Occurrence of Stenurus globicephalae (Nematoda: Pseudaliidae) in the blowhole of Globicephala macrorhynchus (Cetacea: Delphinidae) in Tasmania, Australia.

Information about parasites of cetaceans in Australia is scarce and mostly opportunistic. The morphology of specimens of the metastrongyloid Stenurus globicephalae Baylis & Daubney, 1925 (Nematoda: Pseudaliidae), collected from the blowhole of a pilot whale Globicephala macrorhynchus Gray, 1846 (Cetacea: Delphinidae) off northern Tasmania, Australia, were studied. Light and scanning electron microscopical examinations enabled a detailed redescription of this nematode species, including corrections of some inaccuracies in previous species descriptions, particularly those concerning cephalic and caudal structures. The presence of numerous ventrolateral oblique muscle bands, characteristic of the males of S. globicephalae, is reported for the first time. This is the second finding of this nematode parasite, in a different host species, in Tasmania.

Characterisation of Nematoda and Digenea in selected Australian freshwater snails.

Freshwater snails are integral to local ecosystems as a primary food source for various vertebrate species, thereby contributing significantly to ecological food webs. However, their role as intermediate hosts also makes them pivotal in the transmission of parasites. In Australia, research on freshwater snails has predominantly focused on their role as intermediate hosts for livestock parasites, while there has been limited exploration of the impact of these parasites on snail health and population dynamics. The aim of this study was to determine parasitic infection in freshwater snails. This study was conducted in the south-eastern region of Australia, in 2022. A total of 163 freshwater snails from four different species were collected and examined in the Murrumbidgee catchment area in the southeastern part of Australia during the Southern Hemisphere summer and autumn months (February to May). The species included Isidorella hainesii, Glyptophysa novaehollandica, Bullastra lessoni (endemic species), and Physella acuta (an introduced species). Through the analysis of sequence data from the various regions of the nuclear ribosomal DNA, we determined that the Digenea species in this study belonged to three distinct species, including Choanocotyle hobbsi, Petasiger sp. and an unidentified species belonging to Plagiorchioidea. Additionally, analysis of the sequences from Nematoda found in this study, revealed they could be categorized into two separate taxa, including Krefftascaris sp. and an unidentified nematode closely associated with plant and soil nematodes. This research holds significant implications for the future understanding and conservation of Australian freshwater ecosystems. Most parasites found in the present study complete their life cycle in snails and turtles. As many of freshwater snail and turtle species in Australia are endemic and face population threats, exploring the potential adverse impacts of parasitic infections on snail and turtle health, is crucial for advancing our understanding of these ecosystems and also paving the way for future research and conservation efforts. While none of the native snail species in the present study have been listed as endangered or threatened, this may simply be attributed to the absence of regular population surveys.

The Presence of a Parasite in the Head Tissues of a Threatened Fish (Bidyanus bidyanus, Terapontidae) from South-Eastern Australia.

The silver perch, Bidyanus bidyanus (Mitchell) (Terapontidae) is a freshwater fish, endemic to the Murray-Darling river system in south-eastern Australia. Population declines have led to the fish being listed as critically endangered by the Australian Government. Knowledge about parasites and diseases of wild populations of freshwater fish are limited in Australia. During an examination of wild-caught silver perch, digenean mesocercaria were observed in the head tissues. A total of five of the 11 silver perch collected from the Wakool River, New South Wales, were infected with mesocercaria. All mesocercaria were found in the head tissues; no mesocercaria were found encysted in the eye lens. The mesocercaria were found to belong to the family Strigeidae based on the sequences of their internal transcribed spacer (ITS) region. The lack of comparable sequences of strigeid digeneans from Australian hosts precludes being able to determine if the mesocercaria found in this study are a new species or representatives of an already described species. However, genetic results confirm that this is a different species to other digeneans previously described from silver perch, thus increasing the number of digeneans reported from B. bidyanus to three species. The presence of digenean mesocercaria in the head tissues of a wild population of silver perch, as found in the present study, is of potential conservation significance. Given the critically endangered conservation status of B. bidyanus, and previous evidence of strigeid infection altering fish behaviour, ecology, and predation mortality, further research on the potential impacts of infection on wild populations is warranted.

Occurrence of digenean parasites in freshwater snails in the Murrumbidgee catchment area, Australia.

Freshwater snails are important hosts in the life cycles of many medically important parasites, particularly for digenetic trematodes such as liver flukes and schistosomes. The current study was conducted to determine the infection of freshwater snails with parasites that can potentially be transmitted to humans within the Murrumbidgee catchment area which is an area of widespread intensive aquaculture in Australia. A total of 116 freshwater snails, belonging to three species (Isidorella hainesii, Glyptophysa novaehollandica and Bullastra lessoni), were examined for the presence of parasites in both man-made and natural environments. The analysis of sequence data, including the internal transcribed spacers (ITS) of nuclear ribosomal DNA, small subunit (18S) ribosomal DNA, and large subunit (28S) ribosomal DNA, indicated that the collected parasites belonged to two distinct genera, namely Clinostomum and Echinostoma. It is noteworthy that species of both of these digenean parasites have the potential to be zoonotic. Cercariae of both Clinostomum and Echinostoma were observed in snails collected from aquaculture settings. It is important to highlight that infectious stages of Clinostomum  has been previously detected in edible fish within Australia. This information raises concerns regarding the potential transmission of these parasites to humans through the consumption of contaminated fish. These findings emphasize the importance of monitoring and controlling the presence of Clinostomum and Echinostoma in aquaculture environments to minimise the risk of zoonotic infections and ensure food safety. Further research and surveillance are needed to better understand the prevalence, transmission dynamics, and potential public health implications associated with these parasites in the context of aquaculture in Australia.

Infection levels of Gnathostomatidae (Nematoda) larvae in commercial fishes in north-eastern Australian waters and related food safety concerns.

The majority of research on the safety of marine edible fish has primarily focused on anisakid nematodes, neglecting the potential risks posed by other parasites, including those belonging to the family Gnathostomatidae. In Australia, there have been few reported cases of human infections with gnathostomatid parasites since 2011. However, due to the absence of a standardized diagnostic test in the country, it is believed that the actual number of infections is higher than reported. This study aimed to assess the occurrence and prevalence of infectious gnathostomatid parasites in selected commercial fish species in Australia. A total of 1947 marine fish from northern Australia, representing 9 families, 16 genera, and 30 species, were examined for gnathostomatid nematode infections. Overall, 12.3 % of the fish were found to be infected with at least one gnathostomatid larva. Among the species examined, the yellow-dabbled flounder (Branchypleura novaezeelandiae) exhibited the highest prevalence (83.3 %; n = 6) and the largest number of gnathostomatid larvae. The identification of the gnathostomatid larvae was confirmed as belonging to the genus Echinocephalus based on both morphological characteristics and sequence data. No significant correlation was observed between the prevalence, mean abundance, and mean intensity of infection with the length or weight of the examined fish species. Notably, several of the infected fish species are considered popular choices in the Australian market. Hence, it is imperative to raise awareness among relevant food safety authorities regarding the occurrence of these parasites. The findings from this study should be taken into consideration for the revision of current seafood safety protocols in the country.

ADULT TAPEWORM (PLATYHELMINTHES: CESTODA) PARASITES OF NORTH AMERICAN HERPETOFAUNA: CHECKLIST OF SPECIES AND IDENTIFICATION KEY TO FAMILIES AND GENERA.

An updated checklist of adult tapeworms (Platyhelminthes: Cestoda) that parasitize wild North American amphibians and reptiles is presented: A total of 58 species grouped in 15 genera, 5 families, and 3 orders, are registered; these infect a total of 90 species of reptiles and 88 species of amphibians in the region. An illustrated identification key for the families and genera listed is proposed.

Relationships between local variability in parasite communities of the black-spotted croaker (Protonibea diacanthus) (Teleostei: Sciaenidae) and host population structure and seasonality.

We evaluated spatial and temporal variability in parasite communities from the commercially important tropical marine fish the black-spotted croaker (Protonibea diacanthus) (Teleostei: Sciaenidae) to examine its population structure off the coast of the Northern Territory, Australia. Differences in parasite assemblage between four locations, across three seasons of the year, were used to evaluate the degree of connectivity of the sciaenid across coastal study areas. Analysis of parasite prevalence and mean intensity in these fish suggested the four sampling sites are distinct host populations. Across time, parasite assemblages at the four sites were distinct during the mid-dry (April-August) and build-up (September-November) seasons. During the wet season (December-March) there was substantial overlap in the parasite assemblages at three of the four sites indicating that fish population mixing may be occurring. Parasite assemblages at one nearshore site remained distinct across spatial and temporal scales. Our findings support the utility of parasitic organisms for elucidating the population structure of host species and reiterate the need to account for both spatial and temporal variability when performing stock discrimination analyses.

Caligid sea lice (Copepoda: Caligidae) from golden snapper Lutjanus johnii (Bloch) in Australian waters, with the recognition of Sinocaligus Shen, 1957 as a junior synonym of Caligus Müller, 1785.

Two species of sea lice are reported from the golden snapper Lutjanus johnii (Bloch) in Australian waters. One was represented by chalimus larvae, adult males and extremely slender females in which the genital complex is scarcely wider than the fourth pedigerous somite. These females are adult as they carry paired spermatophores and are identified as Caligus dussumieri Rangnekar, 1957 on the details of their appendages. Caligus dussumieri was formerly placed in the genus Sinocaligus Shen, 1957 but the characters supporting the validity of this genus are not robust, so it is here proposed to treat it as a junior subjective synonym of Caligus and transfer its species as: Caligus formicoides Redkar, Rangnekar & Murti, 1949, Caligus dussumieri Shen, 1957, Caligus caudatus (Gnanamuthu, 1950) new combination and Caligus timorensis (Izawa, 1995) new combination. All these species can be placed in the C. bonito-species group within Caligus. Caligus rivulatus Pilla, Vankara & Chikkam, 2012 is recognized as a junior subjective synonym of C. dussumieri. A new species, C. auriolus n. sp. is also described and this is placed in the C. diaphanus species-group. A key to species of this species-group is provided which indicates that C. auriolus n. sp. is most closely related to C. stromatei Krøyer, 1863 but the latter can be distinguished by the slender abdomen of the female and by the more complex myxal process on the maxilliped in the male.

A critical review of anisakidosis cases occurring globally.

A review was conducted to identify the most common causative agents of anisakidosis, the methods used for identification of the causative agents, and to summarize the sources of infection, and patients' demographics. A total of 762 cases (409 articles, inclusive of all languages) were found between 1965 and 2022. The age range was 7 months to 85 years old. Out of the 34 countries, Japan, Spain, and South Korea stood out with the highest number of published human cases of anisakidosis, respectively. This raises the question: Why are there few to no reports of anisakidosis cases in other countries, such as Indonesia and Vietnam, where seafood consumption is notably high? Other than the gastrointestinal tract, parasites were frequently found in internal organs such as liver, spleen, pancreas, lung, hiatal and epigastric hernia, and tonsils. There are also reports of the worm being excreted through the nose, rectum, and mouth. Symptoms included sore throat, tumor, bleeding, gastric/epigastric/abdominal/substernal/lower back/testicular pain, nausea, anorexia, vomiting, diarrhea, constipation, intestinal obstruction, intussusception, blood in feces, hematochezia, anemia, and respiratory arrest. These appeared either immediately or up to 2 months after consuming raw/undercooked seafood and lasting up to 10 years. Anisakidosis commonly mimicked symptoms of cancer, pancreatitis, type I/II Kounis syndrome, intussusception, Crohn's disease, ovarian cysts, intestinal endometriosis, epigastralgia, gastritis, gastroesophageal reflux disease, hernia, intestinal obstruction, peritonitis, and appendicitis. In these cases, it was only after surgery that it was found these symptoms/conditions were caused by anisakids. A range of not only mainly marine but also freshwater fish/shellfish were reported as source of infection. There were several reports of infection with >1 nematode (up to >200), more than one species of anisakids in the same patient, and the presence of L4/adult nematodes. The severity of symptoms did not relate to the number of parasites. The number of anisakidosis cases is grossly underestimated globally. Using erroneous taxonomic terms, assumptions, and identifying the parasite as Anisakis (based solely on the Y-shaped lateral cord in crossed section of the parasite) are still common. The Y-shaped lateral cord is not unique to Anisakis spp. Acquiring a history of ingesting raw/undercooked fish/seafood can be a clue to the diagnosis of the condition. This review emphasizes the following key points: insufficient awareness of fish parasites among medical professionals, seafood handlers, and policy makers; limited availability of effective diagnostic methodologies; and inadequate clinical information for optimizing the management of anisakidosis in numerous regions worldwide.

Description of two new species of Diplectanum Diesing, 1858 (Monogenea: Diplectanidae) collected from Protonibea diacanthus (Lacepède, 1802) (Teleostei: Sciaenidae) from waters off northern Australia.

Two new species of the family Diplectanidae Monticelli, 1903 from the gills of Protonibea diacanthus (Lacepède, 1802) (Teleostei: Sciaenidae) off the northern Australian coast are described. Previous studies have either morphological or genetic results, whereas this study combines morphological and advanced molecular methods to provide the first detailed descriptions for species of Diplectanum Diesing, 1858 from Australia utilising both methodologies. Two new species, Diplectanum timorcanthus n. sp. and Diplectanum diacanthi n. sp., are morphologically described and genetically characterised using the partial nuclear 28S ribosomal RNA gene (28S rRNA) and the internal transcribed spacer 1 (ITS1) partial sequence.

Occurrence and characterisation of Eustrongylides species in Australian native birds and fish.

In Australia, nematodes belonging to the genus Eustrongylides were believed to be endemic species until the late 20th century when they were all considered to be E. excisus, invalid or inquirendae. Although these nematodes have frequently been reported in Australian fish, reptiles, and birds and cause disease or mortality among them, there has been no attempt to date to characterise them genetically. Globally, also, no one has validated or defined suitable genetic markers to distinguish between species of Eustrongylides. In this study, adult Eustrongylides from little black cormorant (Phalacrocorax sulcirostris; n = 3) and larvae from mountain galaxias (Galaxias olidus, n = 2) and a Murray cod (Maccullochella peelii, n = 1), and a Murray cod-trout cod hybrids (Maccullochella peelii x Maccullochella macquariensis, n = 1) were available for morphological examination and molecular characterisation. The adult nematodes from cormorants were identified as E. excisus. Sequences of the 18S and ITS regions were then obtained for all nematodes, which were identical among all specimens (larvae and adults) and also identical to those of E. excisus available in the GenBank. However, only one base pair difference exists between the 18S sequences of E. excisus and E. ignotus, with limited sequences available in GenBank accompanied with proper morphological data for the nematodes. With that limitation in mind, identifying our specimens as E. excisus suggests spill-over - that it is an introduced parasite species that has successfully established its life cycle among Australian native species - may have occurred. Our study is the first report of E. excisus in the little black cormorant, P. sulcirostris. Our results do not exclude the possibility of the occurrence of other species of Eustrongylides, either native or exotic, in Australia. This parasite is zoonotic and with increasing demand for fish and changing dietary preferences, such as the consumption of raw or undercooked fish, its occurrence in the flesh of the fish is concerning. This parasite is also associated with anthropogenic habitat alteration affecting the reproductive success of the infected hosts. Therefore, awareness among the relevant authorities of the presence of the parasite in Australia and its adverse impact on native animals is crucial for the success of conservation plans such as fish recovery and relocation efforts.

Austraplectana extranes sp. n. (Nematoda: Cosmocercoidea) from Australian amphibians Mixophyes carbinensis Mahony, Donnellan, Richards & McDonald (Anura: Myobatrachidae) and Rhinella marina (Linnaeus) (Anura: Bufonidae).

The genus Austraplectana Baker, 1981 is a poorly known group of cosmocercoid nematodes. In the present study, a new species of Austraplectana, A. extranes sp. n., was described using both light and scanning electron microscopy, based on specimens collected from the carbine barred frog Mixophyes carbinensis Mahony, Donnellan, Richards & McDonald (Anura: Myobatrachidae) and the cane toad Rhinella marina (Linnaeus) (Anura: Bufonidae) in Australia. Austraplectana extranes sp. n. can be easily distinguished from its congener by the much longer and different morphology of tails in both sexes, the different number and arrangement of caudal papillae, the presence of single precloacal median heart-shaped papilla and large posterior protuberance with cuticular comb-like fringe in male.

Native species Maxvachonia chabaudi Mawson, 1972 (Nematoda: Cosmocercoidea) found in the invasive marine toad Rhinella marina (Linnaeus) (Anura: Bufonidae) in Australia.

The genus Maxvachonia Chabaud et Brygoo, 1960 (Ascaridomorpha: Cosmocercidae) is a poorly known group of parasitic nematodes. Species of Maxvachonia are native to Madagascar-Australo-Papuan Region, where they are known to parasitise frogs, snakes and skinks. Unfortunately, most of Maxvachonia species have been inadequately described. In the present study, we report the native species Maxvachonia chabaudi Mawson, 1972 from the intestine of the invasive marine toad Rhinella marina (Linnaeus) in Australia for the first time. We speculate that the marine toads infected with M. chabaudi are likely related to their eating skinks or the similarity in diet/habitat/ecology between the toad and the skinks. The detailed morphology of M. chabaudi was studied using light microscopy and, for the first time, scanning electron microscopy, based on the newly collected specimens. Some characters important for the specific diagnosis of M. chabaudi are reported for the first time, including each lip with distinct inner flanges, the location of vulva varying from anterior to posterior of the oesophageal bulb and the presence of single medio-ventral precloacal papilla. An identification key to the species of Maxvachonia is provided.

TONGUE WORM (PENTASTOMIDA) PARASITES OF NORTH AMERICAN HERPETOFAUNA: CHECKLIST OF SPECIES, IDENTIFICATION KEY, AND NEW STATE AND HOST RECORDS FROM MEXICO.

An updated checklist of tongue worms (Pentastomida) which parasitize wild North American amphibians and reptiles is presented: a total of 14 species grouped in 6 genera, 4 families, and 2 orders are registered; these infect a total of 58 species of reptiles and 3 amphibians in the region. An illustrated identification key for the taxa listed is proposed. Kiricephalus coarctatus (Diesing, 1860) (Porocephalidae) is recorded for the first time in the snakes Arizona elegans Kennicott, 1859 (Colubridae); Micrurus tener Baird and Girard, 1853 (Elapidae); and Bothrops asper (Garman, 1884) (Viperidae); the exotic Raillietiella taegueselfiRiley, McAllister, and Freed, 1988 (Raillietiellidae) is recorded in the exotic lizard Hemidactylus frenatus Duméril and Bibron, 1836 (Gekkonidae) for the first time, and in Hemidactylus turcicus (Linnaeus, 1758) (Gekkonidae) for the first time in Mexico, this is also the first time it is recorded in a species of lizard native of the Americas, Sceloporus cyanogenys Cope, 1885 (Phrynosomatidae), this latter record represents a parasite spillover event; finally, Porocephalus stilesiSambon, 1910 (Porocephalidae) is formally recorded for the first time in Mexico in the snake Bothrops asper.

Molecular (cox1), geographical, and host record investigation of monogeneans Mazocraes australis (Mazocraeidae), Polylabris sillaginae, and P. australiensis (Microcotylidae).

This study determines the occurrence and molecular characterisation of Monogenea from three commercially important Australian fish: Australian sardine Sardinops sagax (Jenyns), Australian anchovy Engraulis australis (White), and eastern school whiting Sillago flindersi McKay. Earlier studies have provided only morphological species identification, whereas this study combines both morphological and molecular methods. A total of 247 fish across 3 species, sourced from the New South Wales and Victorian coasts, were examined for Monogenea. A total of 187 monogenean parasites were recovered from the gills. The overall prevalence, mean intensity, and mean abundance were 34%, 2.23, and 0.78, respectively. The parasites were initially classified morphologically as three species across two families. Family Mazocraeidae was represented by Mazocraes australis Timi et al. J Parasitol 85:28-32, 1999, and family Microcotylidae by Polylabris sillaginae (Woolcock, Parasitology 28:79-91, 1936) Dillon, Hargis, and Harrises, 1983 and P. australiensis Hayward, 1996. Molecular identification of parasites was conducted through sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The fish hosts in the present study were also barcoded (mitochondrial cox1 gene) to confirm specific identities. There was no comparable cox1 sequence available in GenBank for the parasites found in the present study. However, the phylogenetic tree clustered the monogenean species identified in this study according to their familial groups of Mazocraeidae and Microcotylidae. The presence of M. australis on E. australis and S. sagax was confirmed in this study. Polylabris australiensis was only found on S. sagax but Si. flindersi was found to be a host for both Polylabris species. This study is the first to explore the mitochondrial cox1 genes of these three-monogenean species. These findings will serve as a foundation for future monogenean research in Australian waters and elsewhere.

Pathology associated with Tripaphylus Richiardi, 1878 infection (Copepoda: Sphyriidae) in wild-caught Australian blackspot sharks, Carcharhinus coatesi (Whitley, 1939), off northern Australia.

Female specimens of the newly described mesoparasitic copepod Tripaphylus squidwardi (Sphyriidae), collected from the Australian blackspot shark, Carcharhinus coatesi, off northern Australia were examined histologically. The 'encapsulated' head of the copepod was found in the ventral musculature of the throat of the shark. The head of the copepod was surrounded by a tissue capsule of unknown origin. There were signs of chronic inflammation associated with the infection, although there appeared to be no effect on the health of the shark.

Molecular characterisation of the monogenea parasites of blue mackerel Scomber australasicus (Perciformes: Scombridae) in Australian waters.

This study describes the occurrence and molecular identification of Monogenea from blue mackerel Scomber australasicus (Cuvier) (Perciformes: Scombridae), an edible fish, from Australian waters. Previous studies have provided either morphological or genetic results, whereas this study combines both methods of species identification. A total of 50 fish sourced from the waters off the south-eastern Australian coastline were examined and 71 Monogenea were recovered from the gills. The overall prevalence, mean intensity, and mean abundance were 64%, 2.22, and 1.42, respectively. Monogenea were initially classified morphologically as five species belonging to two families. Family Mazocraeidae was represented by Kuhnia scombri (Kuhn, 1829) Sproston, 1945, K. scombercolias Nasir & Fuentes Zambrano, 1983 and Pseudokuhnia minor (Goto, 1894) Rohde & Watson, 1985 and family Gastrocotylidae by Gastrocotyle kurra Unnithan, 1968 and Allogastrocotyle bivaginalis Nasir & Fuentes Zambrano, 1983. Molecular identification of Monogenea was conducted through sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. The host S. australasicus was barcoded (cox1) to confirm the specific identity. There was no comparable sequence available in GenBank for K. scombercolias. Also, limited sequences were available in GenBank for the gastrocotylid Monogenea identified in this study. However, phylogenetic analyses of cox1 sequences of the Monogenea identified in this study clustered according to their familial groups. Gastrocotyle kurra and A. bivaginalis were identified for the first-time on S. australasicus in Australian waters. This study provides the first sequencing of cox1 gene for K. scombercolias. The outcomes of the study provide a basis for future Monogenea research in Australian waters, as well as for other Scomber spp.

Are feral goats intermediate hosts for Linguatula (Pentastomida) in Australia?

Feral goats, Capra hircus (Bovidae), currently occur across 28% of Australia, and are found in all states and territories as well as some offshore islands. Feral goats are harvested for live export or processed as game meat, with feral goats making up approximately 90% of goats sent to slaughter in Australia. Nymphs of the pentastomid parasite, Linguatula serrata, are common parasites of goats elsewhere in the world, where they cause Halzoun or Marrara disease in humans through the consumption of nymphs in raw or semi-cooked edible offal. Despite being commonly encountered in cattle at slaughter in Australia, L. serrata nymphs have never been reported from feral goats in Australia. Goats at slaughter, however, commonly show infections of lymph nodes, the majority of which are diagnosed as caseous lymphadenitis caused by bacteria, although a small number have no known aetiology. Examination of 33 feral goats from locations in New South Wales and South Australia found a Linguatula sp. nymph encased in the mesenteric lymph node of one goat from the Cooma region of New South Wales. The potential risk of transmission of Linguatula sp. to humans and other domestic animals is discussed. This study has highlighted the importance of continued surveys of feral animals for infection with parasites, especially as their distribution changes.

Two new parasitic copepods of the family Sphyriidae (Copepoda: Siphonostomatoida) from Australian elasmobranchs.

Two new species of the genus Tripaphylus Richiardi in Anonymous, 1878 (family Sphyriidae) are described from elasmobranch hosts caught as bycatch within the Demersal and Timor Reef Fisheries which operate in the Northern Territory exclusive economic zone. Tripaphylus squidwardi n. sp. was collected from Carcharhinus coatesi Whitley and had a prevalence of 11.6%. Tripaphylus dippenaarae n. sp. was collected from Rhizoprionodon acutus (Rüppell) and had a prevalence of 28.2%. The new species are distinguished from existing congeneric species by the body proportions and shape of the adult female and by the arrangement of lobes on the ventral surface of the cephalothorax.

Parasites of Selected Freshwater Snails in the Eastern Murray Darling Basin, Australia.

Aquatic snails serve an important role in the ecosystem. They also play an essential role in the life cycle of many parasites as hosts and may pose risks to animal and human health. In Australia, the role of snails in the transmission of parasites of livestock is well studied. However, despite the country's unique biodiversity and wildlife, little is known about the role of snails in the transmission and survival of parasites in other ecosystems, including aquatic and aquaculture systems. This study aimed to determine the occurrence of parasites in freshwater snails in the eastern Murray Darling Basin. A total of 275 snails were collected from various localities, including aquaculture fishery ponds and natural creeks during the summer and autumn months in the southern hemisphere. Three different species of freshwater snails, all common to the area, were found, including Bullastra lessoni (n = 11), Isidorella hainesii (n = 157), and Haitia acuta (n = 107), of which 9.1%, 1.3%, and 4.7%, respectively, were found to be harboring various developmental stages of Trematoda. No other parasite was found in the examined snails. Parasites were identified as Choanocotyle hobbsi, Plagiorchis sp. and Petasiger sp. based on the sequences of their ITS2, 18S, and 28S ribosomal DNA region. Herein, we report a native parasite Choanocotyle hobbsi in an introduced snail, Haitia acuta, from both natural and aquaculture ponds. As there are no genetic sequences for adult specimens of Petasiger spp. and Plagiorchis spp. collected in Australia for comparison, whether the specimens collected in this study are the larval stage of one of the previously described species or are a new, undescribed species cannot yet be determined. Our results also suggest snails collected from aquaculture ponds may be infected with considerably more parasites.