Based on previous molecular phylogenetic analyses, Bothriocestus n. gen. is erected to accommodate bothriocephalid tapeworms that have an elongate scolex, a well-developed apical disc, and a narrow neck region, parasitize freshwater fishes in the Holarctic, and were previously placed in the polyphyletic genus Bothriocephalus Rudolphi, 1808 (Cestoda: Bothriocephalidea). Bothriocestus claviceps (Goeze, 1782) n. comb., a parasite of eels (Anguilla spp.) in the Holarctic region, is designated as the type species. Another species of the new genus, Bothriocestus cuspidatus (Cooper, 1917) (syn. Bothriocephalus cuspidatusCooper, 1917) is redescribed from type and voucher specimens, and new material from the type host, the walleye, Sander vitreus (Mitchill, 1818) (Perciformes: Percidae), in Manitoba and Ontario (where the type locality is located) (Canada) and in New York state and Wisconsin. Bothriocestus cuspidatus of S. vitreus is characterized primarily by the possession of a narrow, long strobila (total length up to 18 cm) composed of distinctly craspedote, trapezoidal proglottids, with primary, secondary, and tertiary proglottids differing in size, and by an arrow-shaped (=cuspidatus) scolex that is distinctly broader than the first proglottids, widest near the base in lateral view and gradually becoming broader toward the anterior end in dorsoventral view. A "dwarf" form of B. cuspidatus (total length of 9-27 mm) from Johnny darter, Etheostoma nigrum Rafinesque, 1820, and tessellated darter, Etheostoma olmstedi Storer, 1842 (both Percidae: Etheostominae), is also characterized morphologically in the present paper.

• Keywords
• Canada, Fish, Intraspecific variability, Morphology, Percidae, Tapeworms, Taxonomy, USA,
• MeSH
• Cestoda * MeSH
• Cestode Infections * veterinary   parasitology   MeSH
• Phylogeny MeSH
• Fish Diseases * parasitology   MeSH
• Perches * parasitology   MeSH
• Perciformes * parasitology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Geographicals
• Ontario MeSH
• North America MeSH

The tapeworms of fishes (Chondrichthyes and Actinopterygii) account one-third (1670 from around 5000) of the total tapeworm (Platyhelminthes: Cestoda) species diversity. In total 1186 species from 9 orders occur as adults in elasmobranchs (sharks, rays and chimaeras), and 484 species from 8 orders mature in ray-finned fishes (referred to here as teleosts). Teleost tapeworms are dominated by freshwater species (78%), but only 3% of elasmobranch tapeworms are known from freshwater rays of South America and Asia (Borneo). In the last 2 decades, vast progress has been made in understanding species diversity, host associations and interrelationships among fish tapeworms. In total, 172 new species have been described since 2017 (149 from elasmobranchs and 23 from teleosts; invalidly described taxa are not included, especially those from the Oriental region). Molecular data, however, largely limited to a few molecular markers (mainly 28S rDNA, but also 18S and cox1), are available for about 40% of fish tapeworm species. They allowed us to significantly improve our understanding of their interrelationships, including proposals of a new, more natural classification at the higher-taxonomy level (orders and families) as well as at the lower-taxonomy level (genera). In this review, we summarize the main advances and provide perspectives for future research.

• Keywords
• DNA sequencing, Distribution, elasmobranchs, host associations, pathogens, phylogenetic relationships, ray-finned fish, species diversity, taxonomy,
• MeSH
• Cestoda * genetics   MeSH
• Cestode Infections * epidemiology   veterinary   MeSH
• Diphyllobothrium * MeSH
• Elasmobranchii * MeSH
• Phylogeny MeSH
• Fish Diseases * epidemiology   MeSH
• Fishes MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH

Infection of non-indigenous pumpkinseed (Lepomis gibbosus, Centrarchidae) with the bothriocephalidean cestode Bothriocephalus claviceps (Cestoda: Bothriocephalidae) was confirmed at several sites in the lower Oder river basin in Poland. The preferred host for this cestode species is the European eel (Anguilla anguilla), with a wide range of other fish species serving as paratenic hosts. The pumpkinseed showed a relatively high prevalence and abundance of larvae, along with several mature and gravid specimens, thereby confirming development of B. claviceps to the adult stage in an alternative host. As such, the pumpkinseed may represent an additional definitive host for this cestode, in addition to its role as a paratenic host, as previously recorded in other European regions. Our results indicate that inclusion of pumpkinseed as an additional definitive host in the cestode's life cycle, high infection of pumpkinseed with B. claviceps larvae and inclusion of pumpkinseed in the eel's diet could potentially lead to increased parasite pressure on native fish hosts. Further comparative studies or experimental testing will be required to confirm this.

• Keywords
• Aquatic invasions, Cestode, Host-parasite interaction, Oder river basin, Pumpkinseed,
• MeSH
• Anguilla MeSH
• Cestoda * growth & development   MeSH
• Fish Diseases * parasitology   MeSH
• Perciformes * parasitology   MeSH
• Life Cycle Stages MeSH
• Introduced Species MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Europe MeSH

An exhaustive literature search supplemented by a critical examination of records made it possible to present an annotated checklist of tapeworms (Cestoda) that, as adults or larvae (metacestodes), parasitize freshwater, brackish water and marine fishes, i.e. cartilaginous and bony fishes, in South America. The current knowledge of their species diversity, host associations and geographical distribution is reviewed. Taxonomic problems are discussed based on a critical evaluation of the literature and information on DNA sequences of individual taxa is provided to facilitate future taxonomic and phylogenetic studies. As expected, the current knowledge is quite uneven regarding the number of taxa and host-associations reported from the principal river basins and marine ecoregions. These differences may not only reflect the actual cestode richness but may also be due to the research effort that has been devoted to unravelling the diversity of these endoparasitic helminths in individual countries. A total of 297 valid species, 61 taxa identified to the generic level, in addition to unidentified cestodes, were recorded from 401 species of fish hosts. Among the recognized cestode orders, 13 have been recorded in South America, with the Onchoproteocephalidea displaying the highest species richness, representing c. 50% of all species diversity. The majority of records include teleost fish hosts (79%) that harbour larval and adult stages of cestodes, whereas stingrays (Myliobatiformes) exhibit the highest proportion of records (39%) among the elasmobranch hosts. Fish cestodes are ubiquitous in South America, being mostly recorded from the Warm Temperate Southeastern Pacific (WTSP; 31%) for marine hosts and the Amazon River basin (45%) for freshwater ones. The following problems were detected during the compilation of literary data: (i) unreliability of many records; (ii) poor taxonomic resolution, i.e. identification made only to the genus or even family level; (iii) doubtful host identification; and (iv) the absence of voucher specimens that would enable us to verify identification. It is thus strongly recommended to always deposit representative specimens in any type of studies, including faunal surveys and ecological studies. An analysis of the proportion of three basic types of studies, i.e. surveys, taxonomic and ecological papers, has shown a considerable increase of ecological studies over the last decade.

• Keywords
• Biodiversity, marine ecoregions, river basins, species richness, tapeworms,
• Publication type
• Journal Article MeSH

Two new species of bothriocephalidean tapeworms, Bothriocephalus australis n. sp. from the flatheads Platycephalus bassensis Cuvier (type host) and P. aurimaculatus Knapp off southern Australia and B. celineae n. sp. from a hybrid serranid Cephalopholis aurantia (Val.) x C. spiloparaea (Val.) from off New Caledonia, are described. B. australis is unique in the possession of the combination of the three characters: an elongate, obliquely situated cirrus-sac; a wide genital atrium surrounded by chromophilic cells; and a well-developed apical disc. B. celineae is typified by the presence of a low number of testes per segment (14-26), forming one or two incomplete longitudinal bands on each side of segment, and the small size of the strobila (total length 24 mm) which consists of less than 100 segments.

• MeSH
• Cestoda anatomy & histology   classification   isolation & purification   MeSH
• Chordata parasitology   MeSH
• Bass parasitology   MeSH
• Testis anatomy & histology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Australia MeSH
• New Caledonia MeSH

The tapeworm order Bothriocephalidea Kuchta, Scholz, Brabec & Bray, 2008 (Platyhelminthes: Eucestoda), which has until recently formed part of the suppressed order Pseudophyllidea, is revised. Four new genera, namely Andycestus n. g. [type- and only species A. abyssmus (Thomas, 1953) n. comb.], Plicocestus n. g. [type- and only species P. janickii (Markowski, 1971) n. comb.] (both Bothriocephalidae), Mesoechinophallus n. g. [type-species M. hyperogliphe (Tkachev, 1979) n. comb.; other species M. major (Takao, 1986) n. comb. (Echinophallidae)] and Kimocestus n. g. [type- and only species K. ceratias (Tkachev, 1979) n. comb.] (Triaenophoridae) are proposed. Parabothriocephaloides Yamaguti, 1934, Penetrocephalus Rao, 1960 and Tetracampos Wedl, 1861 are resurrected as valid genera, whereas Alloptychobothrium Yamaguti, 1968 (newly synonymised with Plicatobothrium Cable & Michaelis, 1967), Capooria Malhotra, 1985 and Coelobothrium Dollfus, 1970 (syns of Bothriocephalus Rudolphi 1808), Fissurobothrium Roitman, 1965 (syn. of Bathybothrium Lühe, 1902), Paratelemerus Gulyaev, Korotaeva & Kurochkin, 1989 (syn. of Parabothriocephaloides Yamaguti, 1934) and Tetrapapillocephalus Protasova & Mordvinova, 1986 (syn. of Oncodiscus Yamaguti, 1934) are considered to be invalid. A recently erected genus, Dactylobothrium Srivastav, Khare & Jadhav, 2006, and its type- and only species, D. choprai Srivastav, Khare & Jadhav, 2006, are considered to be unrecognisable, because their descriptions contain a number of obvious errors and also indicate that a mixture of several taxa, probably of at least two cestode orders, were studied. Parabothriocephaloides wangi nom. nov. is proposed for Parabothriocephalus psenopsis Wang, Liu & Yang, 2004 from Psenopsis anomala in China in order to avoid a secondary homonymy. All 46 genera considered to be valid are revised, with their generic diagnoses amended on the basis of a critical examination of extensive museum and newly collected specimens. Despite apparent paraphyly or polyphyly of some bothriocephalidean families, especially the Triaenophoridae, the current classification restricted to four families, proposed by Bray et al. (1994), namely the Bothriocephalidae, Echinophallidae, Philobythiidae and Triaenophoridae, is provisionally retained with slight modifications until more molecular data on most genera are available. Keys to families and genera are provided.

• MeSH
• Cestoda classification   ultrastructure   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH