Mass mortality event of round sardinella Sardinella aurita Valenciennes associated with Glugea Thélohan, 1891 microsporidian infection off the southern Italian coast.

Intracellular parasites of the genus Glugea Thélohan, 1891 (Microsporidia) comprise about 34 putative species capable of causing high morbidity and mortality in freshwater and marine teleost fishes. In this study, we report on the first mass mortality event associated with Glugea sp. infecting free-ranging round sardinella Sardinella aurita in the southern Tyrrhenian Sea (Italy). Here, we describe the ultrastructure of mature spores of this microsporidian and characterize it molecularly, as well as report its phylogenetic position. Most of the affected fish showed an irregular swelling of its abdomen. At necropsy, a variable number of xenomas, spherical to ellipsoidal in shape, were found in the peritoneal cavity strongly attached to the viscera of all fish. Histological analysis revealed varying severity of chronic inflammation along with occasional necrosis in visceral organs associated with multiple xenoma proliferation. These pathological findings were considered the main cause of this mass mortality event. Morphologically, the present material was closely related to G. sardinellesis and G. thunni. The phylogenetically closest taxa to the newly SSU rDNA sequence were G. thunni and an erroneusly identified  G. plecoglossi, which were very closely related to each other, also suggesting that all these sequences might belong to the same species.

Phylogenetic analysis of Ellipsomyxa species (Myxosporea) and description of Ellipsomyxa gordeyi n. sp. from the gall bladder of mullets (Mugiliformes: Mugilidae) in Nha Trang Bay of the East Sea, Vietnam.

The coastal waters of Vietnam are home to a wide diversity of fishes, but the parasite diversity of these potential hosts is much less well characterized. To begin addressing this knowledge gap, we carried out surveys of myxozoan parasites in fishes collected from Nha Trang Bay in Vietnam's East Sea in 2018-2019. Mugilid fishes were collected in March-April 2018, January-February 2019, and November-December 2019, and examined for myxozoans. Myxospores consistent with those of the genus Ellipsomyxa were found in the gall bladder of four mullet species, and we thoroughly characterized those from Planiliza melinoptera. Myxospores were elliptoid and devoid of striation, with a distinct sinuous suture line. Polar capsules were pyriform and oriented toward the poles of the spore. Morphological features were compared to nominal species and this species from Vietnam was distinct. Phylogenetic analysis based on partial small subunit rDNA sequence revealed that broadly, Ellipsomyxa species split into three phylogenetic lineages, and although in some branches there are groupings by host family, habitat or locality, there are no clear phylogenetic patterns. The new species we encountered in P. melinoptera had a close sister relationship with Ellipsomyxa adlardi, with both species part of a larger subclade within the Ellipsomyxa lineage. Despite this phylogenetic similarity, these species were morphologically distinct, and partial large subunit DNA sequences were only 93% similar to each other. A combination of the morphological characteristics and molecular data suggest that this is an undescribed species and we propose the name Ellipsomyxa gordeyi n. sp.

Morphology, morphogenesis and molecular phylogeny of a new soil ciliate, Lamtostyla paravitiphila nov. spec. (Ciliophora, Hypotrichia).

The morphology and morphogenesis of Lamtostyla paravitiphila nov. spec., a novel soil hypotrichous ciliate collected from eastern China, were investigated based on live observations and protargol-stained specimens. The new species is morphologically characterized as follows: seven to twelve macronuclear nodules, cortical granules absent, 19-26 adoral membranelles, three or four frontoventral cirri, the amphisiellid median cirral row extends to about mid-body and composed of 12-18 cirri, two or three transverse cirri, 27-39 left and 30-41 right marginal cirri, three almost bipolar dorsal kineties. Morphogenetically, it is characterized by the initial formation of six frontal-ventral-transverse cirral anlagen as primary primordia. Notably, the amphisiellid median cirral row and the posterior frontoventral cirrus (or cirri) contribute to the development of the frontal-ventral-transverse cirral anlagen, while the buccal cirrus may not participate in this process. Phylogenetic analyses based on small subunit ribosomal DNA sequence data indicate that the Lamtostyla species with available molecular data do not form a monophyletic group.

Extensive intragenomic variations of the 18S rDNA V4 region in the toxigenic diatom species Pseudo-nitzschia multistriata revealed through high-throughput sequencing.

Metabarcoding analysis is an effective technique for monitoring the domoic acid-producing Pseudo-nitzschia species in marine environments, uncovering high-levels of molecular diversity. However, such efforts may result in the overinterpretation of Pseudo-nitzschia species diversity, as molecular diversity not only encompasses interspecies and intraspecies diversities but also exhibits extensive intragenomic variations (IGVs). In this study, we analyzed the V4 region of the 18S rDNA of 30 strains of Pseudo-nitzschia multistriata collected from the coasts of China. The results showed that each P. multistriata strain harbored about a hundred of unique 18S rDNA V4 sequence varieties, of which each represented by a unique amplicon sequence variant (ASV). This study demonstrated the extensive degree of IGVs in P. multistriata strains, suggesting that IGVs may also present in other Pseudo-nitzschia species and other phytoplankton species. Understanding the scope and levels of IGVs is crucial for accurately interpreting the results of metabarcoding analysis.

Identification of new amoebae strains in rainbow trout (Oncorhynchus mykiss, Walbaum) farms affected by nodular gill disease (NGD) in Northeastern Italy.

Nodular gill disease (NGD) is an emerging condition associated with amoeba trophozoites in freshwater salmonid farms. However, unambiguous identification of the pathogens still must be achieved. This study aimed to identify the amoeba species involved in periodic NGD outbreaks in two rainbow trout (Oncorhynchus mykiss) farms in Northeastern Italy. During four episodes (February-April 2023), 88 fish were euthanized, and their gills were evaluated by macroscopic, microscopic and histopathological examination. The macroscopic and microscopic severity of the lesions and the degree of amoebae infestation were scored and statistically evaluated. One gill arch from each animal was put on non-nutrient agar (NNA) Petri dishes for amoeba isolation, cultivation and subsequent identification with SSU rDNA sequencing. Histopathology confirmed moderate to severe lesions consistent with NGD and mild to moderate amoeba infestation. The presence of amoebae was significantly correlated with lesion severity. Light microscopy of cultured amoebae strains and SSU rDNA analysis revealed the presence of a previously characterized amoeba Naegleria sp. strain GERK and several new strains: two strains from Hartmannelidae, three vannelid amoebae from the genus Ripella and cercozoan amoeba Rosculus. Despite the uncertainty in NGD etiopathogenesis and amoebae pathogenic role, identifying known and new amoebae leans towards a possible multi-aetiological origin.

Didymium arenosum, a myxomycete new to science from the confluence of deserts in northwestern China.

A new myxomycete species, Didymium arenosum, was described based on morphological evidence and phylogenetic analyses. The species was discovered in the arid region at the confluence of the Badain Jaran desert and Tengger desert on the leaves of Betula platyphylla and was cultivated in a moist chamber culture. Morphologically, the species is distinguished by the greenish-yellow calcium carbonate crystals on the surface and the spores covered with small warts, some of which are connected into a short line. A phylogenetic analysis of D. arenosum strongly supports its classification as a separate clade. The spore to spore agar culture of D. arenosum requires 23 days, and this study provides a detailed description of its life cycle.

Description of Holostichides (Extraholostichides) eastensis tianjinensis subgen. nov. subspec. nov. (Ciliophora, Hypotricha) from northern China.

The morphology and morphogenesis of a new urostylid, Holostichides (Extraholostichides) eastensis tianjinensis subgen. nov. subspec. nov. were analyzed. The new subspecies differs from the nominotypical subspecies H. (Extraholostichides) eastensis eastensis Wang et al., 2022 by the relatively long frontoterminal row (about 60% vs. 30% of body length), colorless cortical granules (vs. dark brown), two (vs. one) parabuccal cirri, and usually an extra cirrus behind the first midventral pair (vs. lacking). Based on the difference in the frontal ciliature, we split Holostichides into two subgenera: H. (Extraholostichides) subgen. nov. (type species Holostichides eastensis Wang et al., 2022; with a short cirral row behind the middle frontal cirrus) and H. (Holostichides) Foissner, 1987 (type species Holostichides chardezi Foissner, 1987; lacking this short row). The main morphogenetic characters of the new subspecies are very similar to those of H. (Extraholostichides) eastensis eastensis except for some minor differences. Phylogenetic analyses based on SSU rDNA sequences indicate that H. (Extraholostichides) subgen. nov. is monophyletic and nested within the monophyletic genus Holostichides, which is sister to Eschaneustyla lugeri.

Eimerian and capillariid infection in farmed ring-necked pheasants (Phasianus colchicus karpowi) in Ehime, Japan, with special reference to their phylogenetic relationships with congeners.

We performed a parasitological examination of the gastrointestinal tract of farmed ring-necked pheasants (Phasianus colchicus karpowi) on two farms in Ehime, Japan. Fecal examination through flotation and sedimentation methods (43, 103, and 50 samples in three consecutive years from 2020, respectively) detected coccidian oocysts (5-58%), or capillarid (40-56%) and heterakid eggs (45-72%). Following artificial sporology, most sporulated coccidian oocysts were ellipsoidal without micropyle nor residuum, but with 1-3 polar refractile granules, morphologically reminiscent of Eimeria phasiani (Apicomplexa: Eucoccidiorida: Eimeriidae). Intensive sequencing of mitochondrial cytochrome c oxidase subunit I gene (cox-1) using pan-eimerian primers and multiple oocyst samples from different pheasants indicated a single species. We characterized, for the first time, the cox-1 sequence of E. phasiani, known to be prevalent in wild and captive ring-necked pheasants worldwide. Worm recovery under a dissection microscope revealed two capillariid and one heterakid nematode species: Eucoleus perforans (Nematoda: Trichocephalida: Capillariidae) in the esophageal epithelium (prevalence, 8-73%), Capillaria phasianina (Capillariidae) in the cecal mucosa (10-87%), and Heterakis gallinarum (Nematoda: Ascaridida: Heterakidae) in the cecal lumen (69-88%). The small subunit ribosomal RNA gene (SSU rDNA) of E. perforans was perfectly identical to that in a previous isolate from farmed Japanese green pheasants (Phasianus colchicus versicolor) at a distant locality in Japan. The SSU rDNA of C. phasianina was characterized, for the first time, demonstrating a sister relationship with Capillaria anatis, parasites found in the ceca of domestic ducks, geese, and various wild anatid birds.

Morphology and phylogeny of four trachelocercid ciliates (Ciliophora, Karyorelictea, Trachelocercidae) from North China Sea, with description of a new species.

Trachelocercids are common ciliates in marine sandy intertidal zones, however, only few species have been described using modern taxonomic techniques, with several earlier descriptions still lacking primary data, such as a detailed description of the oral ciliature. For this reason, systematics of the family Trachelocercidae Kent, 1881 resulted in paraphyletic genera and needs a critical revision. As an attempt to fill the gap of knowledge for this group, this study presents one new species description, Tracheloraphis apodiscolor n. sp., along with redescriptions of three lesser-known trachelocercid species, Trachelocerca bodiani (Dragesco, 1963) Dragesco, 2002, Trachelocerca ditis (Wright, 1982) Foissner & Dragesco, 1996 and Prototrachelocerca fasciolata (Sauerbrey, 1928) Foissner, 1996, collected from coastal marine habitats at Qingdao (China), using live and protargol-stained specimens. Tracheloraphis apodiscolor n. sp. can be distinguished from its closest related congener, T. discolor, by a shorter body length and fewer somatic kineties. Molecular data of T. apodiscolor n. sp. and T. bodiani were provided for the first time. Additionally, based on the Qingdao populations, we provide improved diagnoses for T. ditis and P. fasciolata. Phylogenetic analyses were performed and discussed, as there is strong support for paraphyly of the genera Tracheloraphis and Trachelocerca. In general, more integrative studies based on taxonomy, ultrastructure as well as molecular data are needed to properly shed light on the systematics of trachelocercids.

Oogamochlamys kurilensis sp. nov. (Chlorophyta, Volvocales) from the Soils of Iturup Island (Sakhalin Region, Russia).

A strain of oogamous biflagellate green alga was isolated during a study on soil algal diversity in the Russian Far East (Sakhalin Region, Iturup Island) and examined using an integrative approach. Phylogenetic analyses, based on the SSU rDNA gene, resolved the new strain as a part of the RL clade (sensu Watanabe and Nakada) within Oogamochlamydinia (Volvocales, Chlorophyceae). The strain was similar to members of the genus Oogamochlamys (parietal and massive cup-shaped chloroplasts; two apical contractile vacuoles), but was, however, distinguished from them based on the size and shape of the mature vegetative cells, the flagellar length, the presence of only one pyrenoid in both the mature vegetative cells and the zoospores, the anterior nucleus position, and the spermatozoids' shape. Although a concept of the genus Oogamochlamys has been compromised in recent phylogenetic analysis based on the SSU rDNA sequence data and its likely affinity to anisogamous Chlamydomonas allensworthii, we described the strain from Iturup Island as Oogamochlamys kurilensis sp. nov.

Myxobolus xiushanensis n. sp. (Myxozoa: Myxobolidae) infecting the gill arches of Yellowhead Catfish Tachysurus fulvidraco from China.

OBJECTIVE: Myxosporidiosis of bagrid fishes has been a focus of aquaculture research in recent years. The purpose of this study is to characterize a novel myxobolid, named Myxobolus xiushanensis n. sp., infecting Yellowhead Catfish Tachysurus fulvidraco in China. METHODS: We used molecular biology, morphology, phylogeny, and histopathology in the present study. RESULT: Mature myxospores were circular to ellipsoidal in valve view, measuring 12.2 ± 0.4 µm (mean ± SD; range = 11.2-13.2 µm) in length and 10.6 ± 0.4 µm (9.5-11.1 µm) in width. Two oval polar capsules were equal in width (3.4 ± 0.2 µm; 3.0-3.8 µm) but slightly unequal in length: 5.6 ± 0.3 µm (5.3-6.1 µm) and 4.7 ± 0.2 µm (4.4-5.5 µm). The polar capsule was packed with five to seven spirals of polar tubules. Histopathological investigation demonstrated that the plasmodium under the cuticular layer of the gill arch only induced a local inflammatory response and did not cause serious damage to the gill arch's internal structure. The two small subunit (SSU) ribosomal DNA sequences of M. xiushanensis n. sp. showed 100% similarity and uniqueness, and the highest similarity with other myxosporean sequences in GenBank was 90.27% (query coverage = 94%). The secondary structures of the SSU ribosomal RNA revealed that the present species was distinctly different from related species in regions V4 and V7. Phylogenetic analysis showed that M. xiushanensis n. sp. clustered independently within a branch. CONCLUSION: These results enrich our understanding of the biodiversity of myxobolids infecting bagrid fishes and provide fundamental data for the diagnosis of myxosporidiosis.

Morphological, histopathological, ultrastructural and phylogenetic analysis of Henneguya archosargus n. sp. (Cnidaria, Myxosporea) infecting the sparid fish Archosargus probatocephalus in Brazilian waters.

The introduction of new fish species to the aquaculture industry is essential to halt the progressive decline of natural fish stocks. The sheepshead Archosargus probatocephalus is a commercially valuable sparid fish with potential for breeding in captivity, but with limited information regarding parasitic infections that could pose a significant threat for its sustainable production. Thus, the present study aimed to study the myxozoan diversity infecting A. probatocephalus. A novel Henneguya sp. was detected forming plasmodia in the gill lamellae of specimens inhabiting the Brazilian coast, and is characterized based on morphological, histopathological, ultrastructural, molecular, and phylogenetic data. Myxospore total length was 21.3 ± 0.8 µm, with myxospore body 10.0 ± 0.5 µm long, 6.2 ± 0.3 µm wide, and 4.8 ± 0.5 µm thick. Caudal appendages were 10.3 ± 0.5 µm long and did not present any type of coating. Two pyriform polar capsules, 3.4 ± 0.3 µm long and 1.5 ± 0.2 µm wide, each containing an isofilar polar tubule with 4-5 coils. Histopathological analyses showed large intralamellar polysporic plasmodia associated with vascular congestion of the gill filament and gill lamellae, as well as epithelial hyperplasia causing partial or total fusion of gill lamellae. Maximum likelihood and Baysesian inference SSU rDNA-based phylogenetic analyses showed the novel sequence grouped within the marine clade of Henneguya spp. that mostly parasitize fishes belonging to Eupercaria incertae sedis.

Impact of mycoheterotrophy on the growth of Gentiana zollingeri (Gentianaceae), as suggested by size variation, morphology, and 13C abundance of flowering shoots.

Gentiana zollingeri is an annual photosynthetic plant that employs a mycoheterotrophic growth strategy during its underground seedling stage (initial mycoheterotrophy). Notably, the morphological characteristics of its flowering shoots, such as shoot size, leaf size, and leaf color, are highly variable, and it was hypothesized that these variations may be linked to nutritional mode. The morphological characteristics of G. zollingeri individuals were thus investigated alongside environmental factors, 13C abundance, and diversity of colonizing arbuscular mycorrhizal (AM) fungi. The majority of G. zollingeri flowering individuals were found to exhibit a high affinity for the specific AM fungi that exclusively colonize roots of the mycoheterotrophic seedlings, while other phylogenetically diverse AM fungi could also be detected. The leaves to shoot dry weight ratio (leaf ratio) was negatively correlated with the canopy openness in the habitat, suggesting that leaf development is impeded in sunny conditions. Furthermore, the shoot weight of G. zollingeri was positively correlated with leaf 13C abundance. Given that 13C enrichment can provide indirect evidence of mycoheterotrophy in AM plants, the results suggest that the utilization of carbon obtained through mycoheterotrophy, at least during the underground seedling stage, is crucial for G. zollingeri.

Morphological, histological and phylogenetic identification of three species of Myxobolus (Myxosporea: Myxobolidae) infecting different carp lineages in China.

The global cultivation of common carp Cyprinus carpio is developed primarily for either food or recreational purposes and myxosporean infections causing significant economic losses are regularly troublesome for carp farmers. However, most myxosporean species are poorly characterized, making it difficult to correctly elaborate on their parasitism mode and determine pathogenicity. Here, based on an integrative approach, we supplemented fundamental information on three Myxobolus species infecting different carp lineages in China. Myxobolus elliptoides Wu et Chen, 1987; Nine new species of Myxosporida from freshwater fish of Wuhu lake, Hubei, China. Acta Hydrobiologica Sinica, 11, 161 formed yellowish pseudocysts in the anal fin of common carp and were observed with ellipsoidal myxospores and two polar capsules of distinct dimensions. The dermal tissue within the fin ray was regarded as the type site for growing plasmodia of M. elliptoides. Myxobolus basilamellaris Lom et Molnar, 1983; Myxobolus basilamellaris sp. n. (myxozoa, Myxosporea), a parasite of the gills of common carp (Cyprinus carpio L.). Folia Parasitologica, 30, 1 aggregated ellipsoidal myxospores at the base of the gill filaments of koi carp juvenile, causing significant tissue damage. Myxobolus artus Achmerov, 1960, enwrapped in diffuse pseudocysts, was observed throughout the trunk muscle of mirror carp. Its oblate myxospores were asymmetrical and contained two unequal-sized polar capsules. According to the localization of large plasmodia, inter- and intramuscular preferences were displayed by M. artus. For precise species identification, we provided the SSU rDNA sequences for each species of Myxobolus. Among them, M. elliptoides was molecularly characterized for the first time, showing the highest 94.21% identity to Thelohanellus sinensis (KY469292). Phylogenetically, the affinity of both M. artus and M. basilamellaris to their conspecific species derived from different carp lineages was highly supported. Moreover, the intermixed cluster of Myxobolus species, including M. elliptoides, with those of Thelohanellus species provided evidence for querying the monophyletic evolution history of these taxa. This work updates the appreciation of the concerned species and enhances our understanding of the parasite fauna of common carp.

Molecular confirmation of pearl formation in arctic mussels (Mytilus edulis) caused by Gymnophallus bursicola (Odhner 1900) metacercariae.

In recent field studies, suspected gymnophallid metacercariae were histologically located in the mantle of mussels from the Norwegian Sea. Mussels from the sites in which that infection was detected also presented abnormally high pearl numbers. It has been previously described that gymnophallid metacercariae could cause pearl formation processes in mussels, as a host reaction to encapsulate these metacercariae. Given the pathological host reaction these parasites elicit, a study was performed to identify gymnophallid metacercariae found in mussels collected from Tromsø at morphological and molecular level and to assess, by the use of molecular tools, the relationship between the parasite and the biological material inside the pearls. As a result, Gymnophallus bursicola metacercariae infecting Norwegian Mytilus edulis were identified according to morphological characters, along with the first 18S rDNA and COI sequences for this trematode species. In addition, parasite DNA from the core of the pearls was extracted and amplified for the first time, confirming the parasitological origin of these pearls. This procedure could allow identifying different parasitic organisms responsible for the generation of pearls in bivalves.

Novel contributions to the molecular and morphological diversity of freshwater monothalamid foraminifera: Description of six new species.

Non-marine monothalamous foraminifera are common in freshwater and soil habitats. They comprise a poorly-known group lacking sufficient information about diversity, morphology, reproduction, distribution and ecology. Based on an integrative morphological and molecular approach we describe a new family, a new genus and six new species of freshwater monothalamids from different localities in the Netherlands and France. We establish Astroperula as a new genus of organic walled freshwater foraminifera that contains two species, Astroperula dumacki and Astroperula parvipila. Furthermore, two new agglutinated freshwater monothalamids are described and illustrated, Limnogromia leanneae and Lacogromia pawlowskii, one new organic walled, Velamentofex dujardini, and a new naked monothalamid, Haplomyxa retiforma. Additional information is provided about a special form of cell division in Claparedellus lachmannii and L. leanneae, and feeding behavior in cultures of V. dujardini. Morphological observations are added for an unidentified Limnogromia sampled from the Netherlands and two types of Lacogromia sampled from an alpine region in the French Pyrenees and a karst sinkhole in Bosnia and Herzegovina. The present study provides additional insight into the ecology, diversity and occurrence of freshwater monothalamids and emphasizes the fact that a combination of morphological and molecular methods is necessary to clearly distinguish species in this group.

Histopathological evaluation of the infection elicited by three species of Myxobolus (Cnidaria: Myxosporea), with identification of Myxobolusxiaoganensis n. sp. isolated from the silver carp Hypophthalmichthys molitrix.

Several parasites infecting the Asian carp species have been broadly spread along with the global fish trade. However, the diversity of specific parasite groups and their pattern of parasitism remain insufficiently elucidated even in their native regions. Here, we conducted a holistic identification and histological analysis of three Myxobolus species. The oblate myxospores of the first isolates were found infecting the spleen of silver carp Hypophthalmichthys molitrix, measuring 6.4 ± 0.4 (5.4-7.1) µm in length, 8.2 ± 0.4 (7.5-9.0) in width, and 5.9 ± 0.3 (5.2-6.2) in thickness. They were morphologically distinct from other congeners and regarded as a novel species, Myxobolus xiaoganensis n. sp. For the second isolates, we associated the formation of round plasmodia on the gill raker of silver carp with Myxobolus allotypica Chen, 1998. The third isolates, encapsulated in the intestinal serosa membrane of the grass carp Ctenopharyngodon idella, was proved to be conspecific to Myxobolus huasaensis Chen, 1998. While M. xiaoganensis n. sp. and M. huasaensis exhibited distinct origins, with genetic differences exceeding 4% from other congeners, M. allotypica displayed complete genetic congruence with an item available in Genbank. Histologically, myxospores of M. xiaoganensis n. sp. were scattered in the spleen, and the branchial and intestinal infections of M. allotypica and M. huasaensis were determined, respectively. Phylogenetic analysis demonstrated a non-monophyletic origin of both the Thelohanellus and Myxobolus genera, with a remarkable association of host affinity with myxosporean clustering.

A new freshwater Ceratomyxa species (Myxozoa: Ceratomyxidae) parasitizing a sciaenid fish from the Amazon Basin, Brazil.

Myxozoans of Ceratomyxidae Doflein, 1899 are common coelozoic parasites of marine life, and are also found less frequently in freshwater fish. The present study describes Ceratomyxa ranunculiformis n. sp. as a new freshwater myxosporean species infecting the gall bladder of the Amazonian sciaenid Plagioscion squamosissimus. The new Ceratomyxa was described based on its host, myxospore morphology, ribosomal rDNA gene sequencing, parasite distribution, and phylogenetic analysis. Immature and mature plasmodia were tadpole-shaped or pyriform, and exhibited slow undulatory motility. The myxospores were elongated and crescent-shaped in the frontal view, with a sutural line between two valves, which had rounded ends. The measurements of the formalin-fixed myxospores were: average length 4.9 (4.0-6.6) µm, average thickness 37.6 (32.4-43.9) µm, average posterior angle 165° (154°-173°). Two ovoid polar capsules of equal size, average length 2.0 (1.4-3.0) µm and average width 1.9 (1.4-2.4) µm, were located adjacent to the suture and contained polar filaments with 2-3 coils. The integrated comparative analysis of the morphological characteristics and molecular analyses of the ribosomal rDNA genes supported the identification of a new species of coelozoic Ceratomyxa. Maximum likelihood analyses showed the new species clustering within a well-supported clade, together with all the other Amazonian freshwater ceratomyxids.

The description of Myxobolus meijiangensis n. sp. (Myxozoa: Myxobolidae) and its pathogenicity to the gills of goldfish.

Myxobolus Bütschli, 1882 is the most speciose myxozoan genus, although some species have only been described according to the morphological characteristics of spores. In the present study, a new Myxobolus species infecting the gill lamellae of goldfish from Chongqing, China, was described using a comprehensive analysis of morphological, molecular, and histological data. Mature spores were flat-pear in valvular view with tapering anterior and rounded posterior ends, measuring 11.0 ± 0.4 (10.4-11.6) µm in length and 10.3 ± 0.3 (9.6-11.0) µm in width. Two equal-sized elongate pyriform polar capsules were 5.6 ± 0.6 (4.5-6.4) µm long and 3.5 ± 0.5 (2.4-4.1) µm wide. Polar tubules were coiled with 8 or 9 turns. The small-subunit ribosomal DNA gene sequence length of the present species was 1951 nt, and the highest similarity was 97.99% with M. pyramidis. Comparative analysis of the morphological and molecular data revealed that the present species was distinct from other known myxosporeans. Plasmodia were located at the interlamellar troughs nearing the top of the primary gills. Infection by the present species destroyed the original structure of gill lamellae and caused an inflammatory response, eventually leading to fish dyspnea. The morphological, molecular, and pathological data from the present study can be used for aquaculture since they provide guidance for easy detection and future control of this myxosporidiosis.

New evidence of consistency between phylogeny and morphology for two taxa in ciliated protists, the subclasses Oligotrichia and Choreotrichia (Protista, Ciliophora).

Marine planktonic ciliates are largely oligotrichs and choreotrichs, which are two subclasses of the class Spirotrichea. The current phylogenetic assignments of oligotrichs and choreotrichs are inconsistent with previous results based on morphological features, probably hindered by the limited information from a single gene locus. Here we provide 53 new sequences from small subunit ribosomal RNA (SSU rDNA), ITS1-5.8S rDNA-ITS2, and large subunit ribosomal RNA (LSU rDNA) gene loci in 25 oligotrich and choreotrich species. We also predict RNA secondary structures for the ITS2 regions in 55 species, 48 species of which are reported for the first time. Based on these novel data, we make a more comprehensive phylogenetic reconstruction, revealing consistency between morphological taxonomy and an updated phylogenetic system for oligotrichs and choreotrichs. With the addition of data from ciliature patterns and genes, the phylogenetic analysis of the subclass Oligotrichia suggests three evolutionary trajectories, among which: 1) Novistrombidium asserts an ancestral ciliary pattern in Oligotrichia; 2) the subgenera division of Novistrombidium and Parallelostrombidium are fully supported; 3) the three families (Tontoniidae, Pelagostrombidiidae and Cyrtostrombidiidae) all evolved from the most diverse family Strombidiidae, which explains why strombidiids consistently form polyphyletic clades. In the subclass Choreotrichia, Strombidinopsis likely possesses an ancestral position to other choreotrichs, and both phylogenetic analysis and RNA secondary structure prediction support the hypothesis that tintinnids may have evolved from Strombidinopsis. The results presented here offer an updated hypothesis for the evolutionary history of oligotrichs and choreotrichs based on new evidence obtained by expanding sampling of molecular information across multiple gene loci.