The caryophyllidean tapeworms (Cestoda) of the genus Isoglaridacris Mackiewicz, 1965 are revised on the basis of the study of type specimens and newly collected material from suckers (Cypriniformes: Catostomidae) in North America. Molecular data reveal the presence of 14 lineages, each representing a separate species. An overview of all nominal species is provided, with updated information on their hosts, distribution and phylogenetic relationships. Isoglaridacris multivitellaria Amin, 1976 is excluded from Isoglaridacris, but its generic affiliation remains unclear, and it is considered incertae sedis. Homeomorpha mackiewiczi Dutton et Barger, 2014 from Minytrema melanops is transferred to Isoglaridacris as I. mackiewiczi (Dutton et Barger, 2014) new combination. Based on molecular and morphological data, four new species are described: Isoglaricris mattisi n. sp. from Moxostoma collapsum in South Carolina, USA, I. mcallisteri n. sp. from Erimyzon claviformis in Arkansas and Oklahoma, USA, I. mexicanus n. sp. from Moxostoma cf. austrinum in Chihuahua, Mexico, and I. floriani n. sp. from M. macrolepidotum in South Carolina. A key to the identification of all 16 valid species is provided. Isoglaridacris species exhibit strict host specificity, with most species parasitising only a single host species (strict specialists), while a few species occur in more than one species within the same host genus (congeneric specialists). The distribution range of Isoglaridacris species includes southern Canada, the United States and northwestern (nearctic) Mexico.

• Keywords
• Fish, Nearctic region, Phylogenetic relationships, Revision, Species diversity, Taxonomy,
• MeSH
• Cestoda * genetics   classification   anatomy & histology   MeSH
• Cestode Infections * parasitology   veterinary   MeSH
• Phylogeny * MeSH
• Cypriniformes * parasitology   MeSH
• Fish Diseases * parasitology   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• North America MeSH

Freshwater ecosystems in Lithuania are threatened by the introduction of invasive fish species including Neogobius fluviatilis, N. melanostomus, Perccottus glenii, and Pseudorasbora parva. Data on helminth parasites of these fishes have not been comprehensively studied, with only two reports on parasites of N. melanostomus from the Curonian Lagoon and Baltic Sea, Lithuania. We examined 278 fish individuals representing 4 invasive species from 13 waterbodies. Using morphological and molecular analyses, we identified 29 helminth taxa representing 15 digenean trematodes, 6 nematodes, 4 cestodes, 2 acanthocephalans, and 2 monogeneans. With 18 species, N. fluviatilis had the highest helminth diversity, followed by N. melanostomus (11 species) and Ps. parva (8 species). Perccottus glenii was found to be free from helminth infection. The availability of historical information on the native fish parasites in Lithuania allowed us to conclude that out of the 29 recorded species, invasive fish serve as hosts for 22 local fish helminth species, while 7 helminth species have been reported exclusively in invasive fish. Based on newly obtained and previously published data, a total of 34 helminth species parasitise invasive fish in Lithuania, of which 30 use these fish as intermediate or paratenic hosts.

• Keywords
• Baltic freshwater ecosystems, Neogobius spp., Perccottus glenii, Pseudorasbora parva, aquatic invasion, morphological and molecular identification,
• Publication type
• Journal Article 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