Unicauda magna sp.n. (Protozoa: Myxozoa): a new myxozoan from the fin tissues of the fathead minnow, Pimephales promelas Rafinesque

Abstract. Unicauda magna sp.n. (Protozoa: Myxozoa) was found in hatchery-raised fathead minnows, Pimephales promelas (Cyprinidae) from Pennsylvania. A large number of whitish-coloured cysts were located in the tissues of the pectoral, pelvic and caudal fins of infected fish. Spore dimensions (in μm) based on 30 measurements (10 spores/cyst) included the following: total length, 109.6 (75–170); spore body length, 15.5 (14–17); spore body thickness, 12.1 (10–13); spore body width, 13.2 (12–14.5); tail length, 94.1 (60–154); polar capsule lengths, 8.6 (7.5–9.5); polar capsule width 4.1 (3.0–5.0); sutural ridge width, about 1. The tail and body of the spores differed in colour when stained with each of three dyes. They are, therefore, composed of different material.     

Morphology,seasonality and phylogeny of Zschokkella soleae sp. n. (Myxozoa,Myxosporea) parasite of Solea solea (L.) (Pleuronectiformes,Soleidae) from Ghar El Melh Lagoon,Tunisia

A new Myxosporea, Zschokkella soleae sp. n., was found in the gall bladder and the bile of common sole, Solea solea (L.), from Ghar El Melh Lagoon in north‐east Tunisia. This is the first record for the presence of Zschokkella species in Tunisian waters. The parasite's plasmodia are polysporic with variable size and shape. Some plasmodia appeared attached to the gall bladder epithelium while others were found free in bile. Mature spores are ellipsoidal in frontal view 13.8 ± 0.38 μm long and 10.86 ± 0.40 μm wide with two equal size spherical polar capsules 3.6 ± 0.43 μm in size. The prevalence of infection seems to correlate with host size and changes over the year with maximum percentage in summer. Based on the 18S rDNA sequence data, Z. soleae sp. n. is readily distinguishable from other myxozoan DNA sequences in GenBank. Phylogenetically, the new species is placed in the freshwater Myxidium clade including several Zschokkella spp. infecting the gall bladder. Morphology, histology as well as DNA sequence analysis indicate that the examined species differs from all previously described Zschokkella species.     

引起池养异育银鲫高死亡率的粘孢子虫新种咽碘泡虫形态和分子分析

对近几年发生在江苏省盐城地区引起池养异育银鲫大批死亡的粘孢子虫进行了形态和分子等方面分析研究,发现该粘孢子虫主要特点是:孢子梨形,部分孢子后部外周包围有透明无色的膜状鞘和壳瓣底部内侧呈现1～6个"V"形缺刻,两个极囊大小不等,孢子前端内侧两个极囊间有一个细长的囊间突起,胚质中无嗜碘泡,孢囊大小10～25 mm,孢子长16.82±0.43(16.03～17.69)μm,孢子宽10.26±0.43(9.12～10.88)μm,孢子厚8.09±0.29(7.50～8.75)μm,孢子长宽比1.64±0.09(1.50～1.93);大极囊长8.66±0.25(8.25～9.16)μm、宽3.65±0.25(3.01～4.19)μm,小极囊长8.35±0.28(7.60～8.85)μm、宽3.58±0.23(3.09～4.11)μm,囊间突起长1.80±0.12(1.59～2.00)μm。特异性地寄生在异育银鲫的口咽腔上颚的咽组织内、具有寄主和寄生在咽部的专一性,PCR扩增得到1 576 bp的18S rDNA序列,GenBank登录号为JQ726700。该粘孢子虫与相近的其它粘孢子虫比较,孢子长分别与白鲟碘泡虫(Myxobolus psephurusi)和扭曲碘泡虫(M.twistus)无显著差异(P>0.05),与M.ampullicapsulatus、M.wulii和鳙碘泡虫(M.aristichthydis)分别有显著差异(P<0.05);孢子宽和厚、极囊长和宽分别与M.ampullicapsulatus、M.wulii、白鲟碘孢虫(M.psephurusi)、鳙碘泡虫(M.twistus)和扭曲碘孢虫(M.aristichthydis)有显著差异(P<0.05);分子系统树分析结果显示,与M.ampullicapsulatus在同一个分支中,亲缘关系最近。从孢子形态学、寄主的特异性、寄生部位的专一性以及18SrDNA序列等特点综合比较分析,表明该粘孢子虫为一新种,命名为咽碘泡虫Myxobolus pharynae n.sp.。     

荆州碘泡虫(粘体动物门,碘泡虫科)重描述及其基于18S rDNA系统发育关系分析

本实验利用现行主流分类衍征,重新对荆州碘泡虫(Myxobolus kinchowensis)进行了详细描述,其分类特征如下:包囊圆形,寄生于鲫肌肉与肾脏,肌肉包囊大小(126.7±1.8)μm,肾脏包囊直径为94.2μm;两寄生部位各形态参数无显著差异,成熟孢子正面观呈梨形,缝面观呈纺锤形,含一大一小两梨形极囊;无明显囊间突起,孢子后端无褶皱,无粘液膜。组织病理显示在两寄生部位均未引起严重的炎性反应,且感染强度不高,推测该种对宿主无显著影响。基于18S r DNA进化分析发现荆州碘泡虫与寄生在肌肉部位的碘泡虫属种类聚为一个大枝,然后该大枝又根据地理位置远近分为北美枝、欧洲枝以及亚洲枝。通过形态比较研究以及分子分析可确定荆州碘泡虫为有效种,其寄主为鲫,寄生部位为肌纤维间和肾小囊。此外,两组织差异明显的寄生部位出现说明荆州碘泡虫相应的放射孢子虫在宿主鲫体内存在不同的发育与移行途径,而肌肉可能为其常规寄生部位,肾脏为其异常寄生部位,这种寄生部位的转移与宿主转变可能是粘孢子虫物种多样性形成的机制。     

Renal myxozoanosis in weedy sea dragons, Phyllopteryx taeniolatus (Lacepède), caused by Sinuolinea phyllopteryxa n. sp.

Renal myxozoanosis was diagnosed histologically in 11 captive, wild caught, adult weedy (common) sea dragons, Phyllopteryx taeniolatus, from three separate public aquaria in the United States. Myxozoan spores were visible in wet mounts of kidney tissue and were associated with renal tubular dilatation and tubular epithelial cell hypertrophy. Light and electron microscopy revealed spore morphology consistent with the genus Sinuolinea. Spores were spheroidal, slightly dorso-ventrally compressed, length (L) 17.1 x width (W) 16.4 x thickness (T) 15.6 microm, with two shell valves joined at a distinct, sinuous sutural ridge, and had two nearly spherical polar capsules, L 5.5 x W 5.0 microm, with five to seven turns of the polar filament. There were no extra-valvular ridges or protrusions. DNA sequencing required the design of three new primers that yielded 1740 bp of 18S ribosomal DNA sequence. The parasite was determined to be novel based on morphological and molecular data, and was given the name Sinuolinea phyllopteryxa after its vertebrate host.     

Thelohanellus testudineus n. sp. (Myxosporea: Bivalvulida) infecting the skin of allogynogenetic gibel carp Carassius auratus gibelio (Bloch) in China

A Thelohanellus species was encountered during a survey on Thelohanellus diversity of Carassius auratus gibelio (Bloch) in China. The infection is characterized by the presence of large cysts of 1.4–3.2 cm in diameter in the skin of host. Mature spores were ampullaceous in frontal view and testudinate in lateral view, measuring 19.7 ± 0.7 (18.6–20.8) μm long, 7.6 ± 0.4 (6.6–8.4) μm wide and 7.3 ± 0.5 (6.6–8.8) μm thick. The single polar capsule was elongated pyriform, with 11.1 ± 0.5 (10.0–11.9) μm long and 5.3 ± 0.3 (4.3–5.8) μm wide. Polar filaments coiled with 7–8 turns. Scanning electron microscopy revealed a smooth spore surface with flat side and convex side. The sutural line was straight or ‘S’ like, running near the middle of the valves. Histologically, the large cysts consisting of numerous small plasmodia developed in the dermis of the skin. The BLAST search indicated that the newly obtained ssrRNA gene sequences did not match any available sequences in GenBank and phylogenetic analysis placed it in the Thelohanellus clade. Based on morphology and molecular differences with reported Thelohanellus spp., this parasite was described as a new species of genus Thelohanellus.     

Life cycle inference and phylogeny of Ortholinea labracis n. sp. (Myxosporea: Ortholineidae), a parasite of the European seabass Dicentrarchus labrax (Teleostei: Moronidae), in a Portuguese fish farm

Ortholinea labracis n. sp. is described and its life cycle is inferred from a Southern Portuguese fish farm, with basis on microscopic and molecular procedures. This myxosporean parasite infects the urinary bladder of the European seabass Dicentrarchus labrax and the intestinal epithelium of a marine oligochaete of the genus Tectidrilus. Myxospores subspherical in valvular view and ellipsoidal in sutural view measuring 7.6 ± 0.3 (6.8–8.7) μm in length, 7.2 ± 0.2 (6.7–7.7) μm in width and 6.5 ± 0.4 (5.8–7.7) μm in thickness. Two polar capsules, 3.0 ± 0.2 (2.6–3.4) μm long and 2.4 ± 0.1 (2.0–2.9) μm wide, located at the same level, but with divergent orientation and opening to opposite sides of the suture line. Sequencing of the SSU rRNA gene revealed a similarity of 100% between the analysed myxospores and triactinomyxon actinospores. The phylogenetic setting of O. labracis n. sp. shows subgrouping in correlation with tissue tropism, but identifies this parasite as another exception to the main division of Myxosporea into the main freshwater and marine lineages.     

Microsporidium rhabdophilia n. sp. from rodlet cells of salmonid fishes

Abstract. A microsporidian parasite, Microsporidium rhabdophilia n. sp. is described from rodlet cells of salmonid fishes. Chinook salmon, Oncorhynchus tshawytscha , coho salmon, Oncorhynchus kisutch , steelhead rainbow trout, Salmo gairdnerii gairdnerii , and various strains of domesticated rainbow trout were found infected. In living wet mount phase-contrast observations of various tissues, 16 mature spores could be seen infecting the nucleus of rodlet cells. The number of spores infecting each nucleus generally numbered 16 and spores were not found in any cell or organelle other than the nucleus of the rodlet cell. All observations were limited to California hatchery-reared fish.     

Further studies on Zschokkella russelli Tripathi (Myxozoa: Myxosporea) from Ciliata mustela L. (Teleostei; Gadidae), with emphasis on ultrastructural pathology and sporogenesis

Abstract In this second study of the myxozoan Zschokkella russelli Tripathi from Wales, infection occurred in 71-0% of five-bearded rocklings, Ciliata mustela L.; all infected fish were mature and immature fish were uninfected. Histologieal studies showed ehanges to gallbladder and liver that mostly conformed with earher findings, but sinusoidal dilation, which had not been seen previously, was present in three of 22 infected livers. Thickening around hepatic ducts was shown by transmission electron microscopy (TEM) to comprise fibroblasts and associated collagen bundles, while the attenuated epithelium of hepatic ducts bore few mierovilli. Zschokkella russelli plasmodia were seen by TEM to have fine tubular structures, particularly adjacent to developing sporonts. Spores showed long extensions to the sporoplasm, while spore valves had up to 18 surface ridges each and depressions between ridges were supported by microtubules. Otherwise, in its general ultrastructure and sporogenesis Z. russelli resembled other myxosporida.     

Henneguya pagri n. sp. (Myxozoa: Myxosporea) causing cardiac henneguyosis in red sea bream, Pagrus major (Temminck & Schlegel)

Henneguya pagri n. sp. (Myxozoa: Myxosporea) is described from netpen-cultured red sea bream, Pagrus major, in Japan. Affected fish displayed anaemic gills, an enlarged bulbus arteriosus and internal haemorrhaging in the pericardial cavity. Disease outbreaks occurred during the summer and the prevalence of infection reached 75% in August. Plasmodia of H. pagri developed in the bulbus arteriosus of red sea bream, in which degenerative cardiomyopathy was observed. Following maturation of the parasite, the influx of spores into the gills caused congestion of the gill capillaries, resulting in proliferative branchitis. Spores (10.5 x 7.5 microm) were ovoid with two caudal appendages (29.6 microm in average length), with a whip-like extension from the end. Partial small subunit ribosomal RNA gene sequences of H. pagri are closely related to those of H. lateolabracis infecting the bulbus arteriosus of Chinese sea bass, Lateolabrax sp.     

Myxobolus erythrophthalmi sp. n. and Myxobolus shaharomae sp. n. (Myxozoa: Myxobolidae) from the internal organs of rudd, Scardinius erythrophthalmus (L.), and bleak, Alburnus alburnus (L.)

During a survey of myxosporean parasites of cyprinid fish in Hungary, infections caused by unknown Myxobolus spp. were found in the internal organs of rudd, Scardinius erythrophthalmus, and bleak, Alburnus alburnus . Small plasmodia developed in blood vessels of the kidney, liver, testes and intestinal wall. The parasites were studied on the basis of spore morphology and by histological and molecular methods. In most cases, plasmodia were surrounded by host tissue without a host reaction; however, in advanced cases, a connective tissue capsule was seen around plasmodia. Spores collected from the two fish species differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. The two species, described as M. erythrophthalmi sp. n. from rudd and M. shaharomae sp. n. from bleak, are characterized by a specific histotropism to blood vessels, while the organ specificity involves the kidney and for the latter species, most internal organs.     

A new myxosporidan, Dicauda atherinodi n.g., n. sp. of the minnow, Notropis atherinoides Rafinesque

Abstract. Dicauda atherinoidi n.g., n. sp. (Protozoa: Myxosporida) was found in feral minnows, Notropis atherinoides (Cyprinidae), from western Lake Erie (Sterling State Park), Michigan, and the lower Mohawk and Hudson Rivers, New York. Dicauda , closely related to Myxobolus , differs from it in having two, occasionally three or more, rigid tail-like possibly mucoid appendages attached to the sutural ridge. The cysts are subdermal and most abundant on the head. Histological damage is not striking.     

Ultrastructural observations of the life cycle stages of Ameson atlanticum sp. nov., a microsporidan parasitizing Cancer pagurus L.

Abstract. Cancer pagurus (Cancridae) from the Atlantic coast of France is parasitized by a new species of microsporida Ameson atlanticum sp. nov. The main stages of the life cycle of the parasite are a monokaryotic and then diplokaryotic meront, tetranucleate (at least) sporont fsporogonial sporont), uninucleate sporoblast and spore. The spore (1.9 × 1.5 μm) possesses 11–12 coils of the polar filament and a lamellar polaroplast. Hairlike appendages are present on the surface of the sporoblastic plasmodium, sporoblast and spore. All stages take place in direct contact with the muscular tissue of the crab. Infection provokes the destruction of 80% of host muscle myofibrils.     

Henneguya pseudorhinogobii n. sp. (Myxozoa: Myxosporea) parasitizing the gills of the freshwater goby Rhinogobius sp. OR from the Nagara River and redescription of Henneguyarhinogobii

Two types of infection with myxosporean parasites, which were different in cyst size, were found from the gill of Rhinogobius sp. OR collected from the Nagara River, Gifu Prefecture, Japan. A myxosporean forming large-type cysts in the gill filament was morphologically identified as Henneguya rhinogobii. Another myxosporean forming small-type cysts was found to be parasitic in the gill lamella. Average spore sizes of the latter myxosporean were 15.8 (range 14.2–17.8) μm in length, 5.3 (4.7–5.8) μm in width, 6.5 (5.9–7.6) μm in polar capsule length and 34.9 (25.3–42.9) μm in caudal appendage length, which were almost identical to those of H. rhinogobii. However, the two were distinguishable by the location in the gill (intrafilamental or intralamellar) and by the difference in the sequence of SSU rDNA (about 96% similarity). We propose the myxosporean forming intralamellar small-type cysts as Henneguya pseudorhinogobii n. sp. and redescribe H. rhinogobii by morphological and molecular studies.     

Kudoa trifolia sp. n. - molecular phylogeny suggests a new spore morphology and unusual tissue location for a well-known genus

A new species of myxozoan, Kudoa trifolia sp. n., was found in various organs of the golden grey mullet, Liza aurata (Risso), and the thinlip mullet, L. ramada (Risso), from the western Mediterranean. Spores developed in subspherical plasmodia of 0.28-1 mm diameter within connective tissue, predominantly in the spleen, the outer wall of the gall bladder and the gut, the mesenteries and occasionally also in the gills. The spores of K. trifolia differ from the commonly known shape of Kudoa by considerable enlargement of one of the four valve cells, thus forming a 'spore body', which contains the major part of the binucleate sporoplasm. Scanning electron microscopy of the spores revealed the presence of grape-like appendages, which occur in bundles terminally on the valve cells. Phylogenetic analysis based on the 18S rDNA sequence of K. trifolia showed that this species is deeply embedded in the genus Kudoa despite its aberrant morphology and host tissue location. This suggests important amendments to the morphological diagnosis of the genus Kudoa.     

Myxobolus neurophilus Guilford 1963 (Myxosporea: Myxobolidae): a common parasite infecting yellow perch Perca flavescens (Mitchell, 1814) in Saskatchewan,Canada

The goal of this study was to identify a myxosporidian parasite infecting the central nervous system of yellow perch Perca flavescens (Mitchell, 1814) observed while investigating a fish kill in Saskatchewan, Canada. Fish were collected from seven different lakes, from two distinct watersheds. Sixty-four per cent (54/86) of yellow perch contained myxozoan pseudocysts located throughout the spinal cord and brain. Myxospores measured 16.5 μm (range 16.2–16.8) long and 8.2 μm (range 7.9–8.4) wide and contained two pyriform, mildly dissymmetrical, polar capsules measuring 7.7 μm (range 7.3–8.1) long and 2.7 μm (range 2.4–3.0) wide. The polar capsules each contained a single polar filament, with 7–9 turns per polar filament coil. Sequencing of the 18S SSU rDNA gene demonstrated >99% similarity to Myxobolus neurophilus. In 60% of infected fish, there was a mild to moderate, non-suppurative myelitis or encephalitis, or both, associated with myxospores. Axonal degeneration was present in rare cases. These findings extend the geographical distribution of M. neurophilus and suggest it may be widespread in yellow perch populations in Saskatchewan.     

Cell and tissue reactions of turbot Scophthalmus maximus (L.) to Tetramicra brevifilum gen. n., sp. n. (Microspora)

Abstract. Tetramicra brevifilum gen, n. sp, n. is described from the connective tissues throughout the body musculature of turbot Scophthalmus maximus (L.). Uninucleate spores (4.8·2 μm) are characterized by a large posterior vacuole, electron dense inclusion bodies in cytoplasm and nucleus and short filaments with 3–5 coils (50 μm extruded). Sporogony is apansporoblastic and tetrasporoblastic, within a host vacuole. Features of the xenoma (2 mm diameter) include a microvillous surface layer with microtubules and microfilaments and a reticulate nucleus with numerous nucleoli. Adherence between adjacent xenomas results in composite cysts of various sizes and shapes depending on site, being dendritic in the myomeres, arms extending between the fibres. Effects on the host, other than eventual destruction of the host cell, include displacement of muscle fibres in myomeres with loss of attachment to myocommata. Breakdown of the xenoma with release of spores into the connective tissue matrix was associated with a localized necrosis affecting surrounding muscle fibres, with leucocyte infiltration and collagen deposition. Spores phagocytosed by macrophages were destroyed in vacuoles, some with multi-laminate walls. Experimental infections established by intramuscular injection at marked sites remained localized, which suggested that xenomas afford sufficient scope for spore production without the need of secondary invasion. The swimming efficiency of turbot would be impaired in severe infections leading to lowered growth rates and increased mortality in wild populations due to predation and starvation. Feeding hierarchies exist in turbot and the disease could prove significant in farming conditions.     

Description of Myxobolus bulbocordis sp. nov. (Myxosporea: Myxobolidae) from the heart of Barbus sharpeyi(Günther) and histopathological changes produced by the parasite

A new myxosporean, Myxobolus bulbocordis sp. nov., has been found in the heart of a Mesopotamian fish, Barbus sharpeyi (Günther), in rivers in Southwest Iran. Cysts containing matured spores were located on the serosa of the atrium cordis, bulbus arteriosus, larger gill arteries and inside the wall of the bulbus. The species showed an affinity to connective tissue cells and was never associated with the muscles. Mature cysts were surrounded by a connective tissue capsule composed of two to three layers. Spores in disrupted cysts were infiltrated by epithelioid cells and macrophages. The spores found in Barbus sharpeyi differed in size and morphology from species known from other barbels.     

<Emphasis Type="Italic">Myxobolus nagaraensis</Emphasis> n. sp. (Myxozoa: Myxosporea) causes abdominal distension of freshwater goby <Emphasis Type="Italic">Rhinogobius</Emphasis> sp. OR type from the Nagara River

ABSTRACT:   A new myxosporean parasite was found in the body cavity and caudal peduncle of the freshwater goby Rhinogobius sp. Orange type (OR) collected from the Nagara River, Gifu Prefecture, Japan. Infected fish exhibited substantial swelling of the abdomen caused by large parasitic cysts approximately 10 mm in size, formed in the visceral cavity. The cyst was a compacted aggregate of several smaller cysts, similar to a bunch of grapes in appearance. Histological examination showed that plasmodia developed within the renal capsule, and finally occupied the visceral cavity. Spores were ovoid with an attenuated anterior end. Sutural ridges were conspicuous with several folds on the edge. Average spore size was 11.9 (10.5–13.5) μm long, 9.0 (8.0–10.0) μm wide, and 6.5 (6.0–7.0) μm thick. Two equal polar capsules were 5.5 (4.5–6 0) μm long and 3.0 (2.5–4.0) μm wide. Partial small subunit ribosomal DNA sequences of the myxosporean were distinct from those of other myxozoan species in GENBANK. A new species name, Myxobolus nagaraensis , is proposed for this parasite.