found to be heavily infected. S. alba is a newly recorded host species for Polymyxa. The host specificity of isolates of P. betae from Beta vulgaris, C. album and A. patula was investigated by observing which of 11 test plants could be infected by the isolates obtained from this soil. Three main biotypes of P. betae appeared to be distinguishable: one which was able to infect all chenopodiaceous species; one which had a narrower host range; and one which was able to infect S. alba. The role of weed species in the epidemiology of rhizomania is discussed.