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In a parasitological survey of fishes from Moreton Bay (southeastern Queensland, Australia), 169 teleost fishes, representing 54 species from 28 families, were examined for larval cestodes. Of these 54 species, 36 were found to be infected by metacestodes. Metacestodes were characterised by morphological and molecular data (the D1-D3 region of the 28S rDNA gene); these data were analysed in parallel to inform larval type allocation. Metacestodes collected represented eight morphological types, seven previously reported (Types I, II, IV, V, VI, VII, and X) and one novel type (Type XVI). Phylogenetic analyses were conducted to genetically match larval types to adult cestodes. Six of the eight larval types found were matched to adult forms: Type I metacestodes matched species of Phoreiobothrium Linton, 1889 (Onchobothriidae); Type II metacestodes matched species of Acanthobothrium van Beneden, 1849 (Onchobothriidae); Type IV metacestodes matched species of Scyphophyllidium Woodland, 1927 and Alexandercestus Ruhnke & Workman, 2013 (Phyllobothriidae); Type VI metacestodes matched species of Anthobothrium van Beneden, 1850 (Tetraphyllidea incertae sedis); Type X metacestodes matched species of Ambitalveolus Caira & Jensen, 2022 (Tetraphyllidea incertae sedis); and Type XVI metacestodes matched species of Platybothrium Linton, 1890 (Onchobothriidae). Based on phylogenetic topology, Type V metacestodes are inferred to match Pedibothrium Linton, 1909 (Balanobothriidae) and Type VII metacestodes are inferred to match Spongiobothrium Linton, 1889 (Rhinebothriidae). These findings support and extend the unified morphological type system proposed previously, but suggest that morphological types will ultimately be informative to identify metacestodes to a group of related genera rather than any distinct genus., (© 2024. The Author(s).)

We report nine species of the Schistorchiinae Yamaguti, 1942 (Apocreadiidae Skrjabin, 1942) from Indo-Pacific marine fishes. Molecular data (ITS2 and 28S rDNA and cox1 mtDNA) are provided for all species and the genus-level classification of the subfamily is revised. For Schistorchis Lühe, 1906, we report the type-species Sch. carneus Lühe, 1906 and Sch. skrjabini Parukhin, 1963. For Sphinteristomum Oshmarin, Mamaev & Parukhin, 1961 we report the type-species, Sph. acollum Oshmarin, Mamaev & Parukhin, 1961. We report and re-recognise Lobatotrema Manter, 1963, for the type and only species, L. aniferum Manter, 1963, previously a synonym of Sph. acollum. Lobatotrema aniferum is phylogenetically distant from, but morphologically similar to, Sph. acollum and Lobatotrema is recognised as a 'cryptic genus'. We propose Blendiella n. gen. for B. trigintatestis n. sp. and B. tridecimtestis n. sp. These species are broadly consistent with the present morphological concept of Schistorchis but are phylogenetically distant from the type-species; a larger number of testes and some other subtle morphological characters in species of Blendiella serve to distinguish the two genera. We report three species of Paraschistorchis Blend, Karar & Dronen, 2017: P. stenosoma (Hanson, 1953) Blend, Karar & Dronen, 2017 (type-species), P. seychellesiensis (Toman, 1989) Blend, Karar & Dronen, 2017, and P. zancli (Hanson, 1953) Blend, Karar & Dronen, 2017. Lobatotrema aniferum, P. stenosoma, and Sch. carneus each have two distinct cox1 populations either over geographical range or in sympatry. Available evidence suggests that most of these species, but not all, are widespread in the tropical Indo-Pacific., (© 2023. The Author(s).)

Integration of morphological and molecular approaches to species delineation has become an essential part of digenean trematode taxonomy, particularly when delimiting cryptic species. Here, we use an integrated approach to distinguish and describe two morphologically cryptic species of Hysterolecitha Linton, 1910 (Trematoda: Lecithasteridae) from fishes of Moreton Bay, Queensland, Australia. Morphological analyses of Hysterolecitha specimens from six fish species demonstrated a complete overlap in morphometric data with no reliable differences in their gross morphological characters that suggested the presence of more than one species. Distinctions in ITS2 rDNA and cox1 mtDNA sequence data for corresponding specimens suggested the presence of two forms. A principal component analysis on an imputed dataset showed clear separation between the two forms. These two forms are partially separated on the basis of their host's identity. Therefore, we describe two morphologically cryptic species: Hysterolecitha melae n. sp. from three species of Abudefduf Forsskål and one species of Parma Günther (Pomacentridae), with the Bengal sergeant, Abudefduf bengalensis (Bloch), as the type-host; and Hysterolecitha phisoni n. sp. from species of Pomacentridae (including A. bengalensis), Pomatomidae and Siganidae, with the black rabbitfish, Siganus fuscescens (Houttuyn), as the type-host., (© 2023. The Author(s).)

Plesiochorus Looss, 1901 is a genus of Gorgoderidae infecting the urinary bladders of marine turtles globally. Currently, just two morphologically similar species are recognised, Plesiochorus cymbiformis (Rudolphi, 1819) Looss, 1901 and Plesiochorus elongatus Pigulevsky, 1953, which have been distinguished by molecular data and subtle morphological differences. Here we describe a new species, Plesiochorus irwinorum n. sp., infecting hawksbill turtles (Eretmochelys imbricata (L.)), which is primarily distinguished from the other two species of Plesiochorus on the basis of ITS2, cox1 and 28S sequence data. Morphometric data for specimens examined during this study overlap between P. cymbiformis and P. irwinorum n. sp. for every measured feature, rendering them functionally cryptic. However, principal components analysis clearly distinguishes the two species. Additionally, we report new specimens of P. cymbiformis, and provide new sequence data for specimens from Australian loggerhead (Caretta caretta (L.)) and hawksbill turtles. There is little understanding of the host-specificity or geographical distribution of the three species of Plesiochorus, and it remains possible that some of the previously reported sequences have been attributed to the wrong species., (© 2022. The Author(s).)

A new cryptogonimid trematode, Siphoderina hustoni n. sp., is reported, collected off Lizard Island, Queensland, Australia, from the Maori snapper Lutjanus rivulatus (Cuvier). The new species is moderately distinctive within the genus. It is larger and more elongate than most other species of Siphoderina Manter, 1934, has the shortest forebody of any, a relatively large ventral sucker, a long post-testicular zone, and is perhaps most recognisable for the substantial space in the midbody between the ventral sucker and ovary devoid of uterine coils and vitelline follicles, the former being restricted to largely posterior to the ovary and the latter distributed from the level of the anterior testis to the level of the ovary. In phylogenetic analyses of 28S ribosomal DNA, the new species resolved with the other nine species of Siphoderina for which sequence data are available, all of which are from Queensland waters and from lutjanid and haemulid fishes. Molecular barcode data were also generated, for the ITS2 ribosomal DNA and cox1 mitochondrial DNA markers. The new species is the first cryptogonimid known from L. rivulatus and the first metazoan parasite reported from that fish in Australian waters., (© 2022. The Author(s).)

A new species of lepocreadiid, Opechonoides opisthoporus n. sp., is described infecting 12 pomacentrid fish species from the Great Barrier Reef, Australia, with Abudefduf whitleyi Allen & Robertson as the type-host. This taxon differs from the only other known member of the genus, Opechonoides gure Yamaguti, 1940, in the sucker width ratio, cirrus-sac length, position of the testes, position of the pore of Laurer's canal, and relative post-testicular distance. The new species exhibits stenoxenic host-specificity, infecting pomacentrids from seven genera: Abudefduf Forsskål, Amphiprion Bloch & Schneider, Neoglyphidodon Allen, Neopomacentrus Allen, Plectroglyphidodon Fowler & Ball, Pomacentrus Lacépède and Stegastes Jenyns. Phylogenetic analyses of 28S rDNA sequence data demonstrate that O. opisthoporus n. sp. forms a strongly supported clade with Prodistomum orientale (Layman, 1930) Bray & Gibson, 1990. The life cycle of this new species is partly elucidated on the basis of ITS2 rDNA sequence data; intermediate hosts are shown to be three species of Ctenophora. New host records and molecular data are reported for Lepocreadium oyabitcha Machida, 1984 and Lepotrema amblyglyphidodonis Bray, Cutmore & Cribb, 2018, and new molecular data are provided for Lepotrema acanthochromidis Bray, Cutmore & Cribb, 2018 and Lepotrema adlardi (Bray, Cribb & Barker, 1993) Bray & Cribb, 1996. Novel cox1 mtDNA sequence data showed intraspecific geographical structuring between Heron Island and Lizard Island for L. acanthochromidis but not for L. adlardi or O. opisthoporus n. sp., (© 2022. The Author(s).)

We report on Neoechinorhynchus aldrichettae Edmonds, 1971 (Acanthocephala: Neoechinorhynchidae), obtained from yellow-eye mullet Aldrichetta forsteri (Valenciennes) (Mugiliformes: Mugilidae) from the Huon River, Tasmania, Australia. We provide new 18S and 28S rDNA gene sequence data for N. aldrichettae, assess its phylogenetic position relative to other species of Neoechinorhynchus and provide an updated morphological account of this species including detail of features omitted in the type-description, specifically of the apical organ, a collar at the base of the neck and a para-receptacle structure associated with the proboscis receptacle. We determine that eggs in this species are ovoid, without polar prolongations of fertilisation membrane, which permits assignment of N. aldrichettae to the subgenus Neoechinorhynchus. Our phylogenetic analyses place N. (N.) aldrichettae in a clade with other species of Neoechinorhynchus which parasitise mullets in marine and estuarine waters. We find that, in terms of monophyletic clades, the current subgeneric classification system for Neoechinorhynchus is not reflected in our phylogenetic analyses., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

We report eight species of Lintonium from tetraodontiform fishes from Australian waters and describe six of them as new. Two species are described from tetraodontids from the Great Barrier Reef (GBR): Lintonium kostadinovae n. sp. from Arothron nigropunctatus (Bloch & Schneider) and Arothron hispidus (Linnaeus); and Lintonium droneni n. sp. from A. nigropunctatus. Two species are described from temperate monacanthids: Lintonium crowcrofti n. sp. from Meuschenia hippocrepis (Quoy & Gaimard) and Meuschenia freycineti (Quoy & Gaimard) off Tasmania and from M. hippocrepis off Glenelg, South Australia and off Fremantle, Western Australia; and Lintonium blendi n. sp. from M. hippocrepis off Stanley, Tasmania. The final two new species are described from tropical monacanthids: Lintonium currani n. sp. from Cantherhines pardalis (Rüppell) from Ningaloo Reef, Western Australia; and Lintonium madhaviae n. sp. from Amanses scopas (Cuvier) from the southern GBR. Two previously described species are reported from tetraodontids: Lintonium pulchrum (Johnston, 1913) Yamaguti, 1954 from Arothron stellatus (Anonymous), A. hispidus, A. manilensis (Marion de Procé) and Lagocephalus lunaris (Bloch & Schneider) from the GBR and southern Queensland; and Lintonium consors (Lühe, 1906) Crowcroft, 1950 from A. nigropunctatus from the southern GBR. Sequence data for three markers (ITS2 and 28S rDNA and cox1 mtDNA) for six of the eight species (L. crowcrofti n. sp., L. currani n. sp., L. droneni n. sp., L. kostadinovae n. sp., L. madhaviae n. sp. and L. pulchrum) are the first for the genus and distinguish each species unambiguously. Many records of species of Lintonium, especially widespread records of the type species, L. vibex (Linton, 1900) Stunkard & Nigrelli, 1930, remain to be clarified. A key finding of the present study is that three fish species (A. hispidus, A. nigropunctatus and M. hippocrepis) are identified as harbouring either two or three species of Lintonium at individual localities., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Ankistromeces Nolan & Cribb, 2004 and Phthinomita Nolan & Cribb, 2006 are sister genera of threadlike blood flukes (Trematoda: Aporocotylidae) infecting teleost fishes of the tropical Indo-west Pacific. Here, we report new collections of these genera from Australia, Indonesia, and Japan. A new species of Ankistromeces, Ankistromeces kawamurai n. sp., is described from Siganus spinus (Linnaeus) off Okinawa, Japan, and a new species of Phthinomita, Phthinomita abdita n. sp., from Choerodon cephalotes (Castelnau), in Moreton Bay, Australia; the new species are morphologically cryptic within their respective genera and are delineated by molecular and ecological data. Ankistromeces olsoni Nolan & Cribb, 2006 is reported from Siganus fuscescens (Houttuyn) off Heron Island (southern Great Barrier Reef), Lizard Island (northern Great Barrier Reef), and Okinawa and Wakayama Prefectures, Japan and from Siganus spinus (Linnaeus) from off Bali, Indonesia. Ankistromeces mariae Nolan & Cribb, 2004 is re-reported from the type-host, Meuschenia freycineti (Quoy & Gaimard), from a new location, Gypsy Bay, Tasmania. Phthinomita poulini Nolan & Cribb, 2006 is re-reported from its type-locality, Lizard Island, from a range of mullids, including five new host species, and its range is extended to include Moreton Bay. Phthinomita symplocos Nolan & Cribb, 2006 is reported from Bali and P. hallae Nolan & Cribb, 2006, P. jonesi Nolan & Cribb, 2006, P. littlewoodi Nolan & Cribb, 2006, and P. munozae Nolan & Cribb, 2006 are each re-reported from their type-host and type-localities. New cox1 mtDNA data were generated for all known species of these two genera from new and archival material. Analyses of these data enabled an evaluation of all known Phthinomita species; P. robertsthomsoni Nolan & Cribb, 2006 is synonymised with P. adlardi Nolan & Cribb, 2006, and P. brooksi Nolan & Cribb, 2006 is synonymised with P. sasali Nolan & Cribb, 2006. We highlight the failure of ITS2 data to delineate closely related aporocotylid species. In contrast, cox1 sequence data are proving reliable and effective in this context and we recommend their incorporation in future studies of blood fluke taxonomy., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

The Monorchiidae Odhner, 1911 are well represented in tropical and subtropical marine fishes worldwide but rarely reported from the Lutjanidae, an important family of tropical fishes that prey mainly on demersal fishes, decapods and cephalopods. Here, we report the first monorchiid from a lutjanid in Australian waters, Retroporomonorchis pansho n. g., n. sp. in Lutjanus fulvus (Forster), off Lizard Island on the northern Great Barrier Reef. It is morphologically and phylogenetically distinct among known monorchiids, resolves within the Monorchiinae Odhner, 1911, and is characterised by a relatively large ventral sucker, a sinistral genital pore immediately posterior to the ventral sucker, unfilamented eggs, a single testis, and vitelline follicles restricted to the level of the gonads. We assessed all previous records of monorchiids from lutjanid fishes and found only one to be convincing, that of Infundiburictus overstreeti (Gupta & Gupta, 1990) Wee, Cutmore, Pérez-del-Olmo & Cribb, 2020 from Lutjanus monostigma (Cuvier) in the Bay of Bengal. Another, Monorcheides xishaensis Shen, 1985, from Lutjanus argentimaculatus (Forsskål) in the Paracel Islands, South China Sea, is here recognised as a cryptogonimid, and is synonymised with Siphoderina asiatica Gu & Shen, 1979. In the remaining reports, the identity of the host is either ambiguous or doubtful, or the identity of the worm is not supported with sufficient evidence.

Three new species of the family Bucephalidae Poche, 1907 (Trematoda: Digenea) are described from the yellowtail pike, Sphyraena obtusata Cuvier (Sphyraenidae), from Moreton Bay, Queensland, Australia. The three species are morphologically consistent with the present broad concept of the genus Bucephalus Baer, 1827, but significant phylogenetic and ecological differences relative to the type-species of Bucephalus require the proposal of a new genus. Aenigmatrema n. g. is proposed for A. undecimtentaculatum n. sp. (type-species), A. inopinatum n. sp. and A. grandiovum n. sp. In addition, based on morphological, ecological and biogeographical similarities, we recombine two existing species of Bucephalus as Aenigmatrema kaku (Yamaguti, 1970) n. comb. and Aenigmatrema sphyraenae (Yamaguti, 1952) n. comb. Although the three species described in this study are extremely morphologically similar, they can be differentiated from each other, and from A. kaku and A. sphyraenae, morphometrically on the basis of egg size, tentacle number and a combination of the caecum and vitelline field lengths. Complete ITS2 rDNA, partial 28S rDNA and partial cox1 mtDNA sequence data were generated for the three new species, which formed a well-supported clade in all 28S phylogenetic analyses. An expanded phylogenetic tree for the subfamily Bucephalinae Poche, 1907 is presented, demonstrating unresolved issues with the morphology-based taxonomy of the subfamily. The three largest genera, Bucephalus, Rhipidocotyle Diesing, 1858 and Prosorhynchoides Dollfus, 1929 remain extensively polyphyletic, indicating the need for significant further systematic revision.

Prior to the present study, species of the trematode family Monorchiidae Odhner, 1911 had been reported from four of the ten families of tetraodontiform fishes: the Balistidae, Monacanthidae, Ostraciidae and Tetraodontidae. Here we report the first monorchiid from the family Triacanthidae, Pseudohurleytrema yolandae n. sp. infecting Tripodichthys angustifrons (Hollard), from Moreton Bay, Queensland, Australia. The species conforms well to the morphological concept of the subfamily Hurleytrematinae Yamaguti, 1958, and the genus Pseudohurleytrema Yamaguti, 1954, in the possession of filamented eggs, a bipartite terminal organ, and a unipartite seminal vesicle. Relative to the other three recognised species of Pseudohurleytrema, the present species is distinctive in the size of the testis and eggs, position of the ovary, and the form of the vitellarium and excretory vesicle. We consider Pseudohurleytrema magnum Kaikabad & Bilqees in Bilqees, 1991 as a species inquirenda. Sequence data for the 28S ribosomal RNA gene and cox1 mitochondrial gene were generated for P. yolandae, providing the first molecular data for the genus. Phylogenetic analysis showed that P. yolandae does not form a clade with the other three hurleytrematine genera for which there are molecular data (Helicometroides Yamaguti, 1934, Hurleytrematoides Yamaguti, 1953 and Provitellus Dove & Cribb, 1998), forming a poorly-supported clade with Proctotrema addisoni Searle, Cutmore & Cribb, 2014 within the clade of the subfamily Monorchiinae Odhner, 1911. The four hurleytrematine genera resolved as four distinct clades, indicating that the current subfamilial classification requires comprehensive revision.

Four new monorchiid trematodes are reported from Moreton Bay, Australia; three new species of Provitellus Dove & Cribb, 1998 and one species of Ovipusillus Dove & Cribb, 1998, are described from Gnathanodon speciosus (Forsskål) (Carangidae), the golden trevally. Provitellus chaometra n. sp., Provitellus infrequens n. sp. and Provitellus infibrova n. sp. differ significantly from the only other species of this genus, Provitellus turrum Dove & Cribb, 1998, in the structure of the eggs, vitelline follicles and terminal organ. The four species are united, however, in the possession of short caeca and a long genital atrium, a combination not reported previously. Ovipusillus geminus n. sp. strongly resembles its only congener, Ovipusillus mayu Dove & Cribb, 1998, but differs in the morphology of the diverticulum in the cirrus-sac and the shape of the pharynx. Complete ITS2 and partial 28S rDNA sequence data were generated for all four species, as well as for two known species of Hurleytrematoides Yamaguti, 1953, Hurleytrematoides galzini McNamara & Cribb, 2011 and Hurleytrematoides loi McNamara & Cribb, 2011. These sequences were analysed with those for other monorchiids available on GenBank, and phylogenetic analyses showed that the four species of Provitellus and two species of Ovipusillus each form strongly supported clades. As with previous monorchiid phylogenetic studies, however, the overall resolution of the phylogeny of the Monorchiidae is poor.

Eight species of the trematode family Bucephalidae Poche, 1907 are reported from teleost fishes in Moreton Bay, Queensland, Australia. Heterobucephalopsis yongi n. sp. is described from Gymnothorax eurostus (Muraenidae); the new form is distinguished from its congeners in the possession of a tiny cirrus-sac relative to body length, the length of the caecum, the position of the mouth and pharynx, and the position of the testes and ovary. Two known species of Dollfustrema Eckmann, 1934, D. durum Nolan, Curran, Miller, Cutmore, Cantacessi & Cribb, 2015 and D. gibsoni Nolan & Cribb, 2010, are reported from Gymnothorax pseudothyrsoideus (Bleeker) (Muraenidae); although both species were described from Australian waters, this represents the first reports from Moreton Bay and G. pseudothyrsoideus. Four species of Prosorhynchus Odhner, 1905 are reported, including one new, P. brayi n. sp., which is described from Epinephelus coioides (Hamilton) (Serranidae); P. brayi n. sp. is distinguished from its congeners in the possession of vitelline follicles in a confluent arc distinctly posterior to a conical rhynchus, uterine coils that do not extend anterior to the vitelline arc, contiguous testes, a cirrus-sac that reaches anteriorly to at least the level of the posterior testis and a short excretory vesicle. Three known species of Prosorhynchus are reported from Australia, for the first time: P. luzonicus Velasquez, 1959 and P. maternus Bray & Justine, 2006 from E. coioides and Prosorhynchus platycephali (Yamaguti, 1934) Srivastava, 1938 from Ambiserrula jugosa (McCulloch) and Inegocia japonica (Cuvier) (Platycephalidae). Skrjabiniella Issaitschikow, 1928 is re-recognised for new specimens of Skrjabiniella uniporus (Ozaki, 1924) n. comb. collected from Conger cinereus Rüppell (Congridae); three additional species of Prosorhynchus are considered members of this genus, two of which are synonymised with S. uniporus.

Parasitological examination of elasmobranchs of Moreton Bay, Queensland, Australia, resulted in the discovery of cestodes belonging to several armed genera of the Tetraphyllidea and Onchoproteocephalidea. Two new tetraphyllideans, Yorkeria moretonensis n. sp. and Yorkeria williamsi n. sp., are described from Chiloscyllium cf. punctatum (Hemiscylliidae). Yorkeria moretonensis n. sp. differs from its congeners in the possession of vitelline follicles that are discontinuous in the region of the ovary and in the length of its pedicels. Yorkeria williamsi n. sp. is most similar to Y. parva Southwell, 1927, but has larger, oval bothridia, longer pedicels and differences in the sizes of the scolex hooks. Yorkeria longstaffae Caira, Jensen & Rajan, 2007 is reported from Moreton Bay for the first time, and Spiniloculus mavensis Southwell, 1925 is re-reported from the type-locality and likely type-host (Moreton Bay and Chiloscyllium cf. punctatum, respectively), over 90 years after its original description. Six known onchoproteocephalideans, Acanthobothrium cannoni Campbell & Beveridge, 2002, A. chisholmae Campbell & Beveridge, 2002, A. ocallaghani Campbell & Beveridge, 2002, A. margieae Fyler, 2011, Megalonchos shawae Caira, Reyda & Mega, 2007 and M. sumansinghai Caira, Reyda & Mega, 2007, are reported from Moreton Bay for the first time, representing significant range extensions for all species.

Opistholebetine opecoelids are reported following examination of 1,041 individual tetraodontiform fishes, comprising 60 species and seven families, collected in Australian waters between 1986 and 2018. Nine species consistent with Opistholebes Nicoll, 1915, Heterolebes Ozaki, 1935 or Maculifer Nicoll, 1915 were recovered. However, phylogenetic analysis of sequence data, generated for some of these species, suggested that five genera, not three, are required to adequately accommodate these taxa. Thus, the concept and composition for each is revised, Pseudoheterolebes Yamaguti, 1959 nec Gupta, 1968 is resurrected and Parallelolebes n. g. is proposed. Of the nine species examined, five are new. Four new species are from fishes endemic to subtropical and temperate Australian waters for which no trematodes have previously been reported: Pa. australis n. sp. and Ps. corazonae n. sp. from the slender-spined porcupinefish Diodon nicthemerus Cuvier (Diodontidae) off Stanley, Tasmania; Pa. virilis n. sp. from the horse-shoe leatherjacket Meuschenia hippocrepis (Quoy & Gaimard) (Monacanthidae) off Stanley; and Ps. stellaglobulus n. sp. from the threebar pocupinefish Dicotylichthys punctulatus Kaup (Diodontidae) in Moreton Bay, south-east Queensland. The fifth new species is M. diodontis n. sp., collected from the spotted porcupinefish Diodon hystrix Linnaeus and the blackblotched porcupinefish D. liturosus Shaw, in tropical waters on the Great Barrier Reef. Species reported previously include the type-species of Opistholebes, O. amplicoelus Nicoll, 1915 from the rough golden puffer Lagocephalus lunaris (Bloch & Schneider) (Tetraodontidae) and the common toadfish Tetractenos hamiltoni (Richardson) (Tetraodontidae) in Moreton Bay, and three species reported for the first time from fishes in Australian waters: H. maculosus Ozaki, 1935, Pa. elongatus Ozaki, 1937 n. comb. and Ps. diodontis (Cable, 1956) n. comb., each from both D. hystrix and D. liturosus on the Great Barrier Reef. Following the revisions, Opistholebes is recognised for two species, Heterolebes for five, Maculifer for eight, Pseudoheterolebes for five and Parallelolebes for three.

We review species of the genus Lepotrema Ozaki, 1932 from marine fishes in the Indo-West Pacific. Prior to the present study six species were recognised. Here we propose eight new species on the basis of combined morphological and molecular analysis: Lepotrema acanthochromidis n. sp. ex Acanthochromis polyacanthus from the Great Barrier Reef (GBR); Lepotrema hemitaurichthydis n. sp. ex Hemitaurichthys polylepis and H. thompsoni from Palau and French Polynesia; Lepotrema melichthydis n. sp. ex Melichthys vidua from Palau and the GBR; Lepotrema amansis n. sp. ex Amanses scopas from the GBR; Lepotrema cirripectis n. sp. ex Cirripectes filamentosus, C. chelomatus and C. stigmaticus from the GBR; Lepotrema justinei n. sp. ex Sufflamen fraenatum from New Caledonia; Lepotrema moretonense n. sp. ex Prionurus microlepidotus, P. maculatus and Selenotoca multifasciata from Moreton Bay; and Lepotrema amblyglyphidodonis n. sp. ex Amblyglyphidodon curacao and Amphipron akyndynos from the GBR. We also report new host records and provide novel molecular data for two known species: Lepotrema adlardi Bray, Cribb & Barker, 1993 and Lepotrema monile Bray & Cribb, 1998. Two new combinations are formed, Lepotrema cylindricum (Wang, 1989) n. comb. (for Preptetos cylindricus) and Lepotrema navodonis (Shen, 1986) n. comb. (for Lepocreadium navodoni). With the exception of a handful of ambiguous records, the evidence is compelling that the host-specificity of species in this genus is overwhelmingly oioxenous or stenoxenous. This renders the host distribution in three orders and ten families especially difficult to explain as many seemingly suitable hosts are not infected. Multi-loci molecular data (ITS2 rDNA, 28S rDNA and cox1 mtDNA) demonstrate that Lepotrema is a good generic concept, but limited variability in sequence data and differences in phylogenies produced for different gene regions make relationships within the genus difficult to define.

Two new species of Bacciger Nicoll, 1914 (Faustulidae) are described infecting clupeids collected from the waters off Queensland, Australia; Bacciger minor n. sp. is described from Herklotsichthys castelnaui (Ogilby) in Moreton Bay, southern Queensland and Bacciger major n. sp. is described from Herklotsichthys quadrimaculatus (Rüppell) collected off Lizard Island, on the northern Great Barrier Reef. The two species both differ from previously described species of Bacciger in the combination of their generally elongate bodies, an entire rather than deeply lobed ovary, vitelline follicles that reach to at least the intestinal bifurcation, instead of restricted to further posteriorly but principally distributed in the hindbody, and intestinal caeca extending posteriorly well past the ventral sucker. The two new species have non-overlapping size ranges and differ in their sucker ratios, the distribution of the vitelline follicles and in the shape of the cirrus-sac. ITS2 and 28S rDNA sequence data distinguish the two new species unambiguously. Phylogenetic analysis of available 28S data show they are most closely related to Pseudobacciger cheneyae Sun, Bray, Yong, Cutmore & Cribb, 2014, also recorded off Lizard Island. These are the first faustulids reported from species of Herklotsichthys Whitley, but overall members of the Clupeidae undoubtedly harbours the richest faustulid fauna of any fish family. Baccigeroides ovatus (Price, 1934) n. comb. is proposed for Bacciger ovatus (Price, 1934) Bray & Gibson, 1980 (syn. B. opisthonema Nahhas & Cable, 1964) based on the position of the genital pore being far anteriorly removed from the ventral sucker.

The nematode Philometra pellucida (Jägerskiöld, 1893) (Philometridae) is redescribed from female specimens obtained from the abdominal cavity of the marine tetraodontiform fish (blackspotted puffer) Arothron nigropunctatus (Bloch & Schneider) (Tetraodontidae) off Lizard Island, Australia and off Okinawa, Japan. This is just the second record of this parasite since its description 125 years ago. Light and scanning electron microscopical examination of these nematodes revealed some taxonomically important, previously unreported morphological features, such as the number and arrangement of cephalic papillae, presence of the oesophageal cell nucleus and the size of first-stage larvae in the uterus. This new report of P. pellucida infecting A. nigropunctatus off Australia and Japan represents new host and geographical records. A key to the species of Philometra Costa, 1845 parasitising tetraodontiform fishes is provided.

A survey of the trematode fauna of lutjanid fishes off the east coast of Queensland (QLD), Australia revealed the presence of two species of Neometadena Hafeezullah & Siddiqi, 1970 (Digenea: Cryptogonimidae). Neometadena paucispina n. sp. is described from the intestine and pyloric caeca of Lutjanus fulviflamma (Forsskål) and L. russellii (Bleeker) from Moreton Bay, in southeast QLD. Specimens of the type- and only other species, N. ovata (Yamaguti, 1952) Miller & Cribb, 2008, were recovered from L. carponotatus (Richardson), L. fulviflamma, L. fulvus (Forster), L. russellii, and L. vitta (Quoy & Gaimard) off Lizard Island, on the northern Great Barrier Reef (GBR). Neometadena paucispina is distinguished from N. ovata in having fewer oral spines (55-65 vs 67-80). Alignment of novel molecular data for these two taxa revealed that they differ consistently by 13 nucleotides (1.5%) over the partial large subunit (LSU), 34 nucleotides (6.6%) over the internal transcribed spacer 1 (ITS1), 0 nucleotides over the 5.8S, and 21 nucleotides (7.3%) over the ITS2 rDNA regions. Despite relatively large samples of L. carponotatus, L. fulviflamma and L. russellii from three distinct locations along the east coast of QLD (i.e. Moreton Bay in the south, Heron Island in central QLD and Lizard Island in northern QLD), these two species have been found at only one site each with neither species at Heron Island. These distributions are discussed in the context of the wide distribution of other cryptogonomid species in the same hosts elsewhere in the Indo-West Pacific.

Digeneans of the lepocreadioid families Lepocreadiidae Odhner, 1905 and Aephnidiogenidae Yamaguti, 1934 from Moreton Bay, off southern Queensland, Australia, are recorded, along with the erection of a new family, Gibsonivermidae. Molecular data were generated for all representatives of these families collected during this study and a phylogram for members of the superfamily was generated based on the partial 28S rDNA dataset, placing these species in context with those previously sequenced. This phylogenetic analysis demonstrates that the monotypic Gibsonivermis Bray, Cribb & Barker, 1997 is isolated from all other lepocreadioids and supports the erection of Gibsonivermidae n. fam., which is defined morphologically, based particularly on the uniquely elongated male terminal genitalia, the distribution of the uterus in the forebody and the presence of a uroproct. Mobahincia teirae n. g., n. sp. is reported from Platax teira (Forsskål) in Moreton Bay and off Heron Island and New Caledonia. Recognition of this new genus is based on molecular results and the combination of caeca abutting the posterior body wall and the lack of an anterior body scoop or flanges. The following lepocreadioid species are reported from Moreton Bay for the first time: Bianium arabicum Sey, 1996 in Lagocephalus lunaris (Bloch & Schneider), Diploproctodaeum cf. monstrosum Bray, Cribb & Justine, 2010 in Arothron hispidus (Linnaeus), Multitestis magnacetabulum Mamaev, 1970 and Neomultitestis aspidogastriformis Bray & Cribb, 2003 in Platax teira and Opechona austrobacillaris Bray & Cribb, 1998 in Pomatomus saltatrix (Linnaeus). Bianium plicitum (Linton, 1928) is reported from Torquigener squamicauda (Ogilby) for the first time. Sequences of newly collected specimens of Austroholorchis sprenti (Gibson, 1987) indicate that the species forms a clade with other members of the Aephnidiogenidae, agreeing with its morphology. The phylogenetic status of all newly sequenced species is discussed.

Two species of the trematode genus Phyllodistomum Braun, 1899 (Gorgoderidae) are reported infecting teleost fishes from Moreton Bay, Queensland, Australia. Phyllodistomum hyporhamphi n. sp. is described from two species of garfishes (Hemiramphidae), Hyporhamphus regularis ardelio (Whitley) and H. australis (Steindachner). The new species differs from other marine species of Phyllodistomum in possessing a forebody length less than half that of the body, a body length to width ratio < 4:1, an oral sucker width to ventral sucker width ratio > 1:1 and < 2:1, 7-9 strong, marginal undulations on each side of the body and large, slightly lobed vitelline masses. Phyllodistomum pacificum Yamaguti, 1951 is reported, for the first time in Australian waters, from Pantolabus radiatus (MacLeay) (Carangidae). The new material agrees closely with the original description of P. pacificum, in Carangoides equula (Temminck & Schlegel) off Hamazima, Mie Prefecture, Japan, although the specimens from Moreton Bay are larger than those of the original description (4,575-5,338 × 1,111-1,328 vs 2,200-3,100 × 570-930 μm). Cetiotrema carangis (Manter, 1947) Manter, 1970 is found to be a synonym of Cetiotrema carangis (MacCallum, 1913) Williams & Bunkley-Williams, 1996 and the species is formally moved to Phyllodistomum as P. carangis (MacCallum, 1913) n. comb. Phylogenetic analyses of 28S rDNA data showed that the six marine species of Phyllodistomum for which molecular data are available form a strongly-supported clade.

Two monorchiid species are reported from the freckled goatfish, Upeneus tragula Richardson, from Moreton Bay, Queensland, Australia. Specimens of a species new to science were most morphologically similar to species of the genus Timonia Bartoli & Prevot, 1966, but significant differences in the arrangement of the testes (symmetrical vs oblique) and morphology of the terminal organ (bipartite vs unipartite) necessitate the proposal of a new genus; Madhavia n. g. is proposed for M. fellaminutus n. sp. Specimens of the second species are identified as Parachrisomon delicatus (Manter & Pritchard, 1964) Madhavi, 2008, extending its known range from Hawaii to Australia. Complete ITS2 and partial 28S rDNA sequence data were generated for both species and analysed with those for other monorchiids available on GenBank. Phylogenetic analyses of the 28S rDNA dataset showed that both genera are distinct from other sequenced monorchiids, but overall the resolution between genera is poor and more sequence data are required to elucidate relationships within the family. We propose to transfer Timonia stunkardi (Ahmad, 1985) and Timonia vinodae (Ahmad, 1987) to the genus Neotimonia Madhavi, 2008, as Neotimonia stunkardi (Ahmad, 1985) n. comb. and Neotimonia vinodae (Ahmad, 1987) n. comb. Additionally, we were unable to locate any literature on Parachrisomon brotulidorum (Toman, 1973) Madhavi, 2008 and consider this species as nomen nudum.

Choerodonicola Cribb, 2005 is a minor genus of opecoelid trematodes defined for species with exceptionally small eggs but otherwise generalised morphology. Four species are currently recognised, all from fishes collected in Japanese waters but each from different perciform families: a labrid, a scarid, a sparid and pinguipeds. We report on a new species, Choerodonicola arothokoros n. sp., from the blue-barred parrotfish Scarus ghobban Forsskål (Scaridae) collected in subtropical waters of Moreton Bay, south-east Queensland, Australia. Using genetic sequence data for the ITS2 rDNA marker, we matched adult C. arothokoros to intramollsucan stages discovered in an intertidal gastropod Herpetopoma atratum (Gmelin) (Vetigastropoda: Chilodontidae) collected in close proximity to the fish hosts. Notably, the cercariae lack a penetration stylet and are among the smallest known in the Opecoelidae. We provide the first assessment of the phylogenetic position of Choerodonicola based on sequence data generated for the phylogenetically informative 18S and 28S rRNA coding regions, for C. arothokoros and also C. renko Machida, 2014, which we recollected from the yellowback seabream Dentex hypselosomus Bleeker from the fish market in Minabe, Wakayama Prefecture, Japan. In our analyses, species of Choerodonicola resolved to neither of the major marine Plagioporinae (sensu lato) clades, clustering instead with Trilobovarium parvvatis Martin, Cutmore & Cribb, 2017, Podocotyloides parupenei (Manter, 1963) Pritchard, 1966 and Macvicaria magellanica Laskowski, Jeżewski & Zdzitowiecki, 2013. This clade is phylogenetically distinctive such that it has the potential to be recognised as a new opecoelid subfamily, but further investigation is required to establish the bounds for such a grouping and to determine the morphological and/or life-history patterns reflected by the phylogeny. Finally, we propose C. interruptus (Manter 1954) n. comb. for a species previously recognised in Plagioporus Stafford, 1904 and known only from Pseudolabrus miles (Schneider & Forster), a labrid endemic to New Zealand.

The Opecoelidae Ozaki, 1925, the largest trematode family, currently lacks an adequate subfamilial organisation. In particular, recent analyses have shown that the sequenced representatives of the Opistholebetinae Fukui, 1929 are nested among taxa currently recognised in the Plagioporinae Manter, 1947, which itself is polyphyletic. The concept of the Opistholebetinae persists because its 25 or so species are united by a distinctive morphology and a narrow host range; species are known only from tetraodontiform fishes, specifically of the Tetraodontidae and Diodontidae, and possess a muscular post-oral ring, unusual pigmented granules throughout the body and a ventral sucker positioned more posteriorly than is typical for other opecoelids. Here we report on Magnaosimum brooksae n. g., n. sp. from a tetraodontiform, Tripodichthys angustifrons (Hollard) (Triacanthidae), collected in Moreton Bay, Australia. The new species has a longer forebody than hindbody, but lacks a post-oral ring and pigmented granules. It resolves to the plagioporine clade containing the Opistholebetinae, but does not form a monophyletic grouping with those taxa. We propose to expand the concept of the Opistholebetinae to include Magnaosimum, as well as Gaevskajatrema Gibson & Bray, 1982, Macvicaria Gibson & Bray, 1982, Pachycreadium Manter, 1954, Peracreadium Nicoll, 1909, Pinguitrema Siddiqi & Cable, 1960, Propycnadenoides Fishcthal & Kuntz, 1964, Pseudopycnadena Saad-Fares & Maillard, 1986, Pycnadena Linton, 1911 and Pycnadenoides Yamaguti, 1938.

Combined morphological and molecular analyses are used to characterise two new species of Haplorchoides Chen, 1949 (Digenea: Heterophyidae) from an Australian siluriform fish. Haplorchoides maiwariensis n. sp. and H. daguilarensis n. sp. are described from the intestine of the Blue salmon catfish, Neoarius graeffei (Kner & Steindachner) (Siluriformes: Ariidae) from tidal reaches of the Brisbane River and from a freshwater creek off Lake Wivenhoe, Kipper Creek, Australia. The two new species most obviously differ from all previously described species of Haplorchoides in possessing clearly and reliably tripartite seminal vesicles. The two new species differ in the size and distribution of vitelline follicles, the size of the pigment granules and the form of the ventral sucker. Previously described species of Haplorchoides have been reported from Africa and Asia, principally from bagrid, schilbeid, silurid and sisorid catfishes; these are the first species reported from an ariid catfish. Complete ITS2 and partial 28S ribosomal DNA data were generated for both new species. The two species differ from each other by eight base pairs in the ITS2 region, and by 13 bp for the 28S region. The 28S rDNA sequence of H. daguilarensis agrees with a previously reported sequence from an unidentified species of Haplorchoides collected from N. graeffei in Lake Wivenhoe, Australia; we identify this previous report as relating to H. daguilarensis.

Despite morphological and ecological inconsistencies among species, all plagioporine opecoelids with a pedunculate ventral sucker are currently considered to belong in the genus Podocotyloides Yamaguti, 1934. We revise the genus based on combined morphological and phylogenetic analyses of novel material collected from haemulid fishes in Queensland waters that we interpret to represent species congeneric with the type-species, Pod. petalophallus Yamaguti, 1934, also known from a haemulid, off Japan. Our phylogenetic analysis demonstrates polyphyly of Podocotyloides; prompts us to resurrect Pedunculacetabulum Yamaguti, 1934; and suggests that Pod. brevis Andres & Overstreet, 2013, from a deep-sea congrid in the Caribbean, and Pod. parupenei (Manter, 1963) Pritchard, 1966 and Pod. stenometra Pritchard, 1966, from mullids and chaetodontids, respectively, on the Great Barrier Reef, may each represent a distinct genus awaiting recognition. Our revised concept of Podocotyloides requires a pedunculate ventral sucker, but also a uterine sphincter prior to the genital atrium, a petalloid cirrus appendage, restriction of the vitelline follicles to the hindbody, and for the excretory vesicle to reach to the level of the ventral sucker. Of about 20 nominal species, we recognise just three in Podocotyloides (sensu stricto): Pod. petalophallus, Pod. gracilis (Yamaguti, 1952) Pritchard, 1966 and Pod. magnatestes Aleshkina & Gaevskaya, 1985. We provide new records for Pod. gracilis, and propose two new species of Podocotyloides, Pod. australis n. sp. and Pod. brevivesiculatus n. sp., and one new Pedunculacetabulum species, Ped. inopinipugnus n. sp., all from haemulids. Podocotyloides australis is morphologically indistinguishable from Pod. gracilis, and exploits the same definitive host, but is genetically and biogeographically distinct. It is thus a cryptic species, the first such opecoelid to be formally named.

A survey of tapeworms of galeomorph sharks from Moreton Bay (Queensland, Australia) identified a complex of species of Paraorygmatobothrium Ruhnke, 1994 infecting 11 carcharhiniform and two orectolobiform species. Combined morphological and multi-locus molecular analyses (based on the 28S nuclear ribosomal RNA and partial mitochondrial NADH dehydrogenase subunit 1 genes) revealed the presence of 12 species of Paraorygmatobothrium; four species (Paraorygmatobothrium christopheri n. sp., P. harti n. sp., P. sinclairtaylori n. sp. and P. ullmanni n. sp.) are considered to be new to science and are formally described, four represent known species, and four lack sufficient morphological data to allow definitive identification. In contrast to previous records for the genus, four of the species found in this study exhibited low host specificity [P. orectolobi (Butler, 1987) Ruhnke, 2011, P. sinclairtaylori, P. ullmanni and Paraorygmatobothrium sp. 3], three stenoxenic species were each found in two closely-related sharks (P. orectolobi, P. ullmanni and Paraorygmatobothrium sp. 3) and one euryxenic species was found in five species from two shark families (P. sinclairtaylori). One species was found to exhibit mild morphologically plasticity (P. orectolobi), with size range being associated with different shark species. Conversely, collections of almost morphologically indistinguishable specimens from single shark species were found to represent multiple species of Paraorygmatobothrium. The findings of this study indicate that the description of species of this genus on the basis of morphological data alone is problematic and that the inclusion of multi-locus molecular data is essential for future work on Paraorygmatobothrium. Host specificity, morphology and phylogenetic relatedness of species of Paraorygmatobothrium are explored.

Combined morphological and molecular analyses are employed to characterise three species of Tergestia Stossich, 1899 (Digenea: Fellodistomidae) from fishes of Moreton Bay, Queensland, Australia. Tergestia clonacantha Manter, 1963 is reported here for the first time from the halfbeak (Beloniformes: Hemiramphidae) species Arrhamphus sclerolepis krefftii (Steindachner), Hyporhamphus australis (Steindachner), H. quoyi (Valenciennes) and H. regularis ardelio (Whitley). Two new species, both infecting trevally (Perciformes: Carangidae) species, are described: T. maryae n. sp. from Alepes apercna Grant and T. henryi n. sp. from Pantolabus radiatus (MacLeay). Complete ITS2 and partial 28S ribosomal DNA data were generated for each of the new taxa. The three species differ from each other by 47-58 base pairs (bp) in the ITS2 rDNA region. Phylogenetic analysis of 28S rDNA supports Tergestia as a reliable generic concept, with our analyses showing that some species of the genus form a well-supported clade to the exclusion of all other fellodistomids for which sequence data are available.

The aporocotylid fauna of the mottled spinefoot, Siganus fuscescens (Houttuyn), from Moreton Bay, Queensland, Australia, was characterised using a combined morphological and molecular approach. Four aporocotylid species were identified, three belonging to the genus Ankistromeces Nolan & Cribb, 2006 and one to Cardicola Short, 1953. Specimens of Cardicola matched an undescribed species from the same host and locality; this species is described as Cardicola mogilae n. sp. Phylogenetic analyses of ITS2 and 28S data showed that C. mogilae n. sp. forms a strongly supported clade with other Cardicola species from siganid fishes. We record Ankistromeces olsoni Nolan & Cribb, 2006 in Moreton Bay for the first time, redescribe A. dunwichensis Nolan & Cribb, 2006 on the basis of new specimens and sequence data and re-report Ankistromeces sp. X from Moreton Bay based on molecular data. We review the status of the ten putative species of aporocotylids reported from siganids. Small variation in ITS2 rDNA sequences, in association with different geographic localities, was previously used to separate Cardicola lafii Nolan & Cribb, 2006 from C. parilus Nolan & Cribb, 2006, C. bartolii Nolan & Cribb, 2006 from C. watsonensis Nolan & Cribb, 2006, C. tantabiddii Nolan & Cribb, 2006 from Cardicola sp. 2, Ankistromeces sp. Y from A. olsoni and Ankistromeces sp. X from Ankistromeces sp. Z. These five combinations are reinterpreted as each representing a single species; Cardicola lafii is recognised as the senior synonym of C. parilus and C. bartolii as the senior synonym of C. watsonensis. This study thus suggests that six, rather than ten, species should be recognised as infecting S. fuscescens. This richness remains greater than is known for any other fish species and siganids are, so far, unique among fishes in harbouring two strongly radiated lineages of aporocotylids.

Three species of Opisthomonorcheides Parukhin, 1966 are reported for the first time from Indonesian waters: O. pampi (Wang, 1982) Liu, Peng, Gao, Fu, Wu, Lu, Gao & Xiao, 2010 and O. ovacutus (Mamaev, 1970) Machida, 2011 from Parastromateus niger (Bloch), and O. decapteri Parukhin, 1966 from Atule mate (Cuvier). Both O. pampi and O. ovacutus can now be considered widespread in the Indo-Pacific region, with earlier records of these species being from Fujian Province, China and Penang, Malaysia, respectively. We redescribe O. decapteri from one of its original hosts, Atule mate, off New Caledonia, and report this species from Jakarta Bay, Indonesia, extending its range throughout the Indian Ocean into the south-western Pacific. All three species possess a genital atrium that is long, sometimes very long, and a genital pore that is located in the forebody. This validates the interpretation that the original description was erroneous in reporting the genital pore in the hindbody, well posterior to the ventral sucker. These observations verify the synonymy of Retractomonorchis Madhavi, 1977 with Opisthomonorcheides. A major discrepancy between the species of Opisthomonorcheides is that some are described with the uterus entering the terminal organ laterally and some with it entering terminally; this feature needs further analysis. Based on the length of the genital atrium and the posterior extent of the vitellarium, the 27 species of Opisthomonorcheides considered valid can be divided into four groups. Among the 53 host records analysed, the families Carangidae (53% of records), Stromateidae (17%) and Serranidae (5.7%) are the most common; the reports are overwhelmingly from members of the Perciformes (91%), with further records in the Clupeiformes (5.7%), Gadiformes (1.9%) and Pleuronectiformes (1.9%). Two fish genera (Parastromateus Bleeker and Pampus Bonaparte) dominate the recorded hosts, with the black pomfret Parastromateus niger harbouring six species, the silver pomfret Pampus argenteus (Euphrasen) harbouring six, and the Chinese silver pomfret P. chinensis (Euphrasen) two. A host-parasite checklist is presented. We discuss the host-specificity of members of the genus, questioning some records such as that of O. decapteri in a deep-sea macrourid. We also comment on the morphological similarity, but phylogenetic distance, between the various Pomfret species, advancing the possibility that a series of host misidentifications has occurred. Sequences of the ITS2 rDNA gene generated for O. pampi and O. ovacutus are briefly discussed and molecular data are lodged in the GenBank database.

Examination of three species of batfishes (Teleostei: Epphippidae) from off Lizard and Heron Islands on the Great Barrier Reef led to the discovery of specimens of the trematode genus Paradiscogaster Yamaguti, 1934 (Digenea: Faustulidae). Morphological analysis demonstrated that the new specimens represented four morphotypes which we interpret to be new species: Paradiscogaster martini n. sp., P. vichovae n. sp. and P. brayi n. sp. from Platax orbicularis (Forsskål) and P. pinnatus (Linnaeus) off Lizard Island, and P. nitschkei n. sp. from P. teira (Forsskål) off Heron Island. Published material was re-examined and the specimens identified as P. chaetodontis okinawensis Yamaguti, 1971 from P. pinnatus from Okinawa, Japan, actually represent the new species P. brayi n. sp., demonstrating that some species of Paradiscogaster have wide geographical distributions. ITS2 rDNA data for the four morphotypes differ by 4-39 base pairs confirming the delineation of the four species proposed. A feature of this study is the recognition of Platax spp. as an important host group for Paradiscogaster, with the new species placing them as the second richest host group for these parasites after the Chaetodontidae.

A new opecoelid trematode is reported from fishes of the Lethrinidae, Lutjanidae and Nemipteridae off Lizard Island on the northern Great Barrier Reef, Australia. The new species keys to Neolebouria Gibson, 1976 and shows strong similarity to several species of that genus, but is not consistent with the type-species, N. georgiensis Gibson, 1976, or others known from temperate/polar and/or deep-sea fishes. The new species is also phylogenetically distant from N. lanceolata (Price, 1934) Reimer, 1987, the only representative of the genus for which molecular data are available. A new genus, Trilobovarium n. g., is proposed for the new species, T. parvvatis n. sp. Eight morphologically similar species, previously recognised as belonging to Neolebouria, from shallow-water, mostly tropical/subtropical fishes, are transferred to Trilobovarium: T. diacopae (Nagaty & Abdel Aal, 1962) n. comb.; T. ira (Yamaguti, 1940) n. comb.; T. khalili (Ramadan, 1983) n. comb.; T. krusadaiense (Gupta, 1956) n. comb.; T. lineatum (Aken'Ova & Cribb, 2001) n. comb.; T. moretonense (Aken'Ova & Cribb, 2001) n. comb.; T. palauense (Machida, 2014) n. comb.; and T. truncatum (Linton, 1940) n. comb. Paramanteriella Li, Qiu & Zhang, 1988 is resurrected for five species of Neolebouria with a post-bifurcal genital pore: P. cantherini Li, Qiu & Zhang, 1988; P. capoori (Jaiswal, Upadhyay, Malhotra, Dronen & Malhotra, 2014) n. comb.; P. confusa (Overstreet, 1969) n. comb.; P. leiperi (Gupta, 1956) n. comb.; and P. pallenisca (Shipley & Hornell, 1905) n. comb. Neolebouria georgenascimentoi Bray, 2002, a species with an exceptionally long cirrus-sac, is transferred to Bentholebouria Andres, Pulis & Overstreet, 2004 as B. georgenascimentoi (Bray, 2002) n. comb., and N. maorum (Allison, 1966) Gibson 1976, an unusual species known from cephalopods, is designated a species incertae sedis. Eleven species are retained in a revised concept of Neolebouria.

Two new species of Cardicola Short, 1953 are described from the milkfish, Chanos chanos Forsskål (Gonorynchiformes: Chanidae), obtained from off Lizard Island on the northern Great Barrier Reef (GBR) and North Stradbroke Island in southeast Queensland. These are the first known blood flukes from this order of fishes. Cardicola suni n. sp. differs from all other Cardicola spp. by a combination of a large ovoid oral sucker surrounding a subterminal mouth, recurved tegumental spines up to 16 μm long, anterior caeca occupying 25.1-31.3% (28.7%) of total body length and a mostly-intercaecal ovary. Cardicola jiigurru n. sp. differs from C. suni n. sp. and all other species of Cardicola by a combination of a narrowly lanceolate body, weakly-muscularised and poorly-demarcated oral sucker, minute tegumental spines <1 µm in length, and anterior caeca occupying 15.9-22.0% (19.4%) of total body length, an almost entirely post-caecal ovary and the male genital pore terminal on a dorsolateral protuberance. A third species, closely resembling C. suni n. sp., was also discovered off Wangetti Beach, north Queensland, but is not described due to lack of material. Molecular phylogenetic analysis, based on both ITS2 and partial 28S rDNA regions, shows that these three species form a clade nested within that formed by existing species of Cardicola.

A new species of microphallid, Longiductotrema tethepae n. sp., is reported from a muraenid eel Gymnothorax pseudothyrsoideus (Bleeker) on the northern Great Barrier Reef. The new species is described based on adults from Gy. pseudothyrsoideus and metacercariae from a grapsid crab, Grapsus albolineatus Latreille in Milbert, collected from off Lizard Island, Queensland, Australia. The new species is assigned to Longiductotrema Deblock & Heard, 1969 based on morphological characters (presence of a cirrus-sac; a long metraterm, intensively ensheathed by gland-cells; an entirely postcaecal uterus; vitellarium composed of two lateral clusters each of about ten follicles, situated in the testicular and post-testicular areas). Longiductotrema tethepae n. sp. is the third species assigned to the genus, differing from its congeners in having a distinctly larger body dimensions, a smaller pharynx in relation to oral sucker, the anterior limits of the vitelline fields at the level of the testes (vs at the level of the ovary) and in its parasitism of a muraenid fish (vs birds). Additionally, the new species differs from L. floridense Deblock & Heard, 1969 in having a shorter metraterm and from L. scandolensis Deblock & Bartoli, 1988 in having a less elongate forebody in relation to body length, shorter caeca and prepharynx, and slightly larger eggs. Phylogenetic analyses, based on partial 28S rRNA gene sequences, showed that the present species is sister to all other microphallids for which sequence data are available. This is the fourth report of a microphallid from a marine eel, the first from the Muraenidae Rafinesque and the first from a marine fish in the Indo-west Pacific. A summary of all species of the Microphallidae parasitising fish is provided.

Four transversotrematid trematodes are reported from commercial teleost species in Australian waters. Transversotrema hunterae n. sp. is described from three species of Sillago Cuvier (Sillaginidae) from Moreton Bay, south-east Queensland. Molecular characterisation using ITS2 rDNA confirmed this stenoxenic specificity of Transversotrema hunterae n. sp., with identical sequence data from Sillago maculata Quoy & Gaimard, S. analis Whitley and S. ciliata Cuvier. Phylogenetic analysis, based on 28S rDNA data, demonstrates that T. hunterae n. sp. belongs to the 'Transversotrema licinum clade' and is most closely related to Transversotrema licinum Manter, 1970 and T. polynesiae Cribb, Adlard, Bray, Sasal & Cutmore, 2014, with the three species forming a well-supported clade in all analyses. We extend the known host and geographical ranges of three previously described Transversotrema species, T. licinum, T. elegans Hunter, Ingram, Adlard, Bray & Cribb, 2010 and T. espanola Hunter & Cribb, 2012. The new records represent significant range extensions for the three species and permit further examination of the patterns of biogeographical distribution in Australian waters. Host-specificity of Transversotrema species is examined, and the degree to which morphological analysis can inform taxonomic studies of this group is discussed.

Using novel molecular and morphological data we elucidated the life-cycle of Gorgocephalus yaaji Bray & Cribb, 2005 from off Lizard Island, on the northern Great Barrier Reef, Australia. ITS2 rDNA sequences generated for larval trematodes from the infected snail species Echinolittorina austrotrochoides Reid (Littorinidae) were identical to those from adult G. yaaji from the fish Kyphosus cinerascens (Forsskål) (Kyphosidae). Cercariae develop in rediae in E. austrotrochoides, emerge from the snail, encyst on algae as metacercariae, and are inferred to then be consumed by the herbivorous definitive fish host, K. cinerascens. In addition, we generated the first ITS2 rDNA sequences for a gorgocephalid previously reported from the littorind gastropod Austrolittorina unifasciata Gray. Although infections previously reported from A. unifasciata were the first larval gorgocephalids characterised, this study is the first to connect an intramolluscan infection to a sexual adult. In light of the new life-cycle information, a review of mollusc associations for the digenean superfamily Lepocreadioidea was performed, highlighting gaps in the knowledge and revealing patterns of host-parasite association. We find that distinct patterns of first intermediate host association are discernible for three lepocreadioid lineages: the Aephnidiogenidae Yamaguti, 1934, Gorgocephalidae Manter, 1966, and the Lepocreadiidae Odhner, 1905. However, the evolutionary origin for these patterns of host association remains unclear.

To date, morphological analysis has been the cornerstone to trematode systematics. However, since the late-1980s we have seen an increased integration of genetic data to overcome problems encountered when morphological data are considered in isolation. Here, we provide advice regarding the 'best molecular practice' for trematode taxonomy and systematic studies, in an attempt to help unify the field and provide a solid foundation to underpin future work. Emphasis is placed on defining the study goals and recommendations are made regarding sample preservation, extraction methods, and the submission of molecular vouchers. We advocate generating sequence data from all parasite species/host species/geographic location combinations and stress the importance of selecting two independently evolving loci (one ribosomal and one mitochondrial marker). We recommend that loci should be chosen to provide genetic variation suitable to address the question at hand and for which sufficient 'useful' comparative sequence data already exist. Quality control of the molecular data via using proof-reading Taq polymerase, sequencing PCR amplicons using both forward and reverse primers, ensuring that a minimum of 85% overlap exists when constructing consensus sequences, and checking electropherograms by eye is stressed. We advise that all genetic results are best interpreted using a holistic biological approach, which considers morphology, host identity, collection locality, and ecology. Finally, we consider what advances next-generation sequencing holds for trematode taxonomy and systematics.

The Indo-west Pacific is a marine bioregion stretching from the east coast of Africa to Hawaii, French Polynesia and Easter Island. An assessment of the literature from the region found reports of 2,582 trematode species infecting 1,485 fish species. Reports are concentrated in larger fishes, undoubtedly reflecting the tendency for larger hosts to be infected by more species of parasites as well as a collecting bias. Many hundreds of fish species, including many from families known to be rich in trematodes, have yet to be reported as hosts. Despite some areas (the Great Barrier Reef, Hawaii and the waters off China, India and Japan) receiving sustained attention, none can be considered to be comprehensively known. Several regions, most importantly in East Africa, French Polynesia and the Coral Triangle, are especially poorly known. The fauna of the Indo-west Pacific has been reported so unevenly that we consider it impossible to predict the true trematode richness for the region. We conclude that the greatest gap in our understanding is of the geographical distribution of species in the Indo-west Pacific. This is highlighted by the fact that 87% of trematodes in the region have been reported no more than five times. The reliable recognition of species is a major problem in this field; molecular approaches offer prospects for resolution of species identification but have been little adopted to date.

Species of the faustulid genus Antorchis Linton, 1911 of the tropical Indo-West Pacific are reviewed. We recognise five species in the region, including a novel form. Antorchis nasonis n. sp. is described from Naso annulatus (Quoy & Gaimard) and N. tonganus (Valenciennes) on the southern Great Barrier Reef (GBR). We interpret specimens reported from Naso hexacanthus (Bleeker) from Japan as the same species. This species appears to be the only faustulid known from acanthurid fishes and differs from all other species in the genus in having the prominent dorsal genital invagination close to the posterior end of the body. In addition, new host and locality records are reported for two described species of Antorchis, A. pomacanthi (Hafeezullah & Siddiqi, 1970) and A. tsushimaensis (Machida, 1971). The wide distribution of A. pomacanthi was further demonstrated by the generation of identical ITS2 rDNA sequences for specimens from Ningaloo Reef off Western Australia, off Lizard and Heron Islands (GBR) and off New Caledonia, localities separated by up to 5,300 km. The host-specificity of the genus is considered.

Combined morphological and molecular analysis shows that a species of Bivesicula Yamaguti, 1934 from four species of Apogonidae Günther [Nectamia fusca (Quoy & Gaimard), Ostorhinchus angustatus (Smith & Radcliffe), O. cookii (Macleay) and Taeniamia fucata (Cantor)] on the Great Barrier Reef is morphologically similar to, but clearly distinct from B. unexpecta Cribb, Bray & Barker, 1994 which infects a sympatric pomacentrid, Acanthochromis polyacanthus (Bleeker). Bivesicula neglecta n. sp. is proposed for the form from apogonids. Novel ITS2 rDNA sequences generated for the two species differ at just one consistent base position, implying that the two species are closely related. The combination of their close relationship, high but distinct specificity and co-occurrence suggests that speciation was driven by a recent host switching event enabled by similar dietary ecomorphology.

During helminthological examinations of teleost fishes of Ningaloo Reef, Western Australia, a new species of the enigmatic genus Plectognathotrema Layman, 1930 was discovered infecting the pot-bellied leatherjacket Pseudomonacanthus peroni (Hollard). The new species, Plectognathotrema kamegaii n. sp., is formally described, and the status of its four congeners is reviewed. Plectognathotrema hydrolagi Olson, Hanson & Pratt, 1970 is not recognised within the genus, as it differs greatly from its congeners in the form and arrangement of the vitellarium, testes and uterus, and in that it was described from a holocephalan. Plectognathotrema cephalopore Layman, 1930 and P. tsushimaense Kamegai, 1970 are morphologically similar, were described from the same host species and from close geographical localities and are considered synonymous. The new taxon is most similar to P. cephalopore, but differs from it in being much smaller and possessing a distinctly larger oral sucker relative to its body size. The generation of novel partial 28S ribosomal DNA sequences allowed a phylogenetic assessment of the genus and demonstrated that Plectognathotrema clearly belongs in the Zoogonidae Odhner, 1902, rather than in the Fellodistomidae Nicoll, 1909, where it is currently assigned. With the inclusion of Plectognathotrema in the Zoogonidae, there are now three zoogonid genera for which the species are restricted to monacanthid teleosts, i.e. Cephaloporus Yamaguti, 1934, Plectognathotrema and Yamagutiplectognathotrema Parukhin, 1977. Species of these genera share pronounced morphological and ecological affinities and a previously synonymised subfamily, the Cephaloporinae Yamaguti, 1934, is resurrected for them. The host specificity of these trematodes is commented upon.

Five monorchiid species are reported from Diagramma labiosum Macleay (Perciformes: Haemulidae) collected from Heron Island on the southern Great Barrier Reef (GBR): two described species, Helicometroides longicollis Yamaguti, 1934 and Diplomonorchis kureh Machida, 2005 and three new species, including one new genus, Asymmetrostoma heronensis n. g., n. sp., Lasiotocus arrhichostoma n. sp. and Proctotrema addisoni n. sp. Helicometroides longicollis and D. kureh were previously reported from the closely related species Diagramma pictum (Thunberg) from Japan. Two further monorchiid species known from D. pictum, Genolopa plectorhynchi (Yamaguti, 1934) and Paraproctotrema fusiforme Yamaguti, 1934, appear to be absent from the southern Great Barrier Reef. Previous reports of two other monorchiids from D. labiosum from the GBR, Paramonorcheides pseudocaranxi Dove & Cribb, 1998 and Helicometroides vitellosus (Durio & Manter, 1968), are shown to have been made in error. The high richness of monorchiids and other trematode families in D. labiosum is consistent with that seen in other haemulids elsewhere.

A new species of digenean, Pseudobacciger cheneyae n. sp., is described from the intestines of Weber's chromis (Chromis weberi Fowler & Bean) from off Lizard Island, Great Barrier Reef, Australia. This species differs from the three described species of Pseudobacciger Nahhas & Cable, 1964 [P. cablei Madhavi, 1975, P. harengulae Yamaguti, 1938 and P. manteri Nahhas & Cable, 1964] in combinations of the size of the suckers and the length of the caeca. The host of the present species is a perciform (Family Pomacentridae) which contrasts with previous records of the genus which are almost exclusively from clupeiform fishes. The genus Pseudobacciger is presently recognised within the family Faustulidae (Poche, 1926) but phylogenetic analyses of 28S and ITS2 rDNA show that the new species bears no relationship to species of four other faustulid genera (Antorchis Linton, 1911, Bacciger Nicoll, 1924, Paradiscogaster Yamaguti, 1934 and Trigonocryptus Martin, 1958) but that instead it is nested within the Gymnophalloidea (Odhner, 1905) as sister to the Tandanicolidae (Johnston, 1927). This result suggests that the Faustulidae is polyphyletic.

A sexual adult trematode that is considered to be conspecific with the distinctive larval trematode Cercaria praecox Walker, 1971 is reported from the kyphosid fish Scorpis lineolata Kner in Moreton Bay, Queensland, Australia. The sexual adult is consistent with the cercarial body of Cercaria praecox in having a single caecum with an asymmetrical appendix, symmetrical testes immediately posterior to the ventral sucker, and the ovary and vitellarium both well posterior to the testes. This combination of characters is distinct within the Fellodistomidae Nicoll, 1909 and requires the proposal of a new genus, Oceroma n. g. Analysis of 28S rDNA sequences demonstrates that this species forms a clade with Coomera Dove & Cribb, 1995 within the Fellodistomidae. The life-cycle of the species is predicted to require two hosts and to involve the direct ingestion of the cercaria.

A new genus and species of tetraphyllidean cestode, Caulopatera pagei n. g., n. sp., is described from the grey carpetshark Chiloscyllium punctatum Müller & Henle in Moreton Bay, Australia. The new genus is placed in the Phyllobothriidae, subfamily Phyllobothriinae. Caulopatera n. g. is distinct from all other phyllobothriine genera in having stalked, circular, non-loculate bothridia that lack an apical sucker, testes that are restricted to the region anterior to the cirrus-sac and circum-medullary vitelline follicles. The new genus most closely resembles Carpobothrium Shipley & Hornell, 1906, with which it shares non-loculate, stalked, unhooked bothridia without an accessory sucker and testes that are entirely anterior to the cirrus-sac, but differs from it in that it lacks a slit-like opening in each bothridium and flaps surrounding the opening. The possession of bothridial stalks is consistent with two cestode orders, the Tetraphyllidea and the Rhinebothriidea. The morphology of the bothridial stalks is consistent with other tetraphyllidean genera, in that Caulopatera possesses triangular bothridial stalks surrounding the back of the bothridia, indicating that it belongs in the Tetraphyllidea senso stricto, rather than in the recently recognised Rhinebothriidea.

Paraorygmatobothrium taylori n. sp. (Tetraphyllidea: Phyllobothriidae) is described from the Australian weasel shark Hemigaleus australiensis White, Last & Compagno in Moreton Bay, off Queensland, Australia. The new species differs from 10 of the 11 described species of Paraorygmatobothrium Ruhnke, 1994 by the possession of prominent, semicircular bothridial muscle bands. From P. barberi Ruhnke, 1994, with which it shares the bothridial muscle bands, it differs in the possession of a cephalic peduncle and vitelline follicles that extend almost to the mid-line of the proglottis and are reduced, rather than completely interrupted, at the level of the ovary. P. janineae Ruhnke, Healy & Shapero, 2006 is recorded from its type-host but in a new locality, Moreton Bay, off Queensland, Australia. P. taylori is the third species of the genus recorded from the Hemigaleidae in Australian waters. Three of the eight known hemigaleid species are now recorded to harbour this genus, and three different species are now known from the two hemigaleids found in Australian waters.