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The acanthocephalan fauna of Australian freshwater fishes was documented from field surveys, a literature survey and examination of specimens registered in Australian museums. From the 4030 fishes, representing 78 of the 354 Australian freshwater fish species (22%), examined for infection seven species of acanthocephalan were recovered. These species comprised five endemic species, three in endemic genera, two species in cosmopolitan genera, one species not fully identified and 1 putative exotic species recovered from eight species of fish. Of these Edmonsacanthus blairi from Melanotaenia splendida, was the only acanthocephalan found at a relatively high prevalence of 38·6%. These findings are indicative of a highly endemic and possibly depauperate acanthocephalan fauna. Species richness was higher in the tropical regions than the temperate regions of the country. Exotic acanthocephalan species have either not been introduced with their exotic hosts or have been unable to establish their life cycles in Australian conditions. Consequently, acanthocephalans have not yet invaded endemic Australian fish hosts.

Diseases of aquatic animals have had, and continue to have, a significant impact on aquatic animal health. In Australia, where fisheries and aquaculture are important industries, aquatic species have been subject to serious disease outbreaks, including pilchard herpesvirus, the cause of one of the largest wild fish kills ever recorded. At the same time, there is a consensus that Australia's parasite fauna are largely unknown, and that aquatic animal health information is difficult to access. Managing aquatic animal diseases is challenging because they may be entirely new, their hosts may be new to aquaculture, and specialist expertise and basic diagnostic tools may be lacking or absent. The Neptune project was created in response to these challenges, and it aims to increase awareness of aquatic animal diseases, improve disease management, and promote communication between aquatic animal health professionals in Australia. The project consists of an online database, a digital microscopy platform containing a whole-slide image library, a community space, and online communications technology. The database contains aquatic animal health information from published papers, government reports, and other sources, while the library contains slides of key diseases both endemic and exotic to Australia. These assets make Neptune a powerful resource for researchers, students, and biosecurity officials.

During a parasitological survey, Myxidium-like spores were identified in the gall bladders of marine fishes from Australian waters. This paper describes four novel species of Ellipsomyxa Køie, 2003, three novel species of Myxidium Bütschli, 1882 and six novel species of Zschokkella Auerbach, 1910 from teleosts from Australian waters using a combination of morphological, biological and molecular characters. Phylogenetic analyses showed a monophyletic relationship of all Ellipsomyxa spp. sequences with Sigmomyxa sphaerica (Thélohan, 1895) and Myxidium queenslandicus Gunter & Adlard, 2008 as sister species to the clade. The validity of genus Sigmomyxa Karlsbakk & Køie, 2012 is discussed. In phylogenetic analyses, the novel species of Myxidium fell within the 'marine' clade of Fiala (2006). However, the novel species of Zschokkella fell within the 'freshwater' clade of Fiala (2006) and formed a distinct clade with all other sequences of Zschokkella spp. from the gall bladder of marine fish and a sequence of a species of Myxobolus Bütschli 1882, also from the gall bladder of a marine fish. This is the second distinct marine lineage to emerge within the freshwater clade.

Ceratomyxa parasites from the gall bladders of 23 species of cardinalfishes (family Apogonidae) from Australian waters were examined for their taxonomic identity and phylogenetic relatedness. We identified 15 of the 23 apogonid fish species infected with species of Ceratomyxa. Although the majority of apogonid species harboured only a single Ceratomyxa species, four were found with multiple species of Ceratomyxa. This study describes eight novel species using a combination of morphological, small subunit ribosomal DNA (SSU rDNA) and biological characters. Six Ceratomyxa species are reported from single apogonid species, while two are reported from multiple host species. Molecular data were critical in identifying several morphologically cryptic species. However, our results suggest that SSU rDNA was not capable of distinguishing all the species present in the current study system and alternative genetic markers should be investigated in the future.

Kudoa spp. from the musculature and intestinal mucosa of species of the teleost family Apogonidae were examined for their taxonomic identity. Two novel species are characterised: Kudoa cheilodipteri n. sp. from the musculature of Cheilodipterus quinquelineatus Cuvier, Ostorhinchus cyanosoma (Bleeker) and O. aureus (Lacépède); and Kudoa cookii n. sp. from the submucosa of the intestines of O. cookii (Macleay) only. Both species are characterised using morphology, small subunit ribosomal DNA (SSU rDNA), large subunit ribosomal DNA (LSU rDNA), and biological characters. Three new host records, O. cyanosoma, O. aureus and Apogon doederleini, and associated geographical, morphological and genetic data are also provided for Kudoa whippsi Burger & Adlard, 2010. Morphological and molecular intra-specific variation of all isolates assigned to K. whippsi is also examined. Phylogenetic analyses further support the idea that tissue tropism is a distinguishing character between morphologically similar species; species reported here display close relatedness to morphologically similar species infecting the same tissue within their hosts.

Six novel species of Chloromyxum Mingazzini, 1890 are described using a whole evidence approach combining morphometric and molecular data, together with features of their biology. Elasmobranchs were collected in Australian waters, from the Great Barrier Reef, Queensland, off Lizard and Heron Islands; from Moreton Bay, southeast Queensland; off Hobart, Tasmania; and from the Tamar River, Launceston, Tasmania. The novel species proposed here are: Chloromyxum hemiscyllii n.sp. from Hemiscyllium ocellatum; Chloromyxum kuhlii n.sp. from Neotrygon kuhlii; Chloromyxum lesteri n.sp. from Cephaloscyllium laticeps; Chloromyxum mingazzinii n.sp. from Pristiophorus nudipinnis; Chloromyxum myliobati n.sp. from Myliobatis australis; and Chloromyxum squali n.sp. from Squalus acanthias. A seventh species from Squalus acanthias is also reported but due to limited material is not formally described. Molecular phylogenetic analyses revealed that the genus Chloromyxum is polyphyletic, and species from elasmobranchs form a well-supported sister clade, with the type species Chloromyxum leydigi, to all other congeneric species clustering within the freshwater myxosporean clade. Morphological analysis showed that elasmobranch-infecting species are predominantly pyriform shaped, have clearly thickened spore apex and possess caudal filaments, compared to other Chloromyxum species which are generally spherical or subspherical, and lack caudal filaments. These morphological and phylogenetic data provide further support for the erection of new genera, but we conservatively consider the species described in this study and other elasmobranch-infecting Chloromyxum species as Chloromyxum sensu strictu, whilst the freshwater teleost infecting and amphibian infecting species we will assign as Chloromyxum sensu lato, until more comprehensive data are available., (Crown Copyright © 2011. Published by Elsevier Ireland Ltd. All rights reserved.)

Five novel species, Auerbachia scomberoidi n. sp., Auerbachia chaetodoni n. sp., Auerbachia caranxi n. sp., Coccomyxa colurodontidis n. sp. and Coccomyxa gobiodoni n. sp. are described from the gall bladders of marine teleosts. These species descriptions provide the first record of Auerbachia from Australian waters. Each species is characterized morphologically, including additional measurements for Auerbachia spp. and small subunit ribosomal DNA (SSU rDNA) sequences were determined for molecular phylogenetic analyses. All 5 species were each recovered from a single (and different) species of host. Phylogenetic analyses revealed a close genetic relatedness between members of Auerbachia and Coccomyxa. Based on these phylogenetic data, on obvious paraphyly displayed by the Myxidiidae and on priority, we propose the re-establishment of the family Coccomyxidae to house all species of the genera, Coccomyxa, Auerbachia and Globospora.

Kudoid parasites are significant pathogens of marine fish. In the past, specific identification has been difficult due to a paucity of detailed morphological and biological information provided in the original description of some species. However, the introduction of DNA analysis has dramatically improved diagnosis. For morphological characterization, this paper proposes a new set of schematics including additional measurements to give a more thorough description of spore morphology, and provides evidence for uniqueness of 4 new species: Kudoa gunterae n. sp. (from 10 pomacentrid species and 1 apogonid species), K. kenti n. sp. (from 4 pomacentrid species), K. paraquadricornis n. sp. (from 4 carangid species), and K. whippsi n. sp. (from 8 pomacentrid species and 1 apogonid species). Subtle morphological differences found between closely related species were reflected in their genetics, with increased resolution provided by the large subunit, compared with that of the small subunit, of the ribosomal DNA gene region. This article proposes comprehensive requirements for species descriptions within the Kudoidae that incorporate biology, morphology, and genetic sequence.

Four new species of Ceratomyxa Thélohan, 1892 are described from the gall bladders of fishes collected off Lizard Island, Australia. These species are characterised using a combination of morphometric and molecular data. Ceratomyxa bartholomewae sp. n. is described from Hyporhamphus dussumieri (Valenciennes) (family Hemirhamphidae); C. koieae sp. n. is described from Sphyraena forsteri Cuvier (family Sphyraenidae); C. pantherini sp. n. is described from Bothus pantherinus (Rüppell) (family Bothidae) and C. reidi sp. n. is described from Chaetodon vagabundus Linnaeus (family Chaetodontidae). A fifth species from Zebrasoma veliferum (Bloch) (family Acanthuridae) is also reported but due to limited material is not formally described here.

Ceratomyxa spp. from the gall-bladder of five members of the family Serranidae were examined for their taxonomic identity. This paper describes seven new ceratomyxid species, i.e. C. brayi n. sp. and C. whippsi n. sp from Cephalopholis boenak (Bloch); C. cutmorei n. sp. from Epinephelus fasciatus (Forsskål); C. gleesoni n. sp. from Plectropomus leopardus (Lacépède); C. hooperi n. sp. and C. nolani n. sp. from E. quoyanus (Valenciennes); and C. yokoyamai n. sp. from E. maculatus (Bloch). Each species is characterised morphologically and small subunit (SSU) rDNA sequences. All seven new species have so far been found in only a single host species.

Parasites of the genus Kudoa (Phylum Myxozoa) have long been known to cause considerable losses to finfish aquaculture. One such parasite species, Kudoa amamiensis, causes unsightly white cysts in the skeletal muscle of yellowtail kingfish, Seriola quinqueradiata, in Japan rendering the fillets unmarketable. The authors who characterized K. amamiensis, Egusa & Nakajima, 1980, hypothesized that yellowtail kingfish, as non-natives to the area, were accidental hosts of the parasite and that it normally infects native reef fish (damselfish, Family Pomacentridae). Since then, we have found parasites that are consistent with the description of K. amamiensis in two species of damselfish and one species of carangid fish in Australia, and it has been recorded previously in another species of reef-associated fish. Our morphometric, histological and DNA results suggest that these specimens are K. amamiensis, and are new host records for that species. Furthermore, our observations show that reef fish may act as a reservoir of myxozoan infection for commercial species, and as such should be considered an infection pathway for species in aquaculture.

Bivalvulidan parasites from the gall bladder of 31 species of damselfishes (family Pomacentridae) were examined for their taxonomic identity and their relatedness to other species of myxozoans. This paper describes 11 novel ceratomyxid species and a novel Myxidium sp. Each species is characterized morphologically and small subunit (SSU) rDNA sequences were used in molecular phylogenetic analyses. Five pomacentrid species were found to harbour multiple infections of bivalvulidan species. One species of Ceratomyxa and Myxidium were found to infect more than a single species of damselfish. Phylogenetic analyses revealed there has been no radiation of ceratomyxids that can be associated with the fish host taxon and that Myxidium queenslandicus n.sp. was more closely related to Zschokkella mugilis and Ellipsomyxa gobii than other members of the genus Myxidium.

A new species of the apicomplexan genus Leucocytozoon Berestneff, 1904, L. artamidis n. sp., is described from the Australian avian family Artamidae. Gametocytes and endogenous stages of the life-cycle are described together with early erythrocytic and leucocytic developing forms rarely described for species of this genus.

Marteilia sydneyi (Paramyxea) is the causative agent of QX disease in oysters. In spite of the economic impact of this disease, its origin and the precise reason(s) for its apparent spread in Australian waters are not yet known. Given such knowledge gaps, investigating the population genetic structure(s) of M. sydneyi populations could provide insights into the epidemiology and ecology of the parasite and could assist in its prevention and control. In this study, single strand conformation polymorphism (SSCP)-based analysis of a region (195 bp) of the first internal transcribed spacer (ITS-1) of ribosomal DNA was employed to investigate genetic variation within and among five populations of M. sydneyi from oysters from five different locations in eastern Australia. The analysis showed the existence of a genetic variant of M. sydneyi common to the Great Sandy Strait, and the Richmond and Georges Rivers, as distinct from variants at the Pimpama and Clarence Rivers. Together with historical and other information relating to the QX disease outbreaks in eastern Australia, the molecular findings support the proposal that the parasite originated in the Great Sandy Strait and/or Richmond River and then extended southward along the coast. From a technical perspective, the study demonstrated the usefulness of SSCP as a tool to study the population genetics and epidemiology of M. sydneyi.

Fish species around the world are parasitized by myxozoans of the genus Kudoa, several of which infect and cause damage of commercial importance. In particular, Kudoa thyrsites and Kudoa amamiensis infect certain cultured fish species causing damage to muscle tissue, making the fish unmarketable. Kudoa thyrsites has a broad host and geographic range infecting over 35 different fish species worldwide, while K. amamiensis has only been reported from a few species in Japanese waters. Through morphological and molecular analyses we have confirmed the presence of both of these parasites in eastern Australian waters. In addition, a novel Kudoa species was identified, having stellate spores, with one polar capsule larger than the other three. The SSU rDNA sequence of this parasite was 1.5% different from K. thyrsites and is an outlier from K. thyrsites representatives in a phylogenetic analysis. Furthermore, the spores of this parasite are distinctly smaller than those of K. thyrsites, and thus it is described as Kudoa minithyrsites n. sp. Although the potential effects of K. minithyrsites n. sp. on its fish hosts are unknown, both K. thyrsites and K. amamiensis are associated with flesh quality problems in some cultured species and may be potential threats to an expanding aquaculture industry in Australia.

DNA probes were used in in situ hybridisation on histological sections of oysters exposed for defined intervals to Marteilia sydneyi infection to reveal the early development of the parasite in the oyster host, Saccostrea glomerata. The initial infective stages enter through the palps and gills whereupon extrasporogonic proliferation results in the liberation of cells into surrounding connective tissue and haemolymph spaces. Following systemic dissemination, the parasite infiltrates the digestive gland and becomes established as a nurse cell beneath the epithelial cells in a digestive tubule. Here, cell-within-cell proliferation results in the eventual liberation of daughter cells from the nurse cell into spaces between adjacent epithelial cells. None of these stages had previously been described. Proliferation is associated with host responses, including haemocytic infiltration of the connective tissue and diapedesis across tubule epithelia. The responses cease as sporogenesis begins.

Biodiversity is a term applied to described the number, variety and variability of organisms. Its colloquial application is usually as a measure of species diversity of species richness. Thus, the concepts of "species" and "species boundaries" are integral to any discussion on biodiversity, and with them, the basal question of what constitutes meaningful variation. Protozoan taxonomy is an evolving mix of morphological and molecular characters, and is based largely on decisions made intuitively and arbitrarily using multiple characters. Where to draw species boundaries has become more difficult in the face of a bewildering level of variation uncovered in recent years, due largely to an increase in the resolution of our taxonomic techniques (e.g., ultrastructural and genetic studies). A major challenge for contemporary protozoan taxonomists is to update the existing systematic framework to incorporate our current level of knowledge and to decide on the relative importance of parasite morphology, genetics and biology to the concept of the protozoan "species". This task is compounded by the relative paucity of information on our endemic protozoan parasites. In Australia, even in vertebrate hosts, little is known of the biodiversity of parasitic protozoa. Not surprisingly, what knowledge we do have is linked to clinical disease, e.g., detailed knowledge of some species of coccidia and of some enteric ciliates, flagellates and amoebae of mammals. We have some knowledge of a few species of haemosporidia of reptiles and birds but, even here, molecular studies and experimental work are required to identify species boundaries. In view of these limitations, the best estimate of the biodiversity of Australia's parasitic protozoa in at least the vertebrate fauna of Australia, is that less than one third of the total species have been discovered to date.

Field and laboratory investigations into the effect of the parasitic isopod Anilocra pomacentri (Cymothoidae) on the population dynamics of the reef fish Chromis nitida (Pomacentridae) were carried out at Heron Island, Great Barrier Reef, Australia. Fish carried a single adult parasite just posterior and dorsal to the eye either to the right or to the left of the midline. The adult parasite was overdispersed among fish on patch reefs (dispersion factor, k = 0.69). Sequential field observations on a single cohort of fish showed that parasites significantly depressed growth, reproduction, and survivorship. The von Bertalanffy growth coefficients (a measure of somatic growth) were 0.10 for parasitized fish compared with 0.17 for non-parasitized fish. Female fish carrying the parasite produced only 12% of the number of eggs produced by non-parasitized fish of the same size. In the field, the mortality of infected juvenile C. nitida (LCF 15-30 mm) was estimated to be at least 88% in the first 70 days after recruitment of the fish. The mortality of uninfected recruits over the same period was 66%. In laboratory trials, the mortality associated with the infection of juvenile fish by larval parasites ranged from 78% for small fish (mean LCF 15.0 mm) to 28% for larger fish (mean LCF 24.9 mm) within 4 days of experimental infection. This is one of the few studies that evaluates the effect of a parasite on a population of fish in the field.