Henneguya lesteri n. sp. (Myxosporea) is described from sand whiting, Sillago analis, from the southern Queensland coast of Australia. H. lesteri displays a preference for the pseudobranchs and is typically positioned along the afferent blood vessels, displacing the adjoining lamellae and disrupting their normal array. The plasmodia appeared as whitish-hyaline, elliptical cysts (mean dimensions 230 × 410 µm) attached to the oral mucosa lining of the hyoid arch on the inner surface of the operculum. Infections of the gills were also found, in which the plasmodia were spherical, averaged 240 × 240 µm in size and were located on the inner hemibranch margin. The parasites lodged in the gill filament crypts and generated a mild hyperplastic response of the branchial epithelium. In histological sections, the plasmodium wall and adjoining ectoplasm appeared as a finely granulated, weakly eosinophilic layer. Ultrastructurally, this section of the host-parasite interface contained an intricate complex of pinocytotic channels. H. lesteri is polysporic, disporoblastic and pansporoblast forming. Sporogenesis is asynchronous, with the earliest developmental stages aligned predominantly along the plasmodium periphery, and maturing sporoblasts and spores toward the center. Ultrastructural details of sporoblast and spore development are in agreement with previously described myxosporeans. The mature spore is drop-shaped, length (mean) 9.1 µm, width 4.7 µm, thickness 2.5 µm, and comprises 2 polar capsules positioned closely together, a binucleated sporoplasm and a caudal process of 12.6 µm. The polar capsules are elongated, 3.2 × 1.6 µm, with 4 turns of the polar filament. Mean length of the everted filament is 23.2 µm. Few studies have analyzed the 18S gene of marine Myxosporea. In fact, H. lesteri is the first marine species of Henneguya to be characterized at the molecular level: we determined 1966 bp of the small-subunit (18S) rDNA. The results indicated that differences between this and the hitherto studied freshwater Henneguya species are greater than differences among the freshwater Henneguya species.KEY WORDS: Marine Myxosporea · Pseudobranchs · Gills · Ultrastructure · 18S rDNA gene sequence Resale or republication not permitted without written consent of the publisherDis Aquat Org 46: 197-212, 2001 corded Henneguya spp. from Australia are 4 unidentified species from freshwater fish (O'Donoghue & Adlard 2000) and 2 from coastal marine fish: Henneguya spp. from yellowfin bream Acanthopagrus australis (Gunther 1859) in Queensland (Roubal 1994) and grey mullet Mugil cephalus Linnaeus 1758 in New South Wales (Lom et al. 1992).The present study describes a new species, Henneguya lesteri n. sp., from the pseudobranch and gills of sand whiting Sillago analis from a mangrove mud flat and a sandy beach at Moreton Bay, Queensland, Australia. MATERIALS AND METHODS Collection of material. Twenty-three sand whitingSillago analis Whitley 1943 were collected from 2 coastal sites of Moreton Bay during 2 sampling periods in...

Myxidiurn leei n. sp. is described from cultured sea bream Sparus aurata L. in Cyprus and Israel. It is histozoic in the intestinal wall and forms small plasmodia that give rise to 2 spores each. The average size of fixed spores is 14.7 pm in length and 6.9 pm in width; their shape is arcuate, elongated polar capsules (average size 3.2 X 7.4 pm, with 7 turns of the polar filament) open at one side of the spore. The case of t h~s species, which reveals a combination of taxonomic characters fitting both Myxidium and Zschokkella, stresses once again the non-existence of a sharp morphological boundary between the 2 genera.

No abstract

An integrated biological effect monitoring concept has been tested in flounder (Platichthys flesus L.) from four locations with different anthropogenic impact in the German Bight. During 3 years of sampling, biomarkers at all levels of biological organisation from the molecular to the ecosystem level were applied and tested on 742 individual fish of body lengths between 18 and 25 cm. At the ecosystem level, the fish were taken as a habitat for the parasite assemblage. The hypothesis was that changes in the environment might lead to changes in the species diversity of parasites and in the infection intensity of single species, as well as between heteroxenic and monoxenic parasite species (H/M ratio). At the molecular level, activity of the CYP1A-dependent monooxygenase ethoxyresorufin O-deethylase (EROD) was used as a biomarker of exposure. At the subcellular level, the integrity of lysosomal membranes in hepatocytes was taken as an indicator of non-specific acute and chronic toxic effects. Both biomarkers are recommended by the ICES Advisory Committee on the Marine Environment for the application in biological effects monitoring programmes. In addition, neutral lipid content in the liver was used as a marker for pathologically induced fat accumulation. In the same individual fish, a new method for the measurement of macrophage aggregate activity in the liver was tested for its application and reliability in reflecting immunosuppression. Tests were accompanied by chemical analysis of standard organochlorine and heavy metal residues in flounder tissue. A total of 33 parasite species were found. As an indicator species, the mean abundance of Trichodina sp. reflected best the pollution gradient observed with highest infection intensity at the most polluted location. Species diversity was significantly higher in fish caught near the reference site and significantly lower in fish from the polluted Elbe estuary. The use of the heteroxenous/monoxenous species ratio as a marker was not useful at the locations investigated because of the dominance of heteroxenous species at all habitats. Since EROD activity and macrophage aggregate activity were dependent on sex and maturity of female flounder, only male fish were taken into consideration for the integrated evaluation of data. All biochemical and histochemical tests were able to reflect accurately the site-specific differences, as well as an observed pollution event at the end of 1995 as determined by chemical analyses. The correlation analysis revealed a connection not only between the single parasitological and biochemical parameters but also within these groups. The non-specific immune response and Trichodina infection intensity were correlated with all other parameters, leading to the assumption that these may serve as links between the lowest and the highest levels of biological organisation. The simultaneous use of metabolic and parasitological results facilitated the interpretation of the observed variations of the data and the distinction between natural ...

Gilt-head sea bream, Sparus aurata L., the Mediterranean's most important mariculture species, has been cultured for the last 30 yr in Eilat (Israeli Red Sea). Kudoa sp. was the first myxosporean parasite reported from this species. In recent years, an increase in prevalence in both land-based and sea-cage facilities in Eilat has been observed. Infections with the same Kudoa species appeared in cultured European sea bass Dicentrarchus labrax (L.) and grey mullet Mugil cephalus in the same farms, as well as in 10 species of wild Red Sea reef fish, indicating that Kudoa sp. is not fastidious with regard to its host. All affected species displayed 1- to 2-mm (up to 5 mm) whitish, spherical, or oval polysporous plasmodia. The parasite established multiple site infections, most commonly in the muscles and intracranial adipose tissue of the brain and eye periphery. Other sites were subcutaneous adipose tissue, nerve axons, mouth, eye, mesenteries, peritoneum, swim bladder, intestinal musculature, heart, pericardium, kidney, and ovary. On the basis of spore morphology, the parasite was identified as Kudoa iwatai Egusa and Shiomitsu, 1983. Ultrastructural features were comparable to those of previously studied Kudoa species. The 18S rDNA from 7 Red Sea isolates was sequenced and compared with the sequence of the same gene from K. iwatai isolated from cultured red sea bream, Pagrus major, in Japan. The phylogenetic position of K. iwatai within the genus was determined using sequence analysis of all related taxa available in GenBank. The 3 isolates of K. iwatai clustered together on a newly formed, highly supported clade. The Red Sea strain of K. iwatai is apparently native to the region. In the absence of records of this Kudoa sp. from the extensive Mediterranean sea bream and sea bass production industries, introduction with its Mediterranean hosts seems unlikely. Therefore, we conclude that K. iwatai is an Indo-Pacific species that, in the Red Sea, has extended its host range to include the allochthonous gilt-head sea bream, European sea bass, and grey mullet.