Ceratomyxa aegyptiaca n. sp. (Myxozoa: Myxosporea) from the gall-bladder of Solea aegyptiaca Chabanaud (Pleuronectiformes: Soleidae) in a Tunisian coastal lagoon

A new marine myxosporean species, Ceratomyxa aegyptiaca n. sp. is described from the gall-bladder of Solea aegyptiaca Chabanaud collected from the Ghar El Melh Lagoon in northeastern Tunisia. Mature spores are elongate and crescent-shaped, measuring 8-11?μm in length and 48-58?μm in width. The polar capsules are spherical, 3.2-4?μm in diameter and equal in size. Trophozoites are polysporous and float free in the bile or are attached on the epithelium of the gall-bladder. Morphological data and molecular analysis based on 18S rDNA sequences are provided. The 18S rDNA of C. aegyptiaca is readily distinguishable from that of other myxozoan species, as the genetically most similar myxozoan parasite, C. seriolae Yokoyama & Fukuda, 2001 (AB530265) collected from Seriola quinqueradiata Temminck & Schlegel in Japanese waters, shares with it only 67.5% identical nucleotides over a 1,680-bp long fragment of 18S rDNA.     

Myxidium macrocheili n. sp. (Cnidospora: Myxidiidae) from the Largescale Sucker Catostomus macrocheilus Girard,and a Synopsis of the Myxidium of North American Freshwater Vertebrates*

SYNOPSIS. Myxidium macrocheili n. sp. is described from the gall bladder, bile and pancreatic ducts of Catostomus macrocheilus Girard (largescale sucker) in western Montana. This parasite is markedly host specific; the trophozoite is nonmotile, polysporous, spheroidal, elongated or irregular, often arched and rolled at the edges, and up to 2.5 mm in greatest length; the ecto- and endoplasm are distinct; the sporonts are disporoblastic. The bipolar spore is longitudinally striated, usually ellipsoidal in front view, slightly S-shaped in side view, and averages 11.7 × 6.6 × 6.3 μ; the suture line and ridge are distinct; the polar filaments are coiled 4–6 times. An illustrated synopsis and a key of the 19 species and 10 unnamed forms of Myxidium of North American freshwater vertebrates are presented. At present members of the genus are known to infect fishes, amphibians and a single species of reptile on this continent.     

Comparative trophic impacts of two globally invasive cyprinid fishes reveal species‐specific invasion consequences for a threatened native fish

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Morphology and molecular phylogeny of Hoferellus jutubensis n. sp. (Cnidaria: Myxozoa) found parasitising Ageneiosus inermis (Siluriformes: Auchenipteridae), in the Brazilian Amazon region

The present study describes Hoferellus jutubensis n. sp., a myxozoan parasite found in the urinary bladder of the driftwood catfish Ageneiosus inermis, captured on Jutuba Island in the state of Pará, northern Brazil. A total of 30 A. inermis specimens were examined, of which 26 (86.7%) had myxospores and polysporic plasmodia of varying shapes and sizes dispersed in the lumen of the urinary bladder, either floating freely or attached to the epithelium. In the apical view, the myxospores of Hoferellus jutubensis n. sp. are rounded, 6.1 ± 0.2 (5.7–6.3) μm long and 5.5 ± 0.3 (5.2–6.0) μm wide, with two sub-spherical polar capsules, equal in size and shape, 2.5 ± 0.2 (2.3–2.7) μm long and 1.7 ± 0.2 (1.4–2.2) μm wide. The phylogenetic analysis of a partial sequence of the SSU rDNA gene, indicated that the new species is the sister taxon of Hoferellus azevedoi, with these two species forming a Brazilian lineage of Hoferellus. The comparison of the morphological and molecular data with those of the existing members of the genus confirmed the species status of Hoferellus jutubensis n. sp., which adds one further Hoferellus taxon to the known myxosporean diversity of the Amazon basin.     

Henneguya polarislonga n. sp. (Cnidaria: Myxosporea) parasitizing Astyanax lacustris (Lütken, 1875) with an insight on its life cycle

Henneguya polarislonga n. sp. is described from the gills of Astyanax lacustris (Lütken, 1875) (Characiformes, Characidae) from streams of the Middle Paranapanema River, Upper Paraná River basin, in the São Paulo State, Brazil. The proposed new species is supported by a combination of morphological and molecular characterization (partial fragment of the SSU rDNA). Thirty specimens of A. lacustris were analyzed and myxospores were found in the gill lamellae of one specimen (Prevalence = 3.3%). Henneguya polarislonga n. sp. was morphometrically and genetically distinct from other Henneguya spp. previously described in Astyanax spp., mainly differing in the total length and caudal appendages length of the mature myxospores. Comparative analysis of the SSU rDNA sequences revealed that Seisactinomyxon-type actinospores previously reported parasitizing oligochaetes are developmental stages of the life cycle of Henneguya polarislonga n. sp. (similarity of 99.9%). This is the first time that an actinospore and a myxospore are correlated through molecular analysis in Brazil, contributing to the knowledge of the myxozoan ecology and biodiversity.     

Involvement of Manayunkia speciosa (Annelida: Polychaeta: Sabellidae) in the life cycle of Parvicapsula minibicornis, a myxozoan parasite of Pacific salmon

A coelomic myxozoan infection was detected in freshwater polychaetes, Manayunkia speciosa from the Klamath River, Oregon/California, a site enzootic for the myxozoan parasites Ceratomyxa shasta and Parvicapsula minibicornis. The tetractinomyxon type actinospores had a near-spherical spore body 7.9 x 7.1 microm, with 3 spherical, protruding polar capsules, no valve cell processes, and a binucleate sporoplasm. Parvicapsula minibicornis-specific primers Parvi1f and Parvi2r amplified DNA from infected polychaetes in a polymerase chain reaction (PCR) assay. The small subunit 18S rRNA gene of the spores was sequenced (GenBank DQ231038) and was a 99.7% match with the sequence for P. minibicornis myxospore stage in GenBank (AF201375). Chinook salmon (Oncorhynchus tshawytscha) exposed to a dose of 1,000 actinospores per fish tested PCR positive for P. minibicornis at 14 wk postinfection and presporogonic stages were detected in the kidney tubules by histology at 20 wk. This life cycle is 1 of only about 30 known from more than 1,350 myxozoan species, and only the second known from a freshwater polychaete.     

Parasite spillover: indirect effects of invasive Burmese pythons

Identification of the origin of parasites of nonindigenous species (NIS) can be complex. NIS may introduce parasites from their native range and acquire parasites from within their invaded range. Determination of whether parasites are non‐native or native can be complicated when parasite genera occur within both the NIS’ native range and its introduced range. We explored potential for spillover and spillback of lung parasites infecting Burmese pythons (Python bivittatus) in their invasive range (Florida). We collected 498 indigenous snakes of 26 species and 805 Burmese pythons during 2004–2016 and examined them for lung parasites. We used morphology to identify three genera of pentastome parasites, Raillietiella, a cosmopolitan form, and Porocephalus and Kiricephalus, both New World forms. We sequenced these parasites at one mitochondrial and one nuclear locus and showed that each genus is represented by a single species, R. orientalis, P. crotali, and K. coarctatus. Pythons are host to R. orientalis and P. crotali, but not K. coarctatus; native snakes are host to all three species. Sequence data show that pythons introduced R. orientalis to North America, where this parasite now infects native snakes. Additionally, our data suggest that pythons are competent hosts to P. crotali, a widespread parasite native to North and South America that was previously hypothesized to infect only viperid snakes. Our results indicate invasive Burmese pythons have affected parasite‐host dynamics of native snakes in ways that are consistent with parasite spillover and demonstrate the potential for indirect effects during invasions. Additionally, we show that pythons have acquired a parasite native to their introduced range, which is the initial condition necessary for parasite spillback.     

Myxidium leei (Myxozoa) infections in aquarium-reared Mediterranean fish species.

An episode of parasitic enteritis causing trickling mortalities at an exhibition aquarium reproducing Mediterranean ecosystems was found to be caused by the myxozoan parasite Myxidium leei Diamant, Lom & Dykova 1994. The myxozoan was recorded in 25 different fish species belonging to 16 Genera, 10 Families and 4 Orders. It was mainly detected in the intestine of affected fish, and was responsible for severe chronic enteritis. The parasite was probably introduced into the facilities with infected wild fish, and transmitted directly from fish to fish by cohabitation, transfer of infected material and necrophagia. Fish belonging to the Families Labridae and Blenniidae appeared as most susceptible, and the incidence of infections in members of the Sparidae was low. This study significantly widens the host spectrum for this virulent parasite and now includes many ubiquitous coastal Mediterranean species. Wild fish may have a significant role in the transmission of myxidiosis of cultured sparid fish.     

Species richness and similarity of metazoan parasite communities in three species of leatherjacket (Oligoplites: Pisces: Carangidae) from the Pacific coast of Mexico

Species richness and similarity in metazoan parasite communities of fishes can be influenced by several biotic (age, body size, vagility, feeding and social behavior, among others), and local abiotic (temperature, salinity, etc.) factors. The parasite communities of three species of Oligoplites, marine fishes from the Pacific coast of Mexico, were quantified and analyzed. Four hundred sixty‐eight leatherjackets (O. altus, n=94; O. saurus, n=260; and O. refulgens, n=114) were collected from February 2016 to June 2017 from five locations. Twenty‐eight species of metazoan parasites were recovered and identified: four species of Monogenea (adults), nine of Digenea (seven adults and two metacercariae); two of Cestoda (larvae); four of Nematoda (two adults and two larvae); four of Acanthocephala (two adults, one juvenile, and one cystacanth); four of Copepoda; and one Pentastomida (larvae). At the component community level, species richness ranged from 9 in O. saurus to 19 in O. altus. Different species of helminth dominated the component communities of each species of host. Community composition and species richness of parasites differed among the three species of host, locations, and sampling years. Host feeding behavior, body size, and vagility had the most influence on these differences.     

Distance decay of similarity among parasite communities of three marine invertebrate hosts

The similarity in species composition between two communities generally decays as a function of increasing distance between them. Parasite communities in vertebrate definitive hosts follow this pattern but the respective relationship in intermediate invertebrate hosts of parasites with complex life cycles is unknown. In intermediate hosts, parasite communities are affected not only by the varying vagility of their definitive hosts (dispersing infective propagules) but also by the necessary coincidence of all their hosts in environmentally suitable localities. As intermediate hosts often hardly move they do not contribute to parasite dispersal. Hence, their parasite assemblages may decrease faster in similarity with increasing distance than those in highly mobile vertebrate definitive hosts. We use published field survey data to investigate distance decay of similarity in trematode communities from three prominent coastal molluscs of the Eastern North-Atlantic: the gastropods Littorina littorea and Hydrobia ulvae, and the bivalve Cerastoderma edule. We found that the similarity of trematode communities in all three hosts decayed with distance, independently of local sampling effort, and whether or not the parasites used the mollusc as first or second intermediate host in their life cycle. In H. ulvae, the halving distance (i.e. the distance that halves the similarity from its initial similarity at 1 km distance) for the trematode species using birds as definitive hosts was approximately two to three times larger than for species using fish. The initial similarities (estimated at 1 km distance) among trematode communities were relatively higher, whereas mean halving distances were lower, compared to published values for parasite communities in vertebrate hosts. We conclude that the vagility of definitive hosts accounts for a high similarity at the local scale, while the strong decay of similarity across regions is a consequence of the low probability that all necessary hosts and suitable environmental conditions coincide on a large scale.     

Integrative Approach for the Reliable Detection and Specific Identification of the Microsporidium Loma morhua in Atlantic Cod (Gadus morhua)

Microsporidia are fungal parasites that infect diverse invertebrate and vertebrate hosts. Finfish aquaculture supports epizootics due to high host density and the high biotic potential of these parasites. Reliable methods for parasite detection and identification are a necessary precursor to empirical assessment of strategies to mitigate the effects of these pathogens during aquaculture. We developed an integrative approach to detect and identify Loma morhua infecting Atlantic cod. We show that the spleen is more reliable than the commonly presumed gills as best organ for parasite detection in spite of substantial morphological plasticity in xenoma complexes. We developed rDNA primers with 100% sensitivity in detecting L. morhua and with utility in distinguishing some congeneric Loma species. ITS sequencing is necessary to distinguish L. morhua from other congeneric microsporidia due to intraspecific nucleotide variation. 64% of L. morhua ITS variants from Atlantic cod have a 9‐nucleotide motif that distinguishes it from Loma spp. infecting non‐Gadus hosts. The remaining 36% of ITS variants from Atlantic cod are distinguished from currently represented Loma spp., particularly those infecting Gadus hosts, based on a 14‐nucleotide motif. This research approach is amenable to developing templates in support of reliable detection and identification of other microsporidian parasites in fishes.     

Taxonomy,phylogeny and host-parasite interaction of two novel Myxobolus species infecting Brycon orthotaenia from the São Francisco River,Brazil

Two new Myxobolus species were described infecting Brycon orthotaenia from the São Francisco River, in the state of Minas Gerais, Brazil. From a total of 39 B. orthotaenia collected, two specimens (5.1%) exhibited infection of the ovary and 12 specimens (30.8%) displayed infection of the liver. The plasmodia of both Myxobolus species were white and spherical measuring around 1 mm in length. The plasmodium found in the ovary showed mature myxospores, which were oval shaped from the frontal view and measured 9.2–11.0 (9.8 ± 0.4) μm in length, 5.9–6.9 (6.5 ± 0.3) μm in width and 4.6–5 (4.9 ± 0.1) μm in diameter. The two polar capsules were the same size and measured 3.9–6.2 (4.7 ± 0.5) μm in length and 1.8–2.4 (2.1 ± 0.2) μm in width. The polar tubules had 9 coils. The plasmodium found in the liver showed mature myxospores which were ellipsoidal in shape from the frontal view and measured 10.0–11.4 (10.7 ± 0.5) μm in length, 7.3–8.6 (8.1 ± 0.4) μm in width and 5.3–7.0 (6.8 ± 0.4) μm in diameter. The two polar capsules were the same size and measured 4.2–5.4 (4.9 ± 0.3) μm in length and 1.9–2.9 (2.7 ± 0.3) μm in width. The polar tubules had 8 coils. Ultrastructural analysis revealed an asynchronous sporogenesis process, with young developmental myxospore stages more often found in the periphery of the plasmodium and mature myxospores in the centre of the plasmodium. The plasmodial wall was formed by a single membrane which was not surrounded by a layer of host tissue. A thick layer of fibrous material was found in the peripheral ectoplasm close to the plasmodial wall of the plasmodium found in the ovary. Phylogenetic analysis based on the small-subunit ribosomal DNA – ssrDNA sequences and using the closest myxozoan sequences to each one of the species studied here based on previous GenBank data and Henneguya/Myxobolus/Thelohanellus species parasitizing fish from South American, revealed that the new species are grouped in a subclade together with other Myxobolus species parasitizing bryconid hosts.     

Mantoniella beaufortii and Mantoniella baffinensis sp. nov. (Mamiellales,Mamiellophyceae), two new green algal species from the high arctic1

Members of the class Mamiellophyceae comprise species that can dominate picophytoplankton diversity in polar waters. Yet, polar species are often morphologically indistinguishable from temperate species, although clearly separated by molecular features. Here we examine four Mamiellophyceae strains from the Canadian Arctic. The 18S rRNA and Internal Transcribed Spacer 2 (ITS2) gene phylogeny place these strains within the family Mamiellaceae (Mamiellales, Mamiellophyceae) in two separate clades of the genus Mantoniella. ITS2 synapomorphies support their placement as two new species, Mantoniella beaufortii and Mantoniella baffinensis. Both species have round green cells with diameter between 3 and 5 μm, one long flagellum and a short flagellum (~1 μm) and are covered by spiderweb-like scales, making both species similar to other Mantoniella species. Morphologically, M. beaufortii and M. baffinensis are most similar to the cosmopolitan M. squamata with only minor differences in scale structure distinguishing them. Screening of global marine metabarcoding data sets indicates M. beaufortii has only been recorded in seawater and sea ice samples from the Arctic, while no environmental barcode matches M. baffinensis. Like other Mamiellophyceae genera that have distinct polar and temperate species, the polar distribution of these new species suggests they are cold or ice-adapted Mantoniella species.     

Description and development of Auerbachia ignobili n. sp. (Cnidaria: Myxosporea: Bivalvulida) from the giant trevally,Caranx ignobilis (Forsskål, 1775) from Indian waters

The present study describes a new species of myxosporean, Auerbachia ignobili n. sp., infecting the hepatic bile ducts of Caranx ignobilis (Forsskål, 1775). Myxospores are club-shaped with a broad anterior region and a narrow, slightly curved and blunt caudal extension, measuring 17.4 ± 1.5 μm in length and 7.5 ± 7.4 μm in width. Shell valves asymmetrical, with a faint suture line, and enclosed a single, elongate-elliptical polar capsule with a ribbon-like polar filament, arranged in 5–6 coils. Developmental stages included early and late presporogonic stages, pansporoblast, and sporogonic stages with monosporic and disporic plasmodia. A. ignobili n. sp. differs from the other described species of Auerbachia in the shape and dimensions of the myxospores and polar capsules. The molecular analysis generated ∼1400 bp long SSU rDNA sequences and the present species exhibited a maximum similarity 94.04–94.91% with A. chakravartyi. Genetic distance analysis indicated the lowest interspecies divergence of 4.4% with A. chakravartyi. In phylogenetic analysis, A. ignobili n. sp. was positioned independently with a high bootstrap value (1/100) and appeared as sister to A. maamouni and A. chakravartyi. Fluorescent in situ hybridization and histology indicates that the parasite develops within the hepatic bile ducts. Histological studies did not reveal any pathological changes. Considering the morphological, morphometric, molecular, and phylogenetic differences coupled with the differences in host and geographic locations, the present myxosporean is treated as a new species and named A. ignobili n. sp.     

Molecular data and phylogenetic analysis of Myxobolus pseudonobilis n. sp. infecting the gill filaments of silver carp,Hypophthalmichthys molitrix Valenciennes, 1844

In the present study, we combined morphological and phylogenetic methods to characterize Myxobolus pseudonobilis n. sp. infecting Hypophthalmichthys molitrix Valenciennes, 1844 from Chongqing, China. The morphology and molecular characteristics of M. pseudonobilis n. sp. were distinct from those of other previously described Myxobolus species. Mature myxospores were ovoid in frontal view with spore dimensions of 10.0 ± 0.4 (9.3–10.9) μm in length and 8.5 ± 0.2 (7.9–9.0) μm in width. Two polar capsules occupying approximately half of the myxospore length were unequal in size. The larger polar capsule containing 6 to 7 filament coils measured 5.2 ± 0.3 (4.5–5.8) μm in length and 3.6 ± 0.2 (3.2–3.9) μm in width, while the smaller capsule with 4 to 5 filament coils measured 3.9 ± 0.3 (3.0–4.4) μm in length and 2.5 ± 0.3 (2.1–3.6) μm in width. The comparison of molecular characteristics demonstrated similarities and genetic distances of 18S rDNA sequences of 95.19% - 98.20% and 1.82% - 5.46%, respectively, between M. pseudonobilis n. sp. and its morphologically similar species, and secondary structures were also distinctly different. Moreover, phylogenetic analysis showed that M. pseudonobilis n. sp. was clustered with other myxobolids possessing spores with a blunt anterior end and branched independently. In addition, the morphology of myxosporeans as an important indicator was discussed.     

Molecular and Morphometric Characteristics of Ceratomyxa hamour n. sp. (Myxosporea: Bivalvulida) Infecting the Gallbladder of the Orange‐spotted Grouper Epinephelus coioides from the Arabian Gulf,Saudi Arabia

Ceratomyxa hamour n. sp. was found to infect the gallbladder of the orange‐spotted grouper, Epinephelus coioides located off the Saudi Arabian coast of the Arabian Gulf. The infection was reported as a free‐floating spore in the bile, and pseudoplasmodia were not observed. Mature spores were crescent‐shaped and measured on average 7 μm in length and 16 μm in thickness. The polar capsule, meanwhile, had length to width measurements of 4 μm and 3 μm on average. A periodical survey was conducted throughout a sampling period between December 2012 and December 2013, with the results showing that the parasite was present throughout the year with a mean prevalence of 32.6%. The objective of this study was to characterize this new species based on its morphological and molecular differences from previously described species. Molecular analysis based on the partial sequence of the SSU rDNA gene, showed the highest similarity (97.8%) to Ceratomyxa buri, reported in the cultured yellow tail Seriola quinqueradiata in Japan. Indeed, C. buri and the new species described here formed an individual cluster with a high degree of bootstrap support. This is the first reported species of genus Ceratomyxa from the Arabian Gulf fishes off Saudi Arabia.