Spermiogenesis and ultrastructure of mature spermatozoon of the caryophyllidean cestode Hunterella nodulosa, a parasite of suckers (Catostomidae), have been studied by transmission electron microscopy. This monozoic tapeworm is unique in its mode of attachment and represents the second North American species studied. The process of spermiogenesis of H. nodulosa follows the general pattern already described in other caryophyllideans. The most characteristic feature is the presence of a slight rotation of the flagellar bud, which seems to be a typical character of spermiogenesis in this cestode group. The mature spermatozoon of H. nodulosa is characterized by the presence of one axoneme of 9 + "1" type of the trepaxonematan flatworms surrounded by a semi-arc of cortical microtubules in its anterior extremity, parallel nucleus and cortical microtubules arranged in a parallel pattern, which corresponds to the Type III pattern of cestode spermatozoa according to Levron et al. (2010). Comparison of the present data with those available for other caryophyllideans did not reveal substantial differences, even though they belong to different families, infect different hosts (catostomid, cyprinid and siluriform fishes) and occur in distant zoogeographical regions. This indicates uniformity of the process of sperm formation and spermatozoon ultrastructure in one of the evolutionarily most ancient groups of tapeworms.
- MeSH
- Cestoda physiology ultrastructure MeSH
- Cypriniformes MeSH
- Fish Diseases epidemiology parasitology MeSH
- Spermatogenesis physiology MeSH
- Spermatozoa cytology MeSH
- Animals MeSH
- Check Tag
- Male 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
- Geographicals
- North America MeSH
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.
- MeSH
- Biological Evolution * MeSH
- Cestoda genetics MeSH
- Cestode Infections parasitology veterinary MeSH
- Host-Parasite Interactions * MeSH
- Cypriniformes parasitology MeSH
- Fish Diseases parasitology MeSH
- Genetic Speciation * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Canada MeSH
- United States MeSH
Monozoic cestodes of the recently amended genus Promonobothrium Mackiewicz, 1968 (Cestoda: Caryophyllidea), parasites of suckers (Cypriniformes: Catostomidae) in North America, are reviewed, with information on their host specificity, distribution and data on the scolex morphology of seven species studied for the first time using scanning electron microscopy (SEM). Evaluation of type and voucher specimens from museum collections and newly collected material of most species indicated the following valid nominal species: Promonobothrium minytremi Mackiewicz, 1968 (type species); P. ingens (Hunter, 1927); P. hunteri (Mackiewicz, 1963); P. ulmeri (Calentine et Mackiewicz, 1966); P. fossae (Williams, 1974) and P. mackiewiczi (Williams, 1974). Rogersus Williams, 1980 with its only species R. rogersi is transferred to Promonobothrium based on morphological and molecular data. Promonobothrium currani sp. n. and P. papiliovarium sp. n. are described from Ictiobus bubalus (Rafinesque) and Ictiobus niger (Rafinesque), and Erimyzon oblongus (Mitchill), respectively. The newly described species can be distinguished from the other congeners by the morphology of the scolex, the position of the anteriormost vitelline follicles and testes, the presence of postovarian vitelline follicles and the shape of the ovary. Molecular phylogenetic analyses of six species based on sequences of the small and large subunits of the nuclear ribosomal RNA genes (ssrDNA, lsrDNA) confirmed the monophyletic status of the genus and supported the validity of the species analysed. A key to identification of all species of Promonobothrium based on morphological characteristics is provided.
- MeSH
- Cestoda anatomy & histology classification genetics MeSH
- Species Specificity MeSH
- Phylogeny * MeSH
- Cypriniformes parasitology MeSH
- DNA, Ribosomal genetics MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- North America MeSH
The sicklefin redhorse, Moxostoma sp. (Cypriniformes: Catostomidae), is an innominate imperiled catostomid endemic to the Hiwassee and Little Tennessee river basins, which has been restricted to a few tributaries of these systems by impoundments. During collections to propagate sicklefin redhorse for reintroduction, a myxozoan, described herein, was observed infecting sicklefin redhorse in the Little Tennessee River Basin, North Carolina. Myxobolus naylori Ksepka et Bullard sp. n. infects the stratum spongiosum covering the scales of sicklefin redhorse. Myxospores of the new species differ from all congeners by the combination of having a mucous envelope, intercapsular process, and sutural markings as well as lacking an iodinophilic vacuole in the sporoplasm. A phylogenetic analysis of the 18S rDNA gene recovered the new species in a polytomy with Myxobolus marumotoi Li et Sato, 2014 and a clade comprised of species of Myxobolus Bütschli, 1882; Thelohanellus Kudo, 1933, and Dicauda Hoffman et Walker, 1973. Histological sections of infected sicklefin redhorse skin revealed myxospores within a plasmodium in the stratum spongiosum dorsal to scales, encapsulated in collagen fibres, and associated with focal erosion of scales directly beneath the plasmodium; in some instances, the scale was perforated by the plasmodium. The specificity of the new species to sicklefin redhorse may make it a useful biological tag to differentiate sicklefin redhorse from morphologically similar species. The new species is the first parasite reported from sicklefin redhorse, a species of concern to the United States Fish and Wildlife Service. No species of Myxobolus has been reported from species of Moxostoma in the Southeast United States. As it was observed that Myxobolus minutus Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise et Pote, 2016 is a primary junior homonym of Myxobolus minutus Nemeczek, 1911, we propose the replacement name Myxobolus diminutus (Rosser, Griffin, Quiniou, Alberson, Woodyard, Mischker, Greenway, Wise et Pote, 2016).
- MeSH
- Species Specificity MeSH
- Phylogeny MeSH
- Cypriniformes MeSH
- Myxobolus MeSH
- Fish Diseases epidemiology pathology MeSH
- Parasitic Diseases, Animal epidemiology parasitology MeSH
- Prevalence MeSH
- Rivers MeSH
- DNA, Ribosomal MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- North Carolina MeSH
External and internal morphological characters of the holotype of Enobarbus maculatus were examined and compared with those of other cobitid species to verify whether Enobarbus is a distinct genus. Analyses of radiographs demonstrated that the neural spines and the pterygiophores of the dorsal fin are of irregular shape, often doubled, reduced or bent. The holotype of E. maculatus bears an ossified structure on the last pectoral-fin ray, a structure otherwise known only from males of the genus Lepidocephalichthys. In Lepidocephalichthys, the shape of the ossified structure is species-specific, and the structure of Enobarbus is very similar to that of Lepidocephalichthys thermalis, the only other known species of the family Cobitidae occurring at the type locality of Enobarbus. Furthermore, the cranial and the axial skeleton of E. maculatus is similar to that of L. thermalis, except for the pterygiophores and the neural spines, that are strongly malformed in Enobarbus. In general, the results presented here show that the genus Enobarbus shares the most important characters (thickening of last two pectoral-fin rays in males, structure of swimbladder capsule, shape of neurocranium and suborbital spine) with Lepidocephalichthys and that its long dorsal fin is correlated with strong malformations of the vertebral column and the fin ray insertions. Consequently, the only known specimen of Enobarbus is most likely a teratological male of L. thermalis, and Enobarbus is a junior synonym of Lepidocephalichthys.
- MeSH
- Biometry MeSH
- Skeleton MeSH
- Cypriniformes anatomy & histology classification MeSH
- Animals MeSH
- Check Tag
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Comparative Study MeSH
Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction.
- MeSH
- Biological Evolution * MeSH
- Diploidy * MeSH
- Karyotype * MeSH
- Cypriniformes genetics MeSH
- Reproduction, Asexual genetics MeSH
- Triploidy * MeSH
- Animals MeSH
- Check Tag
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Thermal requirements of larval weatherfish Misgurnus fossilis were investigated in terms of growth, survival and aerobic performance. Growth and survival of M. fossilis larvae acclimated to five temperatures (11, 15, 19, 23 and 27° C) were measured over 25 days. In the upper temperature treatments (19, 23 and 27° C), survival of larvae was stable throughout the entire rearing period (>75%), whereas 11 and 15° C resulted in severe declines in survival (to <10%). Growth of larvae (expressed as dry mass and total length) was highest at 19 and 23° C, but significantly decreased at 27° C. Routine metabolic rate of 3 days post-hatch larvae was estimated as oxygen consumption rate (ṀO2 ) during acute exposure (30 min to 1 h) to seven temperatures (11, 15, 19, 23, 27, 31 and 35° C). Larval oxygen uptake increased with each consecutive temperature step from 11 to 27° C, until a plateau was reached at temperatures >27° C. All larvae of the 35° C regime, however, died within the ṀO2 measurement period. M. fossilis larvae show greater than expected tolerance of high temperatures. On the other hand, low temperatures that are within the range of likely habitat conditions are critical because they might lead to high mortality rates when larvae are exposed over periods >10 days. These findings help to improve rearing conditions and to identify suitable waters for stocking and thus support the management of re-introduction activities for endangered M. fossilis.
- MeSH
- Larva growth & development MeSH
- Cypriniformes growth & development physiology MeSH
- Oxygen Consumption * MeSH
- Temperature * MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
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.
- MeSH
- Biological Evolution MeSH
- Cestoda anatomy & histology classification ultrastructure MeSH
- Cypriniformes parasitology MeSH
- Microscopy, Electron, Scanning MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Publication type
- Journal Article MeSH
- MeSH
- Nematoda anatomy & histology isolation & purification MeSH
- Larva MeSH
- Cypriniformes parasitology MeSH
- Fishes parasitology MeSH
- Animals MeSH
- Check Tag
- Animals MeSH
- Geographicals
- Texas MeSH
Leptobotia micra, new species, is described from the upper Li River (Pearl River basin) around Guilin in Guangxi province, southern China. The new species is evidently the smallest species of Leptobotia, with females of 45‒46 mm SL bearing oocytes. It can be distinguished from all other species of Leptobotia by a combination of the following characters: no dark bars or dorsal saddles on body, a row of white dots along dorsal midline, 4+34 vertebrae, a predorsal distance of 58.1‒59.0% SL, eye diameter 1.8‒2.0 % SL, pelvic fins not reaching anus, an emarginated caudal fin (length of median rays 1.3‒1.4 times in length of lower lobe) and the anus positioned distinctly closer to anal-fin origin than to pelvic-fin base.
