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Digesta were collected from the intestines of seven species of bottom-feeding fish to better understand the role of incidental ingestion of sediment in exposing fish to inorganic contaminants. A composite sediment tracer variable, based on concentrations of Co, Cr, Ni, Ti, V, and Y in digesta and in sediment, was calculated to estimate sediment content of digesta. Concentration factors (mg/kg in digesta divided by mg/kg in sediment) of eight elements of interest were linearly regressed on this tracer variable. The relative importance of sediment ingestion to oral exposure was quantified. Zinc, Cd, and Cu were ingested mainly from sediment-free food. Arsenic, Cr, Ni, Al, and Pb, in contrast, were ingested mainly from sediment. As an example, 93% of the Ni in digesta from a brown bullhead (Ameiurus nebulosus) was from sediment and only 7% from food. Regressions of Al and Pb in digesta of suckers (Catostomidae) suggested an additional oral source, possibly from oxides coating biotic or abiotic surfaces. Overall, concentrations of 12 of 21 elements studied were positively correlated with sediment content (p < 0.005). Including sediment ingestion as a pathway for bottom-feeding fish is essential for accurately estimating exposures in toxicological studies. Environ Toxicol Chem 2024;43:1036-1046. Published 2024. This article is a U.S. Government work and is in the public domain in the USA., (Published 2024. This article is a U.S. Government work and is in the public domain in the USA.)

Ribosomal DNA sequences are currently available for 32 morphologically recognized species of Dactylogyrus parasitizing Nearctic cypriniforms, but only 16 of them are assigned to nominal species. Herein, morphological data on 28 of the 32 species are provided, together with comments on their phylogenetic relationships in the context of the morphology of taxonomically important structures. Seven new species of Dactylogyrus are described from five species of leuciscids and one species of catostomids, as follows: D. aduncus n. sp. from Campostoma spadiceum, D. cloutmani n. sp. from Luxilus chrysocephalus isolepis, D. cornifrons n. sp. from Cyprinella venusta, D. fimbratus n. sp. from Rhinichthys cataractae, D. mcallisteri n. sp. from Semotilus atromaculatus, and D. chieni n. sp. and D. haneki n. sp. from Hypentelium nigricans. Four previously described species of Dactylogyrus, D. atromaculatus from S. atromaculatus, D. eos from C. neogaeus, D. parvicirrus from Notemigonus crysoleucas and D. perlus from L. c. isolepis, are redescribed and/or figured. As for the remaining 17 species, only the male copulatory organs (MCOs) taken from the respective hologenophores are illustrated. On the basis of phylogenetic analyses, two main clades of Nearctic Dactylogyrus were recognized and supported by the different morphology of the MCO. The first one included 22 strictly Nearctic species sharing the same MCO type with Dactylogyrus spp. parasitizing cyprinids likely of Asian origin. The second clade encompassed Dactylogyrus spp. with diverse MCO morphology and was placed in the sister position to Dactylogyrus spp. parasitizing European leuciscids and North-West African cyprinids., (© E. Řehulková et al., published by EDP Sciences, 2023.)

The relationship between June sucker ( Chasmistes liorus , Jordan, 1878) and Utah sucker ( Catostomus ardens , Jordan & Gilbert, 1881) has been a matter of controversy since the mid 1900s. Chasmistes liorus is endemic to Utah Lake, UT and has a subterminal mouth adapted for pelagic feeding. Catostomus ardens is widely distributed throughout the Bonneville Basin and Upper Snake River Basin and has a ventral mouth adapted for benthic feeding. Chasmistes has been recognized as a separate ancient genus. Despite being morphologically distinct, no study has successfully identified residual genetic markers that separate these species. Of these studies, several have used a subset of mitochondrial genes, but no study has analyzed the complete mitochondrial genomes (mitogenomes) of these suckers (Pisces: Catostomidae). To further explore the genetic relationships between these species, we report the complete mitogenomes of Chasmistes liorus and Catostomus ardens . DNA was sequenced using an Illumina HiSeq 2500 system and mitogenomes were assembled and annotated using Geneious v. 2021.2 and MitoAnnotator, respectively. The mitogenomes of Chasmistes liorus and Catostomus ardens are both 16,623 bp and are ∼0.072% divergent. We examine the phylogenetic relationship between Chasmistes liorus and Catostomus ardens using 33 mitogenomes, representing 16 species, from Catostomidae. Our data suggest that Chasmistes liorus is sister to Catostomus ardens . Additional samples from multiple localities and/or cohorts of these species will allow us to better resolve the complicated phylogenetic relationships between these species., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

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., (© D. Uhrovič et al., published by EDP Sciences, 2022.)

Identification of introduced species can be important to understanding ecological systems and meeting conservation and management goals, but the process can be surprisingly challenging. The Klamath smallscale sucker Catostomus rimiculus seems likely to be native to the Smith River because the drainage separates two basins believed to be within the fish's native range, the Rogue and Klamath rivers. Further, C. rimiculus is broadly distributed in the Smith River, and the indigenous Dee-ni' People of the Smith River have a unique word for sucker. Nonetheless, a historical survey of fishes that described C. rimiculus from the Rogue and Klamath rivers did not include C. rimiculus among the fishes of the Smith River. To determine whether the genetic structure of the Smith River C. rimiculus reflects expectations for a native sucker population, the authors of this study examined variation in microsatellite and mitochondrial genetic markers from the Smith River and surrounding drainages. The genetic analyses revealed a pattern consistent with extreme founder effects in Smith River C. rimiculus, as would be expected from a single introduction of six or fewer effective individuals. The sharing of a high-frequency haplotype between the Smith River and Klamath River that is not detected in the Rogue River suggests the Klamath River as the likely source for the introduction. The findings highlight that local-scale introductions can be easily overlooked because the newly established populations can appear to be parts of contiguous natural distributions., (© 2021 Fisheries Society of the British Isles.)

The first survey of caryophyllidean tapeworms parasitising catostomid and cyprinid fish in Mexico is provided, including new host and geographical records. Isoglaridacris brevicollis n. sp. is described from the Nazas sucker, Catostomus nebuliferus Garman (type host), in Durango, C. bernardini Girard in Sonora, and Moxostoma austrinum Bean (Cypriniformes: Catostomidae) in Jalisco. The new species differs from congeners mainly in the shape of the scolex, which is rounded, and by the absence of a defined neck (distinct, often long in other congeners). Pseudoglaridacris confusa found in Ictiobus meridionalis (also a member of the family Catostomidae) from Oaxaca and Veracruz represents the southern-most report of species of this Nearctic genus. Three morphotypes of the holarctic Archigetes Leuckart, 1878 were found in two leuciscid fishes ( Notropis caliensis and N. nazas ) and in silverside Chirostoma sp. (Atherinidae). It is the first record of any caryophyllidean in atheriniform fish. The first record of Khawia japonensis (Yamaguti, 1934) (syn. K. iowensis Calentine et Ulmer, 1961), a parasite of common carp ( Cyprinus carpio L.), in Mexico represents another evidence of its invasive potential. The caryophyllidean fauna of Mexican freshwater fish is depauperate compared to that in the United States and Canada, which seems to be related to a much lower number of species of suckers (Catostomidae) occurring in Mexico, possibly also to the lower number of fish in the population., Competing Interests: There is no conflict of interest in the submitted manuscript entitled “Caryophyllidean tapeworms (Cestoda), Nearctic parasites of fish in Mexico, including description of a new species of Isoglaridacris and the first report of Khawia japonensis, an invasive parasite of common carp (Cyprinus carpio).”, (© 2021 The Authors.)

A comparative study of the scoleces of monozoic tapeworms (Cestoda: Caryophyllidea), parasites of catostomid and cyprinid fishes (Teleostei: Cypriniformes) in the Nearctic Region, was carried out using light and scanning electron microscopy. Scoleces of 22 genera of North American caryophyllideans were characterised and their importance for taxonomy, classification and phylogenetic studies was critically reviewed. Nearctic genera exhibit a much higher variation in the shape and form of scoleces compared with taxa in other biogeographical regions. The following basic scolex types can be recognised in Nearctic caryophyllideans: monobothriate (Promonobothrium Mackiewicz, 1968), loculotruncate (Promonobothrium, Dieffluvium Williams, 1978), bothrioloculodiscate (Archigetes Leuckart, 1878, Janiszewskella Mackiewicz et Deutsch, 1976, Penarchigetes Mackiewicz, 1969, Pseudoglaridacris Oros, Uhrovič et Scholz, 2018), fixomegabothriate (Capingens Hunter, 1927), bulbate and bulboacuminate (Atractolytocestus Anthony, 1958), cuneiloculate (Hypocaryophyllaeus Hunter, 1927, Rowardleus Mackiewicz et Deutsch, 1976, Spartoides Hunter, 1929), biacetabulate, bulboloculate, bothrioloculodiscate (Biacetabulum Hunter, 1927), tholate (Hunterella Mackiewicz et McCrae, 1962), cuneifimbriate (Khawia Hsü, 1935), cuneiform (Calentinella Mackiewicz, 1974, Caryophyllaeides Nybelin, 1922, Edlintonia Mackiewicz, 1970), hastate (Pseudolytocestus Hunter, 1929), loculotholate (Bialovarium Fischthal, 1953, Pliovitellaria Fischthal, 1951), and cuneiformoloculate (Glaridacris Cooper, 1920, Isoglaridacris Mackiewicz, 1965). The same type of scolex may be shared by species of different genera or families and species of the same genus can have a scolex of conspicuously different morphology, e.g. in Promonobothrium. Scolex morphology may be therefore of limited use in generic designation.

A new species of monogenean, Dactylogyrus pisolabrae n. sp., was found parasitizing the gills of the Pealip Redhorse, Moxostoma pisolabrum, from Oklahoma. Dactylogyrus pisolabrae is morphologically similar to Dactylogyrus apos, Dactylogyrus atripinnei, Dactylogyrus duquesnei, and Dactylogyrus niger, all parasitizing other species of suckers, by possessing a robust, sickle-shaped male copulatory organ, but differs from these and all other species of North American Dactylogyrus by possessing 2 unique wing-like projections opposite each other on the proximal portion of the accessory piece. Dactylogyrus pisolabrae represents the first monogenean reported from the Pealip Redhorse.

Catostomidae ("suckers") is a diverse (76 species) and broadly distributed family of Holarctic freshwater fishes with a rich fossil record and a considerable number (∼35%) of threatened and imperiled species. We integrate DNA sequences (three mitochondrial genes, three nuclear genes), morphological data, and fossil information to infer sucker phylogenetic relationships and divergence times using Bayesian "total-evidence" methods, and then test hypotheses about the temporal diversification of the group. Our analyses resolved many nodes within subfamilies and clarified Catostominae relationships to be of the form ((Thoburniini, Moxostomatini), (Erimyzonini, Catostomini)). Patterns of subfamily relationships were incongruent, but mainly supported two placements of the Myxocyprininae; distinguishing these using Bayes factors lent strongest support to a model with Myxocyprininae sister to all remaining sucker lineages. We improved our Bayesian total-evidence dating analysis by excluding problematic characters, using a clock-partitioning scheme identified by Bayesian model selection, and employing a fossilized birth-death tree prior accommodating morphological data and fossils. The resulting chronogram showed that suckers evolved since the Late Cretaceous-Eocene, and that the Catostomini and Moxostomatini clades have accumulated species diversity since the early to mid-Miocene. These results agree with the fossil record and confirm previous hypotheses about dates for the origins of Catostomide and catostomine diversification, but reject previous molecular hypotheses about the timing of divergence of ictiobines, and between Asian-North American lineages. Overall, our findings from a synthesis of multiple data types enhance understanding of the phylogenetic relationships, taxonomic classification, and temporal diversification of suckers, while also highlighting practical methods for improving Bayesian divergence dating models by coupling phylogenetic informativeness profiling with relaxed-clock partitioning., Competing Interests: The authors declare that they have no competing interests.

The complete mitochondrial genome of Ictiobus cyprinellus was first determined by a polymerase chain reaction-based sequencing method in this study. The mitochondria was 16,611 bp in length, including 13 protein genes, 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes and 1 control region. All genes were encoded on the heavy strain except for ND6 and eight tRNA genes. The gene arrangement of I. cyprinellus was similar to those found in the other Catostomidae species. Base composition of the heavy strain was A (29.40%), T (24.86%), C (27.96%), G (17.78%) and with A + T bias of 54.26%.