Discovering high species diversity of Ophiotaenia tapeworms (Cestoda: Proteocephalidae) of watersnakes (Colubridae) in North America.

Tapeworms of the genus Ophiotaenia La Rue, 1911 parasitize herptiles (= amphibians and 'reptiles') throughout the world, with about 100 species recognised as valid. In the present work, the North American species found in watersnakes (Colubridae) are reviewed. An examination of the holotype of Ophiotaenia perspicua La Rue, 1911, the type species of the genus, and other specimens from Nerodia rhombifer (Hallowell) revealed that two species were used for the species description. The 'true' O. perspicua has a small scolex and small, round suckers. This species is redescribed based on new material from Oklahoma, USA. The other species from N. rhombifer, Ophiotaenia laruei n. sp., has a larger scolex and larger, almost triangular suckers. Examination of the types of O. variabilis (Brooks, 1978) from N. rhombifer and N. cyclopion (Duméril, Bibron et Duméril) from Louisiana, USA has revealed that it is a mixture of two or more species. Because of poor quality of these specimens, it is not possible to adequately characterise O. variabilis, which is considered a species inquirenda. In addition, two new species are described from Nerodia fasciata confluens (Blanchard). Ophiotaenia currani n. sp. from Mississippi, USA is characterised by elongate, narrow proglottids, few testes, and a relatively long cirrus sac. Ophiotaenia tkachi n. sp. from Louisiana, USA is characterised by relatively short and wide proglottids, more testes, and an unusual terminal part of the vagina with folds. Morphologically similar tapeworms of N. fasciata confluens, N. erythrogaster (Förster), N. sipedon (Linnaeus), and Agkistrodon piscivorus (Lacépède) (Viperidae) from Arkansas and Oklahoma, USA, which are genetically nearly identical, are considered to be conspecific with O. tkachi n. sp. The present data suggest a high, previously undescribed species diversity of proteocephalid tapeworms in watersnakes in North America, and generally strict host specificity of these tapeworms.

Novel insights into the genetics, morphology, distribution and hosts of the global fish parasitic digenean Proctoeces maculatus (Looss, 1901) (Digenea: Fellodistomidae).

Larval stages of the widely distributed digenean species Proctoeces maculatus (Looss, 1901) were reported 40 years ago from South Africa in the common octopus, Octopus vulgaris Cuvier (Octopodidae). However, the absence of adult specimens and molecular data from this region has hindered a comprehensive understanding of its distribution. In this study, we collected three species of intertidal and near-shore marine fishes [Clinus superciliosus (L.) (Clinidae), Diplodus capensis (Smith) (Sparidae) and Sparodon durbanensis (Castelnau) (Sparidae)] along the South African coast and discovered adult specimens of P. maculatus at five localities. By employing a combination of morphological and molecular techniques, including 28S rDNA, 18S rDNA and COI mtDNA analyses, the first report of adult P. maculatus from South Africa is presented. The findings encompass a comprehensive morphological description and molecular data, illuminating the true distribution of this species in the region.

Molecular characterisation of three species of Coitocaecum (Digenea: Opecoelidae) infecting Clinus superciliosus (Clinidae) in South Africa, with description of Coitocaecum brayi sp. n.

The genus Coitocaecum Nicoll, 1915 is part of the most speciose digenean family, the Opecoelidae Ozaki, 1925, which is found globally in both freshwater and marine fishes. Fifteen opecoelid species have been reported from marine fishes in South Africa, yet only one species of Coitocaecum has been described from this region: Coitocaecum capense Bray, 1987. During an explorative study of the digeneans of the endemic, intertidal fish Clinus superciliosus (Linnaeus) from the Saldanha Bay area, Cape Town harbour, Hermanus, the Tsitsikamma section of the Garden Route National Park and Chintsa East in South Africa, a total of three distinct species of Coitocaecum were identified based on morphological and molecular (28S rDNA, ITS1-5.8S-ITS2 rDNA and COI mtDNA) data: the previously mentioned C. capense, Coitocaecum brayi sp. n. and a third, unnamed species. We provide the first molecular characterisation of species of Coitocaecum from South Africa, accompanied by detailed morphological descriptions. This study illustrates the importance of an integrated taxonomic approach, especially when studying species with similar morphology. These findings further emphasise the lack of information on the true diversity and molecular data for trematodes of marine fishes in South Africa, creating a great capacity for future explorative taxonomic studies and highlighting the use of intertidal areas for conducting such research.

A global survey of tapeworms (Cestoda: Proteocephalidae) of 'true' frogs (Amphibia: Ranidae), including a tabulated list of all proteocephalids parasitising amphibians.

Proteocephalid tapeworms of frogs of the family Ranidae ('true' frogs) are reviewed with emphasis on their species diversity, host specificity and geographical distribution. New molecular data (nuclear lsrDNA and mitochondrial COI sequences) are presented for tapeworms of four species of ranid frogs in North America, including the poorly known Ophiotaenia saphena Osler, 1931 of Rana clamitans Latreille and R. catesbeiana (Shaw), which is redescribed using new material from Arkansas, USA. Tapeworms of R. sphenocephala (Cope) and R. pipiens Schreber, the latter previously identified as O. saphena, represent another, putative new species, but are not formally described due to insufficient available material. Proteocephalus papuensis Bursey, Goldberg et Kraus, 2008 from Sylvirana supragrisea (Menzies) is transferred to Ophiotaenia La Rue, 1911 as a new combination. After a critical review of the literature, only nine nominal species of Ophiotaenia are recognised as valid, which is in contrast to the large number of ranid frogs (> 440 spp.). The reasons for this striking disparity are briefly discussed, and a key based on morphology is presented for the identification of all species of Ophiotaenia from the Ranidae. Molecular data are available for only two taxa from North America that form a monophyletic group. The relationships among tapeworms of ranid frogs occurring in other zoogeographical regions are not yet known. The taxonomic status of Batrachotaenia Rudin, 1917, which was erected to accommodate proteocephalids from amphibians, is also discussed. To facilitate future studies, a tabulated summary of all 32 species of proteocephalids belonging to three genera reported from amphibians (frogs and salamanders) is presented, with information on their hosts, distribution, and taxonomically important characters, including key measurements.

Prey-mimetism in cercariae of Apatemon (Digenea, Strigeidae) in freshwater in northern latitudes.

Cercariae, the free-living larval stages of trematodes, have adopted an amazing variety of transmission strategies. One of them is prey-mimetism, i.e. cercariae mimicking prey to attract motile hosts to be eaten. In a period between 2002 and 2019, we examined small planorbid snails, Bathyomphalus contortus, Gyraulus parvus and Planorbis planorbis from lakes in Finland and Iceland and from the Curonian Lagoon in Lithuania. Cercariae with conspicuously enlarged tails and unusual swimming behaviour, likely mimicking invertebrate prey, were detected and studied by the use of morphological and molecular (cox1, ITS1-5.8S-ITS2 and 28S rDNA) methods. Cercariae of two species belonging to the genus Apatemon (Strigeidae) were recognised. We consider Apatemon sp. 5 ex P. planorbis from the Curonian Lagoon identical to Cercaria globocaudata U. Szidat, 1940. Cercariae ex G. parvus from Iceland and ex B. contortus from Finland were conspecific, and we named them Apatemon sp. 6; these cercariae could not be associated with any known species. For the first time, we verified that cercariae of the Bulbocauda group belong to the genus Apatemon. We provide a mini-review on records of furcocercariae of the family Strigeidae with enlarged tails reported in freshwaters of the northern hemisphere and reveal that it is not only Apatemon but also Australapatemon and most likely Strigea which belong to the Bulbocauda group, rendering it a purely ecological assemblage. Understanding which invertebrate swimming behaviour these cercariae are mimicking will enhance our knowledge of the processes behind trematode transmission and will help to assess evolutionary pathways of host-finding strategies in trematodes.

Hemiurid Trematodes (Digenea: Hemiuridae) from Marine Fishes off the Coast of Rio de Janeiro, Brazil, with Novel Molecular Data.

Brazil is a tropical country with remarkably diverse marine habitats that harbour a rich diversity of fish. Only a small portion of this fish diversity has been investigated for parasites, and thus the diversity of their trematode parasites remains unexplored. Moreover, only 5 out of 184 known digenean trematode species of marine fish in Brazil have been genetically characterised. The Hemiuridae Looss, 1899 is the second most speciose trematode family in marine fishes from Brazil but, in many ways, it remains a neglected group. Forty-three trematode specimens from nine fish species were collected from the coastal zone off Rio de Janeiro, Brazil. Trematodes were found in the stomach of 14 specimens of 9 fish species belonging to 8 families (Carangidae, Clupeidae, Haemulidae, Muraenidae, Percophidae, Pinguipedidae, Trichiuridae, and Triglidae). Trematode specimens were studied using morphological and molecular genetic analyses. A total of eight hemiurid species from four genera, Ectenurus, Lecithochirium, Myosaccium, and Parahemiurus were identified. This paper reports on new host records for four species of hemiurids, adds a new record on the geographical distribution for one species, and provides the first DNA sequence data supplemented with the detailed description of morphology for five species. Phylogenetic analyses supported that the subfamily classifications of the Hemiuridae-based entirely on morphological characters-needs to be reconsidered, taking into account a wider range of information sources.

Digenean trematodes infecting the frigate tuna Auxis thazard (Scombriformes, Scombridae) off the Rio de Janeiro coast, Brazil, including molecular data.

Although some parasitological efforts have focused on the frigate tuna Auxis thazard (Lacepède) (Scombriformes, Scombridae) in Brazil, its digenean fauna remains poorly known. Combining morphological and molecular methods, we investigated the diversity of digenean trematodes of A. thazard collected from the coastal waters off the state of Rio de Janeiro, Brazil in 2021. Six species belonging to four families were recorded: the bucephalid Rhipidocotyle cf. angusticolle Chandler, 1941, the didymozoid Didymocystis sp. 6 sensu Louvard et al. (2022), the fellodistomid Tergestia sp., and three hemiurids, Dinurus euthynni Yamaguti, 1934, Lecithochirium floridense (Manter, 1934), and L. synodi Manter, 1931. The current study brings the total number of digenean trematode species parasitising A. thazard in Brazil up to eight, with hemiuroid trematodes being most diverse. Auxis thazard is a new host record for L. floridense, L. synodi and potentially for R. angusticolle. The geographic distribution of several species found in our study appeared to be wider than previously known. Our study is the first to apply a DNA-based approach to digenean diversity in marine fishes in Brazil and we believe that both morphological descriptions and molecular sequence data provided in our study will aid future research assessing the diversity of digenean trematodes of A. thazard and other marine fishes in Brazil.

Title: Trématodes Digènes infectant l'auxide Auxis thazard (Scombriformes, Scombridae) au large de la côte de Rio de Janeiro, Brésil, avec des données moléculaires. Abstract: Bien que certains efforts parasitologiques aient porté sur l'auxide Auxis thazard (Lacepède) (Scombriformes : Scombridae) au Brésil, la faune de ses digènes reste mal connue. En combinant des méthodes morphologiques et moléculaires, nous avons étudié la diversité des trématodes digènes d'A. thazard collectés dans les eaux côtières au large de l'État de Rio de Janeiro, Brésil en 2021. Six espèces appartenant à quatre familles ont été répertoriées : le Bucephalidae Rhipidocotyle cf. angusticolle Chandler, 1941, le Didymozoidae Didymocystis sp. 6 sensu Louvard et al. (2022), le Fellodistomidae Tergestia sp., et trois Hemiuridae, Dinurus euthynni Yamaguti, 1934, Lecithochirium floridense (Manter, 1934) et L. synodi Manter, 1931. L'étude actuelle porte le nombre total d'espèces de trématodes digènes parasitant A. thazard au Brésil à huit, les Hemiuroidea étant les plus diversifiés. Auxis thazard est un nouveau signalement d'hôte pour L. floridense, L. synodi et potentiellement R. angusticolle. La répartition géographique de plusieurs espèces trouvées dans notre étude semble être plus large que ce que nous savions auparavant. Notre étude est la première à appliquer une approche basée sur l'ADN à la diversité des digènes chez les poissons marins au Brésil et nous pensons que les descriptions morphologiques et les données de séquence moléculaire fournies dans notre étude aideront les recherches futures évaluant la diversité des trématodes digènes d'A. thazard et d'autres poissons marins du Brésil.

A NEW GENUS OF DIPLOSTOMIDS (DIGENEA: DIPLOSTOMOIDEA) FROM THE NILE CROCODILE IN SOUTH AFRICA WITH A KEY TO DIPLOSTOMID GENERA.

The Diplostomidae Poirier, 1886 is a large family of digeneans within the superfamily Diplostomoidea Poirier, 1886. Members of the family are distributed worldwide and parasitize a diversity of tetrapod definitive hosts. Notably, only 2 mature diplostomids are known from crocodilians and both are suggested to be accidental infections. In this study, we use morphological and molecular data to describe Neofibricola n. gen. from a Nile crocodile Crocodylus niloticus collected in South Africa. We provide a description of adults and metacercariae of the type species, Neofibricola smiti n. sp., and metacercariae of a likely congeneric species. We generated partial 28S and internal transcribed spacer region ribosomal deoxyribonucleic acid (DNA) and cytochrome c oxidase 1 subunit mitochondrial DNA for both species and utilized the newly generated 28S sequences to examine phylogenetic affinities of these new taxa. In addition, we provide a new key to diplostomid genera, considering the substantial systematic changes and newly erected genera since the previously published key to diplostomid genera.

Trematodes from Antarctic teleost fishes off Argentine Islands, West Antarctica: molecular and morphological data.

In 2014-2015 and 2019-2021, teleost fishes off Galindez Island (Antarctic Peninsula) were examined for trematodes. Combined morphological and molecular analyses revealed the presence of eight trematode species of four families (Hemiuridae, Lecithasteridae, Opecoelidae, Lepidapedidae) from five fish species. Only adult trematodes were found and all of them are Antarctic endemics with their congeners occurring on other continents. The hemiuroids, Elytrophalloides oatesi (Leiper & Atkinson, 1914), Genolinea bowersi (Leiper & Atkinson, 1914), and Lecithaster macrocotyle Szidat & Graefe, 1967 belong to the most common Antarctic species and together with Lepidapedon garrardi (Leiper & Atkinson, 1914) and Neolebouria georgiensis Gibson, 1976 they were recorded as the least host-specific parasites. The originally sub-Antarctic Neolepidapedon macquariensis Zdzitowiecki, 1993 is a new record for the Antarctic Peninsula and Parachaenichthys charcoti (Vaillant), is a new host record. Neolebouria terranovaensis Zdzitowiecki, Pisano & Vacchi, 1993 is considered a synonym of N. georgiensis because of identical morphology and dimensions. The currently known phylogenetic relationships within the studied families are supported, including the polyphyly of Macvicaria Gibson & Bray, 1982 with the future need to accommodate its Antarctic species in a new genus. The validity of M. georgiana (Kovaleva & Gaevskaja, 1974) and M. magellanica Laskowski, Jezewski & Zdzitowiecki, 2013 needs to be confirmed by further analyses. Genetic sequence data are still scarce from Antarctica, and more studies applying integrative taxonomic approaches and large-scale parasitological examinations of benthic invertebrates are needed to match sequences of larval stages to those of well-characterised adults and to elucidate trematode life-cycles.

Another plea for 'best practice' in molecular approaches to trematode systematics: Diplostomum sp. clade Q identified as Diplostomum baeri Dubois, 1937 in Europe.

DNA sequence data became an integral part of species characterization and identification. Still, specimens associated with a particular DNA sequence must be identified by the use of traditional morphology-based analysis and correct linking of sequence and identification must be ensured. Only a small part of DNA sequences of the genus Diplostomum (Diplostomidae) is based on adult isolates which are essential for accurate identification. In this study, we provide species identification with an aid of morphological and molecular (cox1, ITS-5.8S-ITS2 and 28S) characterization of adults of Diplostomum baeri Dubois, 1937 from naturally infected Larus canus Linnaeus in Karelia, Russia. Furthermore, we reveal that the DNA sequences of our isolates of D. baeri are identical with those of the lineage Diplostomum sp. clade Q , while other sequences labelled as the 'D. baeri' complex do not represent lineages of D. baeri. Our new material of cercariae from Radix balthica (Linnaeus) in Ireland is also linked to Diplostomum sp. clade Q. We reveal that D. baeri is widely distributed in Europe; as first intermediate hosts lymnaeid snails (Radix auricularia (Linnaeus), R. balthica) are used; metacercariae occur in eye lens of cyprinid fishes. In light of the convoluted taxonomy of D. baeri and other Diplostomum spp., we extend the recommendations of Blasco-Costa et al. (2016, Systematic Parasitology 93, 295­306) for the 'best practice' in molecular approaches to trematode systematics. The current study is another step in elucidating the species spectrum of Diplostomum based on integrative taxonomy with well-described morphology of adults linked to sequences.

Archigetes Leuckart, 1878 (Cestoda, Caryophyllidea): diversity of enigmatic fish tapeworms with monoxenic life cycles.

The caryophyllidean genus Archigetes Leuckart, 1878 is unique among all tapeworms in that its species can mature in invertebrate hosts (Oligochaeta), i.e., have a monoxenic (direct) life cycle. All five species were described as progenetic plerocercoids in oligochaetes and two of them also as adults from cypriniform fishes. Two species, A. sieboldi Leuckart, 1878 and A. iowensis Calentine, 1962, were found in North America in non-native common carp (Cyprinus carpio). A molecular study of caryophyllideans from the southern United States has revealed the occurrence of three new species in native freshwater fishes (Catostomidae, Ictiobinae): Archigetes loculotruncatus n. sp. from Ictiobus bubalus, I. niger and Carpiodes cyprinus is the largest representative of the genus and differs by a loculotruncate scolex. Archigetes megacephalus n. sp. from Ictiobus niger, I. bubalus and I. cyprinellus is characterised by a prominent, bothrioloculodiscate scolex. Archigetes vadosus n. sp. from I. bubalus is typified by a globular scolex with very shallow loculi; it differs from the closely related A. sieboldi in the shape of the body, with a distinct neck region and a scolex wider than the remaining body. Archigetes iowensis Calentine, 1962 becomes a junior synonym of Paraglaridacris limnodrili (Yamaguti, 1934). The generic diagnosis of Archigetes is amended and a key to identification of North American taxa is provided. Species of Archigetes and Paraglaridacris differ from each other most conspicuously in the structure of the ovary, which is follicular in Archigetes versus compact in Paraglaridacris.

TITLE: Archigetes Leuckart, 1878 (Cestoda, Caryophyllidea) : diversité de cestodes de poissons énigmatiques à cycle de vie monoxène. ABSTRACT: Le genre Archigetes Leuckart, 1878 (Caryophyllidea) est unique parmi les cestodes en ce sens que ses espèces peuvent atteindre la maturité chez des hôtes invertébrés (Oligochaeta), c'est-à-dire avoir un cycle de vie monoxénique (direct). Les cinq espèces ont été décrites à partir de plérocercoïdes progénétiques chez des oligochètes et deux d'entre elles aussi à partir d'adultes chez des poissons cypriniformes. Deux espèces, A. sieboldi Leuckart, 1878 et A. iowensis Calentine, 1962, ont été trouvées en Amérique du Nord chez des carpes communes (Cyprinus carpio), non indigènes. Une étude moléculaire des caryophyllidés du sud des États-Unis a révélé la présence de trois nouvelles espèces chez les poissons d'eau douce indigènes (Catostomidae, Ictiobinae). Archigetes loculotruncatus n. sp. d'Ictiobus bubalus, I. niger et Carpiodes cyprinus est le plus grand représentant du genre et est caractérisé par un scolex loculotronqué. Archigetes megacephalus n. sp. d'Ictiobus niger, I. bubalus et I. cyprinellus est caractérisé par un scolex proéminent et bothrioloculodisqué. Archigetes vadosus n. sp. d'I. bubalus est caractérisé par un scolex globulaire avec des loges très peu profondes, et diffère d'A. sieboldi, étroitement apparenté, par la forme du corps, avec une région du cou distincte et un scolex plus large que le reste du corps. Archigetes iowensis Calentine, 1962 devient un synonyme plus récent de Paraglaridacris limnodrili (Yamaguti, 1934). Le diagnostic générique d'Archigetes est modifié et une clé d'identification des taxons nord-américains est fournie. Les espèces d'Archigetes et de Paraglaridacris diffèrent de la manière la plus visible les unes des autres par la structure de l'ovaire, qui est folliculaire chez Archigetes par opposition à compact chez Paraglaridacris.

Diversity of echinostomes (Digenea: Echinostomatidae) in their snail hosts at high latitudes.

The biodiversity of freshwater ecosystems globally still leaves much to be discovered, not least in the trematode parasite fauna they support. Echinostome trematode parasites have complex, multiple-host life-cycles, often involving migratory bird definitive hosts, thus leading to widespread distributions. Here, we examined the echinostome diversity in freshwater ecosystems at high latitude locations in Iceland, Finland, Ireland and Alaska (USA). We report 14 echinostome species identified morphologically and molecularly from analyses of nad1 and 28S rDNA sequence data. We found echinostomes parasitising snails of 11 species from the families Lymnaeidae, Planorbidae, Physidae and Valvatidae. The number of echinostome species in different hosts did not vary greatly and ranged from one to three species. Of these 14 trematode species, we discovered four species (Echinoparyphium sp. 1, Echinoparyphium sp. 2, Neopetasiger sp. 5, and Echinostomatidae gen. sp.) as novel in Europe; we provide descriptions for the newly recorded species and those not previously associated with DNA sequences. Two species from Iceland (Neopetasiger islandicus and Echinoparyphium sp. 2) were recorded in both Iceland and North America. All species found in Ireland are new records for this country. Via an integrative taxonomic approach taken, both morphological and molecular data are provided for comparison with future studies to elucidate many of the unknown parasite life cycles and transmission routes. Our reports of species distributions spanning Europe and North America highlight the need for parasite biodiversity assessments across large geographical areas.

TITLE: Diversité des Échinostomes (Digenea, Echinostomatidae) chez leurs hôtes mollusques aux latitudes élevées. ABSTRACT: La biodiversité des écosystèmes d'eau douce à l'échelle mondiale laisse encore beaucoup à découvrir, notamment dans la faune parasitaire des trématodes qu'ils abritent. Les parasites trématodes Échinostomes ont des cycles de vie complexes à hôtes multiples impliquant souvent des oiseaux migrateurs comme hôtes définitifs, conduisant ainsi à des distributions étendues. Ici, nous avons examiné la diversité des échinostomes dans les écosystèmes d'eau douce à des latitudes élevées en Islande, Finlande, Irlande et en Alaska (États-Unis). Nous rapportons de séquences de nad1 et d'ADNr 28S morphologiquement et moléculairement à partir d'analyses de données de séquence d'ADNr nad1 et 28S. Nous avons trouvé des échinostomes parasitant les mollusques de 11 espèces des familles Lymnaeidae, Planorbidae, Physidae et Valvatidae. Le nombre d'espèces d'échinostomes dans différents hôtes ne variait pas beaucoup et allait d'une à trois espèces. Sur ces 14 espèces de trématodes, nous avons découvert quatre espèces (Echinoparyphium sp. 1, Echinoparyphium sp. 2, Neopetasiger sp. 5, Echinostomatidae gen. sp.) comme nouvelles pour l'Europe; nous fournissons des descriptions pour les espèces nouvellement signalées et celles qui n'étaient pas précédemment associées à des séquences d'ADN. Deux espèces d'Islande (Neopetasiger islandicus et Echinoparyphium sp. 2) ont été signalées en Islande et en Amérique du Nord. Toutes les espèces trouvées en Irlande sont de nouveaux signalements pour ce pays. Grâce à une approche taxonomique intégrative, des données morphologiques et moléculaires sont fournies à des fins de comparaison avec des études futures afin d'élucider les nombreux cycles de vie et voies de transmission des parasites, qui sont inconnus. Nos données sur la répartition des espèces en Europe et en Amérique du Nord soulignent la nécessité d'évaluer la biodiversité des parasites dans de vastes zones géographiques.

Molecular evidence of three closely related species of Biacetabulum Hunter, 1927 (Cestoda: Caryophyllidea): a case of recent speciation in different fish hosts (Catostomidae)?

Monozoic tapeworms (Caryophyllidea) are dominant components of parasite communities of suckers (Catostomidae) in North America, with Biacetabulum Hunter, 1927 representing one of the more species-rich genera. Molecular (28S rDNA) and morphological (including scanning electron microscopy and histology) evaluation of newly collected tapeworms from different fish hosts revealed the existence of four similar (and three closely related) species of Biacetabulum. These four species differ from their congeners by having a long body (up to 48 mm long) with a very long, slender neck (its length represents ≥30% of total body length), a large, globular scolex with a prominent central acetabulum-like loculus on the dorsal and ventral sides, two pairs of shallow lateral loculi and a distinct, slightly convex apical disc, and a cirrus-sac that is situated between the anterior arms of the ovarian wings. Taken together, the morphological and molecular data and the host associations of these species provide evidence of their host specificity. Biacetabulum isaureae n. sp. occurs in notch clip redhorse, Moxostoma collapsum, in South Carolina (USA), B. longicollum n. sp. in silver redhorse, Moxostoma anisurum (type host), and golden redhorse, M. erythrurum, in Manitoba (Canada) and West Virginia (USA), B. overstreeti n. sp. in a spotted sucker, Minytrema melanops, in Mississippi, and B. hypentelii n. sp. in northern hogsucker, Hypentelium nigricans, in Tennessee (USA). The new species differ from each other in the number of postovarian vitelline follicles, the posterior extent of preovarian vitelline follicles and relative size of the cirrus sac.

Disentangling taxonomy of Biacetabulum (Cestoda, Caryophyllidea), parasites of catostomid fishes in North America: proposal of Megancestus gen. n. to accommodate B. carpiodi.

A new genus, Megancestus n. gen., is proposed to accommodate the caryophyllidean tapeworm Biacetabulum carpiodi Mackiewicz, 1969 from carpsuckers and quillback (Carpiodes spp.) in North America. This species is not closely related to other species of Biacetabulum Hunter, 1927 and is transferred to a newly erected genus. This new genus is typified by the possession of a small body (total length of 3.1-7.5 mm) with a scolex that bears a pair of large acetabulum-like loculi, two pairs of shallow lateral loculi, and a slightly convex apical disc, testes arranged in one or two layers, oval, thick-walled cirrus-sac, well-developed external seminal vesicle, separate gonopores, H-shaped ovary, few median vitelline follicles, and the uterus extending by a single loop anterior to the cirrus-sac. Megancestus differs from all Nearctic caryophyllidean genera (family Capingentidae), including Biacetabulum, by vitelline follicles dorsal to the ovary that connect the preovarian and postovarian vitelline fields. The most closely related Hunterella Mackiewicz et McCrae, 1962 differs by shape of the scolex (tholate, i.e., devoid of any loculi), dumbbell-shaped ovary and the uterus not extending anterior to the cirrus-sac. Megancestus carpiodi (Mackiewicz, 1969) n. comb. is the only species of the genus and it is a stenoxenous parasite, which has been found only in the river carpsucker (Carpiodes carpio-type host), quillback (Carpiodes cyprinus) and highfin carpsucker (Carpiodes velifer) (Catostomidae: Ictiobinae) in the lower and middle Mississippi basin.

Molecular and morphological characterisation of the metacercariae of two species of Cardiocephaloides (Digenea: Strigeidae) infecting endemic South African klipfish (Perciformes: Clinidae).

South African clinids are a major component of the temperate intertidal regions that are also known to participate in life cycles and transmission of several groups of parasites. However, the knowledge of trematode diversity of these fishes is incomplete. In this study, two species of Clinus Cuvier, the super klipfish Clinus superciliosus (Linnaeus) and the bluntnose klipfish Clinus cottoides Valenciennes, were collected from six localities along the South African coast and examined for the presence of trematodes. Metacercariae of Cardiocephaloides Sudarikov, 1959 were found in the eye vitreous humour and brain of C. superciliosus and in the eye vitreous humour of C. cottoides. Detailed analyses integrating morphological and molecular sequence data (28S rDNA, ITS2 rDNA-region, and COI mtDNA) revealed that these belong to two species, Cardiocephaloides physalis (Lutz, 1926) and an unknown species of Cardiocephaloides. This study provides the first report of clinid fishes serving as intermediate hosts for trematodes, reveals that the diversity of Cardiocephaloides in South Africa is higher than previously recorded, and highlights the need for further research to elucidate the life cycles of these trematode species. The broad geographical distribution of Cardiocephaloides spp. was confirmed in the present study based on molecular sequence data. The host-parasite interactions between clinid fishes and metacercariae of Cardiocephaloides are yet to be explored.

Resolution of the identity of three species of Diplostomum (Digenea: Diplostomidae) parasitising freshwater fishes in South Africa, combining molecular and morphological evidence.

Reliable data on the diversity of the genus Diplostomum (Digenea: Diplostomidae) parasitising freshwater fishes in South Africa, as well as in Africa, is almost non-existent. Most of the morphology-based identifications of species within this genus reported from Africa require critical revision. The aim of the present study was to determine the diversity of Diplostomum metacercariae in South African fishes applying molecular and traditional morphological techniques. To achieve this aim, a total of 216 fishes belonging to 21 species collected in the Rivers Phongolo, Riet, Usuthu and Mooi in three provinces of South Africa were examined. Metacercariae of Diplostomum were recovered from the eye lenses of 38 fishes belonging to five species of the families Anguillidae, Cichilidae and Mochokidae, with an overall low prevalence of infection (18%). Metacercariae were subjected to morphological study and molecular sequencing of the partial mithochondrial cox1 and ribosomal 28S rDNA genes as well as of ribosomal ITS1-5.8S-ITS2 region. Morphological and phylogenetic analyses revealed the presence of three species which matched those previously reported from Nigeria, Iraq and China, therefore those from Tilapia sparrmanii and Synodontis zambezensis were named Diplostomum sp.; those from Anguilla labiata, Oreochromis mossambicus and S. zambezensis were named Diplostomum sp. 14; and those from Pseudocrenilabrus philander were named Diplostomum sp. 16. Geographic distribution of several species of Diplostomum appeared to be wider than expected. Morphological description and novel sequence data generated during this study will contribute to the elucidation of the life cycles of Diplostomum sp., Diplostomum sp. 14 and Diplostomum sp. 16 and advance further research of diplostomids in Africa.

Novel information on the morphology, phylogeny and distribution of camallanid nematodes from marine and freshwater hosts in South Africa, including the description of Camallanus sodwanaensis n. sp.

Four species of previously known nematodes from the family Camallanidae were found from different hosts in South Africa: Batrachocamallanus xenopodis from the frog Xenopus muelleri, Paracamallanus cyathopharynx and Procamallanus pseudolaeviconchus from the catfish Clarias gariepinus and Spirocamallanus daleneae from the catfish Synodontis zambezensis. In the material collected from various marine fishes, several specimens of nematodes from the genus Camallanus clearly differed from all previously known species. Based on morphological differences these specimens are assigned to a new species, C. sodwanaensis. Molecular data of 18S and 28S rDNA and COI sequences are provided for the collected species and a phylogenetic analyses based on 28S gene fragmets are presented.

Three new species of acanthocephalans (Palaeacanthocephala) from marine fishes collected off the East Coast of South Africa.

Three new species of acanthocephalans are described from marine fishes collected in Sodwana Bay, South Africa: Rhadinorhynchus gerberi n. sp. from Trachinotus botla (Shaw), Pararhadinorhynchus sodwanensis n. sp. from Pomadasys furcatus (Bloch et Schneider) and Transvena pichelinae n. sp. from Thalassoma purpureum (Forsskål). Transvena pichelinae n. sp. differs from the single existing species of the genus Transvena annulospinosa Pichelin et Cribb, 2001, by the lower number of longitudinal rows of hooks (10-12 vs 12-14, respectively) and fewer hooks in a row (5 vs 6-8), shorter blades of anterior hooks (55-63 vs 98), more posterior location of the ganglion (close to the posterior margin of the proboscis receptacle vs mid-level of the proboscis receptacle) and smaller eggs (50-58 × 13 µm vs 62-66 × 13-19 µm). Pararhadinorhynchus sodwanensis n. sp. differs from all known species of the genus by a combination of characters. It closely resembles unidentified species Pararhadinorhynchus sp. sensu Weaver and Smales (2014) in the presence of a similar number of longitudinal rows of hooks on the proboscis (16-18 vs 18) and hooks in a row (11-13 vs 13-14), but differs in the position of the lemnisci (extend to the level of the posterior end of the proboscis receptacle or slightly posterior vs extend to the mid-level of the receptacle), length of the proboscis receptacle (910-1180 µm vs 1,460 µm) and cement glands (870-880 µm vs 335-350 µm). Rhadinorhynchus gerberi n. sp. is distinguishable from all its congeners by a single field of 19-26 irregular circular rows of the tegumental spines on the anterior part of the trunk, 10 longitudinal rows of hooks on the proboscis with 29-32 hooks in each row, subterminal genital pore in both sexes, and distinct separation of the opening of the genital pore from the posterior edge of the trunk (240-480 µm) in females. Sequences for the 18S rDNA, 28S rDNA and cox1 genes were generated to molecularly characterise the species and assess their phylogenetic position. This study provides the first report based on molecular evidence for the presence of species of Transvena Pichelin et Cribb, 2001 and Pararhadinorhynchus Johnston et Edmonds, 1947 in African coastal fishes.

Morphological and molecular evidence for synonymy of Corynosoma obtuscens Lincicome, 1943 with Corynosoma australe Johnston, 1937 (Acanthocephala: Polymorphidae).

Corynosoma obtuscens Lincicome, 1943 (Acanthocephala: Polymorphidae) is synonymised with Corynosoma australe Johnston, 1937 based on combined morphological and molecular evidence. Morphological comparison of C. obtuscens (24 males and 27 females) collected from a California sea lion Zalophus californianus (Lesson) in California, USA, with the type-specimens of C. obtuscens and C. australe, and with published data on C. australe collected from different hosts and regions showed no significant differences. The levels of genetic divergence in the cox1 sequences obtained from C. obtuscens from a California sea lion in the present study and C. australe from otariid seals from Argentina and penguins from Brazil ranged between 1.4-1.6% and was considered to represent intraspecific variability. Additionally, cox1 sequences were generated for Andracantha phalacrocoracis (Yamaguti, 1939), Corynosoma semerme (Forssell, 1904), C. strumosum (Rudolphi, 1802), C. validum Van Cleave, 1953 and C. villosum Van Cleave, 1953. Our results revealed inconsistency in the identification of material used as a source of the previously published sequence data for C. obtuscens and C. magdaleni Montreuil, 1958.