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Cancer is one of the leading causes of death, with an estimated 19.3 million new cases and 10 million deaths worldwide in 2020 alone. Approximately 2.2 million cancer cases are attributed to infectious diseases, according to the World Health Organization (WHO). Despite the apparent involvement of some parasitic helminths (especially trematodes) in cancer induction, there are also records of the potential suppressive effects of helminth infections on cancer. Tapeworms such as Echinococcus granulosus , Taenia crassiceps , and more seem to have the potential to suppress malignant cell development, although in a few cases the evidence might be contradictory. Our review aims to summarize known epidemiological data on the cancer-helminth co-occurrence in the human population and the interactions of tapeworms with cancers, i.e ., proven or hypothetical effects of tapeworms and their products on cancer cells in vivo ( i.e ., in experimental animals) or in vitro . The prospect of bioactive tapeworm molecules helping reduce the growth and metastasis of cancer is within the realm of future possibility, although extensive research is yet required due to certain concerns., Competing Interests: The authors declare that they have no competing interests., (© 2024 Schreiber et al.)

Two new species of Scyphophyllidium Woodland, 1927 are described from the Hooktooth shark, Chaenogaleus macrostoma (Bleeker), from the Persian Gulf, Iran. Scyphophyllidium hormuziense n. sp. is assigned to morphological category 2 of its genus because it possesses bothridial marginal loculi and an apical sucker on each flat bothridium, and lacks bothridial facial loculi. Within category 2, it is distinguished from its congeners, except for S. janineae (Ruhnke, Healy and Shapero, 2006), by possessing, rather than lacking, a prominent cephalic peduncle. It differs from S. janineae in the distribution of the vitelline follicles. Scyphophyllidium iraniense n. sp. is assigned to morphological category 5 because its bothridia are essentially flat and lack proximal apertures, marginal loculi, facial loci and semi-circular muscle bands, and bears weakly serrate gladiate spinitriches on its distal bothridial surfaces. Within its morphological category, the presence of a long cephalic peduncle distinguishes S. iraniense n. sp. from its congeners lacking this structure or possessing a short cephalic peduncle. It further differs from S. arnoldi (Ruhnke and Thompson, 2006) and S. typicum (Subhapradha, 1955) in total length, from S. paulum (Linton, 1897) in lacking a conspicuous band of muscles along the locular periphery of the bothridia, and from S. kirstenae (Ruhnke, Healy and Shapero, 2006) in the distribution of the vitelline follicles. This study brings the number of the valid Scyphophyllidium species of the Persian Gulf to five., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Via molecular and morphological analyses, we describe adult specimens of a new species of Versteria (Cestoda: Taeniidae) infecting mink and river otter (Carnivora: Mustelidae) in Western Canada, as well as larval forms from muskrat and mink. These sequences closely matched those reported from adult specimens from Colorado and Oregon, as well as larval infections in humans and a captive orangutan. We describe here a new species from British Columbia and Alberta (Canada), Versteria rafei n. sp., based upon morphological diagnostic characteristics and genetic distance and phylogeny. Versteria rafei n. sp. differs from the three other described species of the genus in the smaller scolex and cirrus sac. It also differs from V. mustelae (Eurasia) and V. cuja (South America) by having an armed cirrus, which is covered in hair-like bristles, and in the shape of its hooks, with a long thorn-like blade, and short or long handle ( vs. a short sharply curved blade and no difference in handle size in previously described species). The poorly known V. brachyacantha (Central Africa) also has an armed cirrus and similarly shaped hooks. However, it differs from the new species in the number and size of hooks. Phylogenetic analysis of the cox1 and nad1 mitochondrial regions showed that our specimens clustered with isolates from undescribed adults and larval infections in North America, and separate from V. cuja , confirming them to be a distinct species from the American Clade.

This paper provides new morphological and molecular data for identifying Monoecocestus species from rodents: a) morphological update of Monoecocestus spp., b) morphological data on Anoplocephalidae taxa from Sigmodontinae rodents, c) analyses of the genetic distances between the specimens studied and other Anoplocephalidae from rodents available in GenBank, and phylogenetic inferences. A total of 25 specimens of Holochilus spp. were examined from four provinces of Argentina. Cestodes specimens were removed from the rodents small intestines. Conventional studies were used for the morphological and molecular analysis. Four taxa of Monoecocestus were identified. Monoecocestus threlkeldi was identified as first record in Holochilus chacarius and from Argentina. Molecular and morphological aspects of Monoecocestus sp.1, Monoecocestus sp.2 and Monoecocestus sp.3 were described. Specimens belonging to the genus Monoecocestus may represent closely related species, demonstrating the importance of using integrative taxonomic approaches to understand biological diversity. The continuity of the studies on Anoplocephalidae will allows to advance in investigation of molecular analyses and ecological aspects that determine parasite-host-environment relationship.

Background: Spirometra mansoni can parasitize animals and humans through food and water, causing parasitic zoonosis. Knowledge of the developmental process of S. mansoni is crucial for effective treatment; thus, it is important to characterize differential and specific proteins and pathways associated with parasite development., Methods: In this study, we performed a comparative proteomic analysis of the plerocercoid and adult stages using a tandem mass tag-based quantitative proteomic approach. Additionally, integrated transcriptomic and proteomic analyses were conducted to obtain the full protein expression profiles of different life cycle stages of the tapeworm., Results: Approximately 1166 differentially expressed proteins (DEPs) were identified in adults versus plerocercoids, of which 641 DEPs were upregulated and 525 were downregulated. Gene Ontology (GO), Clusters of Orthologous groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses indicated that most DEPs related to genetic information processing and metabolism of energy in adults seem to be more activated. In the plerocercoid stage, compared to metabolism, genetic information processing appears more dynamic. Protein-protein interaction (PPI) revealed six key proteins (phosphomannomutase, glutathione transferase, malate dehydrogenase, cytoplasmic, 40S ribosomal protein S15, ribosomal protein L15 and 60S acidic ribosomal protein P2) that may play active roles in the growth and development of S. mansoni. Finally, the combination of transcriptomic and proteomic data suggested that three pathways (ubiquitin-mediated proteolysis, phagosome and spliceosome) and five proteins closely related to these pathways might have a significant influence in S. mansoni., Conclusions: These findings contribute to increasing the knowledge on the protein expression profiles of S. mansoni and provide new insights into functional studies on the molecular mechanisms of the neglected medical tapeworm., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Human diplogonoporiasis caused by the tapeworm Diplogonoporus balaenopterae has been rarely reported in Japan in the last decade. A 38-year-old man complained of a fever, diarrhea, intermittent abdominal pain, and worm excretion. He had a history of consuming raw juvenile Japanese anchovy one month earlier. On admission, the patient had acute enteritis and received intravenous fluids. During hospitalization, he excreted a white worm in his stool. On a macroscopic examination, the worm was found to be a tapeworm with scolexes. His health improved spontaneously without taking anthelmintic agents. Based on the genetic analysis, the tapeworm was identified as Diplogonoporus balaenopterae.

Introduction: Branchiopodataenia bazaletica sp. n. (Cestoda, Cyclophyllidea) is described from the black tern, Chlidonias niger L., after re-examination of material deposited in the helminthological collection of the Institute of Zoology, Ilia State University, Institute of Zoology in Tbilisi, Georgia., Methods: The cestodes were collected from Bazaleti Lake in Georgia and originally identified as Wardium cirrosa, as labeled on the slides. Cestodes were examined using light microscopy., Results: Detailed examination of the morphology of these specimens showed that they belong to the genus Branchiopodataenia and are described as a new species. The presence of 10 aploparaksoid hooks with an elongate handle, three testes, and chitinoid latch-like structure in the copulative part of the vagina support the assignment of the new species to Branchiopodataenia. The new species has rostellar hooks 48-52 in length, a long, armed cirrus, and long copulative part of the vagina. Branchiopodataenia bazaletica sp. n. differs from its congeners by the size of rostellar hooks and by the shape of the cirrus and vagina., (© 2022. The Author(s) under exclusive licence to Witold Stefański Institute of Parasitology, Polish Academy of Sciences.)

Dibothriocephalus latus is the most frequent causative agent of fish-borne zoonosis (diphyllobothriosis) in Europe, where it is currently circulating mainly in the Alpine lakes region (ALR) and Russia. Three mitochondrial genes ( cox 1, cob and nad 3) and 6 microsatellite loci were analysed to determine how is the recently detected triploidy/parthenogenesis in tapeworms from ALR displayed at the DNA level. A geographically distant population from the Krasnoyarsk Reservoir in Russia (RU-KR) was analysed as a comparative population. One or 2 alleles of each microsatellite locus was detected in plerocercoids from RU-KR, corresponding to the microsatellite pattern of a diploid organism. In contrast, 1–3 alleles were observed in tapeworms from ALR, in accordance with their triploidy. The high diversity of mitochondrial haplotypes in D. latus from RU-KR implied an original and relatively stable population, but the identical structure of mitochondrial genes of tapeworms from ALR was probably a consequence of a bottleneck typical of introduced populations. These results indicated that the diploid/sexually reproducing population from RU-KR was ancestral, located within the centre of the distribution of the species, and the triploid/parthenogenetically reproducing subalpine population was at the margin of the distribution. The current study revealed the allelic structure of the microsatellite loci in the triploid tapeworm for the first time.

Rodents are hosts of a wide diversity of cestodes. Fifteen genera included in the family Hymenolepididae parasitize rodents, and only four of these genera have been recorded from the Neotropical region. The purpose of this paper is to update species of Hymenolepididae from rodents, describe a new species of Hymenolepis based on morphological and molecular characterization (ITS1 rDNA and cox1 mtDNA), comparing the features among the species from North and South American rodents, and provide phylogenetic inferences of Hymenolepididae from rodents based on sequences available in the GenBank. Rodents were collected in the Parque Provincial Ernesto Tornquist, Buenos Aires, Argentina. Hymenolepis ivanovae n. sp. differs from other Hymenolepis species registered from North and South American rodents by body size, scolex, suckers, cirrus sac, cirrus, testes, and eggs, among others. Comparative morphometric data for Hymenolepis species from North and South American rodents is provided. Molecular analyses place H. ivanovae n. sp. within the genus Hymenolepis with strong support, and show it close to species of zoonotic importance. The new species is the first species of Hymenolepis described from Sigmodontinae rodents., (Copyright © 2022 Elsevier B.V. All rights reserved.)

An annotated checklist of the helminth parasites associated with reptiles from Peru is provided, as the result of a compilation of parasitological papers published between 1963 and January 2022 and records of species deposited in national and international collections. The list provides data on hosts, developmental stage, sites of infection, geographical distribution in Peruvian territory, code of material deposited in helminthological collections, references and taxonomic notes. The database includes records of 106 different species of helminth parasites (82 nominal species and 24 taxa identified at the generic level), the majority in the adult stage. These helminth parasites come from 18 of the 25 official Peruvian regions. Nematodes have the highest richness in number of species (79 species), followed by trematodes (17 species) and cestodes (nine species). The acanthocephalans are represented by only one species. The parasites with the highest number of records were Physaloptera retusa Rudolphi, 1819 (11 hosts), Physalopteroides venancioi (Lent, Freitas & Proença, 1946) (nine hosts), Strongyluris oscari Travassos, 1923 (seven hosts), and Parapharyngodon scleratus Travassos, 1923 (five hosts), all of which are nematodes. The 106 taxa of helminth parasites have been reported infecting 55 species of reptiles in Peru, distributed in 34 genera and 14 families. The reptile species harbouring the highest number of helminth parasites are the yellow-footed tortoise Chelonoidis denticulatus (Linnaeus) with 18 species (three trematodes and 15 nematodes), followed by the Peru desert tegu Dicrodon guttulatum Duméril & Bibron (Teiidae) with 11 species (three cestodes and eight nematodes) and the yellow-spotted Amazon River turtle Podocnemis unifilis Troschel (Podocnemididae) with 10 species (five trematodes and five nematodes). Of the 524 species of reptiles reported in Peru, only 55 (>10%) are reported as hosts of helminths representing a small proportion considering the great variety of reptile hosts that inhabit the various tropical and subtropical geographical areas of Peru.

Competing Interests: Declaration of interests The authors declare no competing interests.

Echinococcus multilocularis is the etiological agent of alveolar echinococcosis (AE), a serious parasitic disease in the Northern Hemisphere. The E. multilocularis primary cell cultivation system, together with E. multilocularis genome data and a range of pioneering molecular-based tools have advanced the research on this and other cestodes. RNA interference (RNAi) and microRNA knock-down have recently contributed to the study of the cellular and molecular basis of tapeworm development and host-parasite interaction. These, as well as other techniques, normally involve an electroporation step for the delivery of RNA, DNA, peptides, and small molecules into cells. Using transcriptome data and bioinformatic analyses, we herein report a genome-wide comparison between primary cells of E. multilocularis and primary cells under electroporated conditions after 48 h of culture. We observed that ~ 15% of genes showed a significant variation in expression level, including highly upregulated genes in electroporated cells, putatively involved in detoxification and membrane remodeling. Furthermore, we found genes related to carbohydrate metabolism, proteolysis, calcium ion binding and microtubule processing significantly altered, which could explain the cellular dispersion and the reduced formation of cellular aggregates observed during the first 48 h after electroporation., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Since 2010, the trypanorhynch tapeworm family Rhinoptericolidae Carvajal & Campbell, 1975 has housed just two distinctive, monotypic genera ( Rhinoptericola Carvajal & Campbell, 1975 and Nataliella Palm, 2010). However, global collections of tapeworms from sharks and rays over the last more than three decades brought to light the need for major revision of the family by suggesting a much greater species-level diversity for the nominal genus Rhinoptericola . Through synonymy and the description of new species, the number of species in the genus is increased from one to eight. A phylogenetic analysis of the D1-D3 gene region of 28S rRNA (28S), including seven of the now nine species of rhinoptericolids, and a broad sampling of the other Trypanobatoida is the first to recover a monophyletic Rhinoptericolidae. In addition to systematic revision, this study allowed for the first evaluation of the degree of intraspecific vs interspecific variation in 28S for adult trypanorhynchs across the various hosts and geographic localities from which they have been reported, suggesting a relatively consistent boundary for Rhinoptericola . It is further suggested that detailed scanning electron microscopy (SEM) images of both the basal and metabasal armatures greatly aid in the interpretation of hook arrangement and shape. A schematic to streamline determination of the tentacular surface presented in scanning electron micrographs and line drawings of trypanorhynchs is presented for species with both two and four bothria. In combination, these methodological refinements can now be used as a model to resolve issues of classification and non-monophyly within both major lineages of the Trypanorhyncha. As a result of the taxonomic work, Rhinoptericola megacantha Carvajal & Campbell, 1975 (previously only known from the American cownose ray from the Chesapeake Bay and the Ticon cownose ray from the Gulf of Mexico, Venezuela, and Brazil) is now known from an additional species of cownose ray and a species of stingray, and is revealed to have a transatlantic distribution. Data from SEM suggest a simpler interpretation of hook arrangement in the metabasal armature for Rhinoptercola and-in combination with 28S sequence data-support Shirleyrhynchus Beveridge & Campbell, 1988 (a former rhinoptericolid) as its junior synonym. The three species formerly assigned to Shirleyrhynchus are thus transferred to Rhinoptericola . Data from light microscopy on whole-mounted specimens and histological sections, SEM, and 28S showed the eutetrarhynchid Prochristianella jensenae Schaeffner & Beveridge, 2012b to be morphologically consistent with species of Rhinoptericola and it is thus transferred to the genus. The type series of P. jensenae was determined to be mixed, representing two distinct species which are here redescribed and described as new, respectively. Two additional novel species of Rhinoptericola are described from cownose rays from off Mozambique and the Gulf of California., Competing Interests: The authors declare that they have no competing interests., (© 2022 Herzog and Jensen.)

The sampling of 22 specimens of Rhizoprionodon oligolinx Springer from the Persian Gulf made possible the description of three new species of Anthobothrium van Beneden, 1850. Anthobothrium parimae sp. nov. is different from its congeners, except for A. altavelae Neifar, Euzet and Ben Hassine, 2002, A. lyndoni Ruhnke and Caira, 2009, and A. lesteri Williams, Burt and Caira, 2004, in the total length. It differs from A. altavelae in the number of the proglottids; from A. lyndoni in the length of the mature proglottids; and from A. lesteri Williams, Burt and Caira, 2004 in possessing one hemicircular band, rather than two circular bands, of musculature in its bothridia. The other two new species, being the smallest in size within the genus, most closely resemble each other but differ in the position of the genital pore in the proglottid, the number of post-vaginal testes, the number of the ventral and dorsal columns of vitelline follicles in each lateral band, and the distribution of the gladiate spinitriches on the strobila. These three new species are the only "tetraphyllidean" species reported to date from the southern waters of Iran. In addition, for the first time, more than two congeners belonging to Anthobothrium are reported from the same host species sympatrically and simultaneously. The morphological variation within this genus is also discussed., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The oncosphere larvae of tapeworms cyclically extend and retract their hooks during the penetration of the intestine of their intermediate hosts. The mechanisms regulating these movements are essentially unknown, in part due to the biohazardous nature of oncospheres from human pathogens. In this work, we standardized a method for the analysis of motility of hatched oncospheres (hexacanths) of the model tapeworm Hymenolepis microstoma. We used this assay to explore the relevance of protein kinases C (PKC) and A (PKA) in these processes. Pharmacological inhibition of the PKC pathway resulted in impaired larval motility. On the other hand, the PKA inhibitor H-89 potently blocked larval motility, as well as the motility of other life stages, although other inhibitors of the PKA pathway were not effective. This work represents the first study of the mechanisms that regulate the motility of oncospheres, and provides a path for further exploration., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Antagonistic interactions between hosts and parasites may drive the evolution of novel host defenses, or new parasite strategies. Host immunity is therefore one of the fastest evolving traits. But where do the novel immune traits come from? Here, we test for phylogenetic conservation in a rapidly evolving immune trait-peritoneal fibrosis. Peritoneal fibrosis is a costly defense against a specialist tapeworm, Schistocephalus solidus (Cestoda), expressed in some freshwater populations of threespine stickleback fish (Gasterosteus aculeatus, Perciformes). We asked whether stickleback fibrosis is a derived species-specific trait or an ancestral immune response that was widely distributed across ray-finned fish (Actinopterygii) only to be employed by threespine stickleback against the specialist parasite. We combined literature review on peritoneal fibrosis with a comparative experiment using either parasite-specific, or nonspecific, immune challenge in deliberately selected species across fish tree of life. We show that ray-finned fish are broadly, but not universally, able to induce peritoneal fibrosis when challenged with a generic stimulus (Alum adjuvant). The experimental species were, however, largely indifferent to the tapeworm antigen homogenate. Peritoneal fibrosis, thus, appears to be a common and deeply conserved fish immune response that was co-opted by stickleback to adapt to a new selective challenge., (© 2021 The Authors. Evolution published by Wiley Periodicals LLC on behalf of The Society for the Study of Evolution.)

Here, we present a draft genome of the tapeworm Dipylidium caninum (family Dipylidiidae) and compare it with other cestode genomes. This draft genome of D. caninum is 110 Mb in size, has a repeat content of ~13.4% and is predicted to encode ~10,000 protein-coding genes. We inferred excretory/secretory molecules (representing the secretome), other key groups of proteins (including peptidases, kinases, phosphatases, GTPases, receptors, transporters and ion-channels) and predicted potential intervention targets for future evaluation. Using 144 shared single-copy orthologous sequences, we investigated the genetic relationships of cestodes for which nuclear genomes are available. This study provides first insights into the molecular biology of D. caninum and a new resource for comparative genomic and genetic explorations of this and other flatworms., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Two new species of the cestode genus Caulobothrium, collected from the duckbill eagle ray, Aetomylaeus bovinus, off Senegal, are described. Although postulated as sister taxa in an earlier molecular phylogenetic analysis, Caulobothrium multispelaeum n. sp. and Caulobothrium katzi n. sp., respectively, are among the smallest and largest members of the genus. The smaller species is unique among its congeners in possessing unusual medial longitudinal grooves along the dorsal and ventral surfaces of its strobila that develop into a tandem series of elliptical apertures on the posterior proglottids. The inner surfaces of these apertures stained positively with McManus' periodic acid Schiff in a manner similar to that seen in members of the distantly related lecanicephalidean genus Elicilacunosus. The larger species differs from its congeners in size, number of proglottids, and arrangement of bothridial loculi. Both new species were found to possess a small apical sucker on the anterior margin of each of their bothridia. Scanning electron microscopy (SEM) and frontal sections of a bothridium of Caulobothrium tetrascaphium suggests that this species also bears an apical sucker. Examination of the hologenophore of the species provisionally referred to as Caulobothrium n. sp. 5 in the earlier molecular analysis indicates it is conspecific with the recently described Caulobothrium pedunculatum, which was also determined to possess bothridial apical suckers. This leads us to suspect that this feature may be found to occur in all members of the genus. SEM of specimens of Caulobothrium for the first time indicates their bothridial surfaces are covered with filitriches of various sizes but lack spinitriches; spinitriches were seen only on the cephalic peduncle of C. katzi n. sp. The geographic distribution and host associations of Caulobothrium are expanded to include data now available for all species. The diagnosis of the genus is revised to include all of this information.

Species diversity and interrelationships of tapeworms of the genus Kapsulotaenia Freze, 1963 (Proteocephalidae: Acanthotaeniinae), parasites of lizards, especially monitors (Varanus spp.) in the Australasian region, were re-assessed using an interdisciplinary approach. Molecular phylogenetic analyses of newly characterized lsrDNA and cox1 sequences confirmed monophyly of the genus, which is typified by the presence of eggs in capsules, and also indicated a strict (oioxenous) level of host specificity of its species thus revealing unexpected species diversity. Diagnoses of insufficiently described species were amended based on a study of the types and freshly collected specimens and, in addition, three new species were described. A list of ten species of the genus recognized as valid is provided, including illustrations of taxonomically important structures of poorly known taxa. Kapsulotaenia beveridgei n. sp. from V. rosenbergi in Australia differs from all other species of Kapsulotaenia but K. frezei and K. saccifera by having a lower number of testes and an absence of banana-shaped clusters of eggs. Kapsulotaenia cannoni n. sp. from V. gouldii can be distinguished from all species but K. chisholmae by a smaller scolex diameter and from all remaining species by its bigger cirrus-sac ratio and a bigger Mehlis' gland/proglottid width ratio. Kapsulotaenia cannoni n. sp. differs from K. chisholmae, by the presence of an armed cirrus and a lower number of eggs in cluster (3-7 versus 8-13). Kapsulotaenia nybelini n. sp., which also occurs in V. gouldii, differs from K. tidswelli, K. frezei and K. beveridgei by having a greater number of testes, and it differs from K. varia by having a smaller relative size of the ovary. It differs from K. saccifera by the absence of banana-shaped cluster, and from K. pythonis by the number of eggs in clusters. Identification keys for all species of Kapsulotaenia and genera of the Acanthotaeniinae are also provided, together with SEM micrographs of three species, including two newly described species.

Two new cestodes of the family Hymenolepididae are described from two species of rodents of the family Geomyidae collected in Mexico and Costa Rica. One new species of Hymenolepis is described from Cratogeomys planiceps Merriam 1895 from near Toluca, Mexico and another that we allocate to a new genus is described from Heterogeomys heterodus (Peters, 1865) from near Irazú Volcano, Costa Rica. Hymenolepis s. str. includes those Hymenolepididae with an apical organ, with no hooks on suckers or apical organ, and three testes. Hobergia irazuensis n. gen., n. sp. includes a hymenolepidid with an apical organ, unarmed scolex, small pockets termed foveolae, in which the suckers completely retract, and extremely bi-lobed ovary. Multivariate morphometric analysis showed good separation of these species from all other hymenolepidids possessing an apical organ and lacking a well developed rostellum and rostellar hooks in the Nearctic and Neotropical regions.

Three new species of Acanthobothrium Blanchard, 1848 (Onchoproteocephalidea: Onchobothriidae) are described from Pacific coastal waters of Mexico. Based on four criteria for categorization of species of Acanthobothrium, the three new species belong to Category 2 species, characterized by their total length (< 15 mm), number of proglottids (< 50) and testes (<80), and with asymmetrical ovary. Acanthobothrium ppdeleoni n. sp. from diamond stingray Hypanus dipterurus (Jordan Gilbert) is differentiated from congeners by a combination of characters including total length of the whole worms, size of the scolex and bothridia, length of the bases of the hooks and abaxial prongs, and the size of the cirrus sacs in mature proglottids. Acanthobothrium hypanus n. sp. and A. sinaloaensis n. sp. are described from longtail stingray Hypanus longus (Garman). Acanthobothrium hypanus n. sp. is differentiated by a combination of characters including size of the scolex and bothridia, diameter of the accessory sucker, length of the abaxial prongs, size of the cirrus sacs and testes in mature proglottids. Acanthobothrium sinaloaensis n. sp. is differentiated by a combination of characters including size of the scolex and bothridia, diameter of the accessory sucker, size of the cirrus sacs in mature proglottids, number of immature proglottids, number of testes, the length of the lobes of the ovary and the absence of velum between medial margin of bothridia. Thirteen species of Acanthobothrium have been reported previously from elasmobranchs from the Pacific coast of Mexico. In the present study, the number of species is elevated to 16.

Parasites are important selective agents with the potential to limit gene flow between host populations by shaping local host immunocompetence. We report on a contact zone between lake and river three-spined sticklebacks (Gasterosteus aculeatus) that offers the ideal biogeographic setting to explore the role of parasite-mediated selection on reproductive isolation. A waterfall acts as a natural barrier and enforces unidirectional migration from the upstream river stickleback population to the downstream river and lake populations. We assessed population genetic structure and parasite communities over four years. In a set of controlled experimental infections, we compared parasite susceptibility of upstream and downstream fish by exposing laboratory-bred upstream river and lake fish, as well as hybrids, to two common lake parasite species: a generalist trematode parasite, Diplostomum pseudospathaceum, and a host-specific cestode, Schistocephalus solidus. We found consistent genetic differentiation between upstream and downstream populations across four sampling years, even though the downstream river consisted of ~10% first-generation migrants from the upstream population as detected by parentage analysis. Fish in the upstream population had lower genetic diversity and were strikingly devoid of macroparasites. Through experimental infections, we demonstrated that upstream fish and their hybrids had higher susceptibility to parasite infections than downstream fish. Despite this, naturally sampled upstream migrants were less infected than downstream residents. Thus, migrants coming from a parasite-free environment may enjoy an initial fitness advantage, but their descendants seem likely to suffer from higher parasite loads. Our results suggest that adaptation to distinct parasite communities can influence stickleback invasion success and may represent a barrier to gene flow, even between close and connected populations., (© 2019 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)

The cestode Hymenolepis diminuta is highly prevalent in wild rat populations and has also been observed rarely in humans, generally causing no apparent harm. The organism has been studied for decades in the laboratory, and its colonization of laboratory rats has recently been shown as protective against some inflammation-associated disorders. Recently, H. diminuta has become a leading candidate for helminth therapy, an emerging method of "biota enrichment" used to treat or prevent inflammatory diseases of humans in Western society. While most of the experimental isolates of H. diminuta are identified based on typical morphological features, hymenolepidid tapeworms may represent complexes of cryptic species as detected by molecular sequence data. In the present study, we explored the diversity of laboratory-kept strains using partial sequences of two genes (lsrDNA and cox1) and determined that H. diminuta isolates currently considered for therapeutic purposes in the US and Europe belong to a single, genetically nearly uniform lineage, showing only little genetic deviation from wild-caught isolates., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Five new species of Acanthobothrium Blanchard, 1848 are described from Gymnura cf. poecilura from the Gulf of Oman and Persian Gulf. They all belong to the Category 1 and can be differentiated from all congeners by a combination of characters, including marginal lappets on the bothridial rim, the lack of spinitrich microtriches on the proximal bothridial surfaces, the position of the genital pore in the posterior one fifth of the proglottid, the direction of the cirrus sac parallel and clinging to the ovarian lobe, the lack of post-vaginal testes, and the interruption of the vitelline follicles by the ovary. The five new species are morphologically similar to each other but differ among each other in their cephalic peduncle length, proglottid and testes number, and the apolysis status. The most similar species to this new group is Acanthobothrium fogeli Gloldstein, 1964 from the Gulf of Mexico. The new species differ from A. fogeli by the muscular pad size, cephalic peduncle length and having marginal lappets on the bothridial rim. the species of Acanthobothrium occurs in three families of elasmobranchs in the Gulf of Oman and Persian Gulf (Dasyatidae, Rhynchobatidae and Gymnuridae). The true identity of many hosts in the region is ambiguous. Therefore, we designated the sampled elasmobranch as G cf. poecilura in accordance to the previously molecular study on a few individuals from the region.

Spermatozoon formation in Caryophyllaeides fennica (Schneider, 1902) is characterised by the following: (1) apical electron-dense material in the zone of differentiation, (2) typical striated roots situated unconventionally in opposite directions in early stages of spermiogenesis, (3) intercentriolar body composed of three electron-dense and two electron-lucent plates, (4) free flagellum and a flagellar bud that correspond to a greatly reduced flagellum and (5) rotation of free flagellum and a flagellar bud to the median cytoplasmic process at 90°. The development of two flagella of significantly unequal length clearly supports a derived form of spermiogenesis in the Caryophyllidea. New for cestodes is a finding of two additional striated roots situated opposite each other, in conjunction with both the flagellar bud and free flagellum. Mutual position of additional striated roots and typical striated roots is parallel in early stages and perpendicular in advanced stages of spermiogenesis. A complete proximodistal fusion gives rise to a mature spermatozoon consisting of one axoneme, parallel cortical microtubules, a nucleus and a moderately electron-dense cytoplasm with glycogen particles, detected by a technique of Thiéry (J Microsc 6:987-1018, 1967), in the principal regions (II, III, IV). Electron tomography analysis of the free flagellum and one axoneme of a mature spermatozoon of C. fennica provides clear evidence, for the first time, that two tubular structures are present in the central axonemal electron-dense core. Phylogenetically important aspects of spermiogenesis of the Caryophyllidea with one axoneme, and other cestodes with one or two axonemes, are briefly reviewed and discussed.

Reptilian fauna of Australia is extraordinarily rich and diverse, but very little is known about parasites of reptiles, including proteocephalid cestodes of the genus Ophiotaenia La Rue, 1911. In the present survey, data on these parasites are summarised for the first time based on detailed evaluation of all available type and voucher specimens. This survey includes five named species, with four species redescribed, namely O. amphiboluri (Nybelin, 1917), O. longmani Johnston, 1916, O. mjobergi (Nybelin, 1917), and O. striata (Johnston, 1914), and 9 putative new species which are not formally described because of their poor quality and scarce material. An identification key is given for the five named species and unnamed species are briefly characterised with focus on their differential characteristics to facilitate their description as new taxa in the future. Australian species of Ophiotaenia form a monophyletic lineage, whose members share several morphological traits which are absent or rare in other proteocephalids, such as a three-layered embryophore, a scolex with large, anteriorly directed suckers, eggs with thick-walled embryophores, exclusively dorsal and paramuscular position of vitelline follicles, and a postequatorial to equatorial genital pore in most species. A new genus, Australophiotaenia, is proposed to accommodate the species from Australian reptiles that share the above-mentioned characters.

Species of two monotypic genera, Ephedrocephalus Diesing, 1850 and Zygobothrium Diesing, 1850 (Cestoda: Proteocephalidae), parasites of one of the most basal members of the catfish family Pimelodidae, the redtail catfish, Phractocephalus hemioliopterus, in the Neotropical Region, are redescribed based on the evaluation of type specimens and newly collected material. Generic diagnoses are amended to provide a robust baseline for the future re-arrangement of the classification of proteocephalid cestodes. Ephedrocephalus is typified by the medullary position of the ovary and uterus, the cortical distribution of vitelline follicles (dispersed throughout almost the entire ventral cortex) and the testes in one dorsal field. Zygobothrium is primarily characterized by its possession of a robust scolex bearing four uniloculate suckers with two openings each and by the tetralobed velum (laciniations) on every proglottid (two on the ventral and two on the dorsal side). The redtail catfish is the definitive host of as many as seven species of proteocephalid cestodes, which, however, do not represent a monophyletic group. Some species, including Z. megacephalum, are among the earliest diverged parasites of Neotropical catfishes, being closely related to African and North American proteocephalids from catfishes, whereas others such as E. microcephalus belong to more recently diverged taxa with uncertain interrelations. Unlike most proteocephalids of the redtail catfish, which almost always infect the anterior parts of the host intestine, E. microcephalus and Z. megacephalum occur exclusively in its posterior third. A key to the identification of the proteocephalid species parasitizing P. hemioliopterus is also presented.

The role of diseases and parasites has received relatively little attention in modelling ecological dynamics despite mounting evidence of their importance in structuring communities. In contrast to predators, parasites do not necessarily kill their host but instead they may change host life history. Here, we study the impact of a parasite that selectively infects juvenile prey individuals and prevents them from maturing into adults. The model is inspired by the Ligula intestinalis tape worm and its cyprinid fish host Rutilis rutilis. We demonstrate that the parasite can promote as well as demote the so-called stunting in its host population, that is, the accumulation of juvenile prey, which leads to strong exploitation competition and consequently to a bottleneck in maturation. If competition between infected and uninfected individuals is strong, stunting will be enhanced and bistability between a stunted and non-stunted prey population occurs. In this case, the disease competes with the predator of its host species, possibly leading to predator extinction. In contrast, if the competition between infected and uninfected individuals is weak, the stunting is relieved, and epi-zoonotic cycles will occur, with recurrent epidemic outbreaks. Here, the disease facilitates the predator, and predator density will be substantially increased. We discuss the implications of our results for the dynamics and structure of the natural Ligula-Roach system.

Moniezia benedeni and M. expansa are common ruminant tapeworms of worldwide distribution, causing gastrointestinal disorders and even death in sheep and goats. In this study, a polymerase chain reaction- (PCR-) based approach for precise species identification was developed and also applied to faecal DNA diagnosis of the tapeworm infection. Since nuclear ribosomal DNA (rDNA) appears to be a useful target for species and/or strain markers, the 18S regions of the rDNA of M. benedeni and M. expansa were amplified and sequenced. The lengths and GC contents of the regions sequenced were 2476-2487 bp and 51.9-52.1% for M. benedeni and 2473 bp and 51.9-52.0% for M. expansa, respectively. Alignment and comparison of the 18S sequences of the two species showed 92.5-93.3% homology. No matches for the 18S regions of M. benedeni and M. expansa were found with other species by BLAST search, which made the 18S sequences appropriate markers for the design of distinctive primers for the two Moniezia species. Our 18S-based PCR could detect as low levels as 0.5 pg genomic DNA or the DNA extracted from 0.2 g faecal sample collected from the rectum of an M. expansa-infected goat. The results indicate that this PCR approach is a reliable alternative for the differential diagnosis of Moniezia species in faecal samples.

Four types of tetraphyllidean larvae infect cetaceans worldwide: two plerocercoids differing in size, 'small' (SP) and 'large' (LP), and two merocercoids referred to as Phyllobothrium delphini and Monorygma grimaldii. The latter merocercoid larvae parasitize marine mammals exclusively and exhibit a specialised cystic structure. Adult stages are unknown for any of the larvae and thus the role of cetaceans in the life cycle of these species has been a long-standing problem. The SP and LP forms are thought to be earlier stages of P. delphini and M. grimaldii that are presumed to infect large pelagic sharks that feed on cetaceans. A molecular analysis of the D2 variable region of the large subunit ribosomal DNA gene based on several individuals of each larval type collected from three Mediterranean species of cetaceans showed consistent and unique molecular signatures for each type regardless of host species or site of infection. The degree of divergence suggested that LP, P. delphini and M. grimaldii larvae may represent separate species, whereas SP may be conspecific with M. grimaldii. In all host species, individuals of SP accumulated in the gut areas in which the lymphoid tissue was especially developed. We suggest therefore that these larvae use the lymphatic system to migrate to the abdominal peritoneum and mesenteries where they develop into forms recognizable as M. grimaldii. The plerocercoid stage of P. delphini remains unknown. In a partial phylogenetic tree of the Tetraphyllidea, all larvae formed a clade that included a representative of the genus Clistobothrium, some species of which parasitize sharks such as the great white which is known to feed on cetaceans. A bibliographic examination of tetraphyllidean infections in marine mammals indicated that these larvae are acquired mostly offshore. In summary, the evidence suggests that cetaceans play a significant role in the life cycle of these larvae. In addition, it seems clear that cetaceans act as natural intermediate hosts for P. delphini and M. grimaldii, as within these hosts they undergo development from the plerocercoid stage to the merocercoid stage. Because tetraphyllidean species use fish, cephalopods and other marine invertebrates as intermediate hosts, the inclusion of cetaceans in the life cycle would have facilitated their transmission to apex predators such as the large, lamnid sharks. The biological significance of infections of LP in cetaceans is unclear, but infections do not seem to be accidental as such larvae show high prevalence and abundance as well as a high degree of site specificity, particularly in the anal crypts and bile ducts.

We studied experimental double infections of the cestode Schistocephalus solidus in its stickleback host. In particular, we were interested in how two important components of the cestode's transmission success-establishment and growth within the fish host-were affected by the relatedness of the two parasites in a double exposure and by the timing of the two exposures, that is, whether they occurred simultaneously or sequentially. We found that male sticklebacks more often became infected (singly or doubly) if the two cestodes in the exposures were related, whereas female sticklebacks were more easily infected (singly or doubly) when exposed to two unrelated cestodes. Irrespective of the fish's gender, successful infections more often contained both cestodes when they were related. In sequential exposures with related as well as unrelated cestodes, the cestode in the later exposure survived better and also grew larger than the cestode from the first exposure, despite being one week younger. Our results emphasize that within-host dynamics and factors acting at this level can play an important role in determining a parasite's transmission success.

The tegumental structures of two types of tetraphyllidean plerocercoids and two types of merocercoids (Phyllobothrium delphini and Monorygma grimaldii) from Mediterranean striped dolphins, Stenella coeruleoalba, are described for the first time using scanning electron microscopy. The tegument of all of the specimens was fully covered with microtriches. Four basic types were found: filitriches, blade-like spinitriches of different sizes and shapes, cone-shaped spinitriches (with two parallel small projections of equal length at the apex), and crowned cylindrical spinitriches (with 6-7 small papillae forming a crown at the apex); the two latter types are newly described. The two types of plerocercoids had a similar morphology and distribution of microtriches; in addition, cilium-like projections appeared interspersed among the microtriches on the apical sucker, accessory suckers, and distal bothridial loculus. Merocercoids exhibited a greater variety of tegumental structures, especially on the distal bothridial loculus. Both merocercoid types had regularly spaced papillae or "buttons" on the accessory suckers and the distal bothridial loculus that were composed of a central cilium-like projection surrounded by numerous filitriches. However, crowned cylindrical spinitriches were specific to P. delphini and cone-shaped spinitriches were specific to M. grimaldii. Differences in the morphology and distribution of scolex microtriches of adult cestodes have been considered useful for species identification. A previous molecular study has suggested that P. delphini and M. grimaldii are actually different congeneric species. Our study has shown that significant differences in the morphology and distribution of microtriches occur between these species at the merocercoid stage., (Copyright 2005 Wiley-Liss, Inc.)

The need for sentinel organisms reflecting small-scale changes in heavy metal pollution of different habitats has been previously stated and the role of terrestrial mammalian parasites has been pointed out as an important field of research aiming at the potential use of parasitic models as bioindicators. The scope of the present study was to assess the concentration of some toxic (Cd, Pb, As and Hg) elements in Dunas de Mira (Natura 2000 PTCON055) while testing the model constituted by the wild rabbit (Oryctolagus cuniculus Linnaeus, 1758) and its intestinal cestode parasite Mosgovoyia ctenoides Railliet, 1890 as potential bioindicators. Wild rabbits were harvested by hunters and analysed for intestinal cestodes. Samples of kidney, liver, intestinal mucosa, muscle of host and also M. ctenoides were taken and deep-frozen for posterior element analysis by ICP-MS. In general, levels of contamination in rabbit tissues were found to be low although some of the elements were detected in higher quantities when compared to other previous reports for wildlife in Europe. The highest quantity of Pb was found in rabbit muscle (3.81 ppm) while highest Cd and Hg values were found in kidney (1.02 and 0.08 ppm). Significant linear relationships were found between Pb concentration in the parasite and Pb concentration in kidney (P=0.0047), muscle (P=0.0002) and intestinal mucosa (P=0.0181) and between As concentration in the parasite and As concentration in liver (P=0.0024), kidney (P=0.0010), muscle (P=0.0003) and intestinal mucosa (P=0.0047). The most significant relationships for Pb and As were detected between element concentration in the cestode and in host muscle. However, maximum Pb and As concentrations in M. ctenoides were only twice as high as those found for rabbit kidney and therefore it is not possible to confirm the role of the model O. cuniculus/M. ctenoides as a promising bioindicator system unlike other mammalian host/cestode models tested in other studies. The contrasting results might be due to differences in the absorption processes in the tegument of different cestode families. Furthermore, the large size of the cestodes used in the present study might also explain the relatively low element concentration values obtained.

Cestode parasites from freshwater (threespine stickleback, Gasterosteus aculeatus), estuarine (brook charr, Salvelinus fontinalis) and marine (Greenland cod, Gadus ogac) fish from northern Quebec, Canada, were used to investigate the hypotheses that cestode parasites are (13)C and (15)N enriched relative to host food sources, but (15)N depleted with respect to host muscle tissue as a result of differential enrichment during the assimilation of common nutrient sources. Cestode parasites and fish were generally similarly enriched in (13)C with respect to common food sources and, in the case of Greenland cod, cestode parasites were (13)C enriched relative to host tissue. Cestode parasites were also generally (15)N enriched with respect to mean host dietary signatures, but depleted with respect to host muscle tissue. In the case of Greenland cod cestode parasites, no significant (15)N enrichment relative to host dietary signature was observed. Cestode parasites appear generally to experience smaller (15)N enrichment than hosts as a result of trophic transfer of common dietary sources. Differential (15)N enrichment patterns in parasites and fish may be attributed to differences in parasite and host metabolism, particularly the anaerobic and aerobic natures of their respective metabolisms. Results imply that isotope enrichment paradigms developed for the study of aquatic foodwebs cannot be routinely applied to quantitatively assess the role of parasites in aquatic foodwebs and that reference to host muscle tissue measures will not allow accurate characterization of parasite foodweb position. Appropriate reference to assimilated food sources is required to accurately estimate parasite isotopic enrichment patterns and to determine parasite trophic position relative to the host.