Integration of transcriptomic and metabolomic profiling of encystation in Cryptocaryon irritans regulated by rapamycin.

Encystation in Cryptocaryon irritans is a fundamental process for environmental resistance and development. Autophagy participates in the encystation of ciliates, and rapamycin can induce autophagy in the cells. A set of genes and metabolites related to autophagy and encystation are highly elaborative. The existence of these genes and metabolites and their role are well characterized. However, little is known about their role in protozoans such as ciliates. The newly produced C. irritans protomonts were exposed to an optimal concentration of rapamycin (1400 nM), and the survival, encystation, microstructure/ultrastructure, transcriptomic and metabolomic profile in treated and control protomonts were investigated. The results showed that exposure of protomonts to rapamycin at 4 h significantly lowered the survival and encystation rates to 91.62 % and 98.44 % compared to the control group (100 %, p ≤ 0.05). Morphological alterations observed in light microscopy and transmission electron microscopy (TEM) demonstrated that the drug significantly changed cell symmetry by causing the formation of various autophagic vacuoles/vesicles. The transcriptome sequencing of rapamycin-treated protomont revealed that 2249 (1837 up-regulated and 977 down-regulated) differentially expressed genes (DEGs) were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 226 DEGs were successfully annotated in 21 pathways (p˂0.05), including most enriched pathways apoptosis and phagosome with 25 and 24 DEGs, respectively. Most unigenes were assigned to autophagy-related pathways; 24 DEGs were classified into phagosomes, and 15 DEGs were assigned to lysosome pathways. Cytoskeleton and cell progression-associated genes were down-regulated. Besides, cell death-inducing proteins were up-regulated. The metabolomic analysis revealed exposure to rapamycin treatment enhanced protomont metabolites, including L-Cysteine, which is related to autophagy. Rapamycin had influenced the gene and metabolites of protomont; activating autophagy with inhibition of mechanistic target of rapamycin, (mTOR). The process negatively influences protomont morphology, encystation, and survival. Further autophagy-related gene silencing can be investigated via genome sequencing of C. irritans to study encystation.

A light and electron microscopical study on the resting cyst of the tintinnid Schmidingerella (Alveolata, Ciliophora) including a phylogeny-aware comparison.

Resting cysts protect ciliates against adverse environmental conditions. The morphology and ultrastructure of resting cysts has been described in very few Oligotrichea, a group of mainly marine planktonic ciliates. The present study provides the first ultrastructural data for loricate choreotrichids, applying light and electron microscopy on the cysts of the tintinnid Schmidingerella meunieri (Kofoid and Campbell, 1929) Agatha and Strüder-Kypke, 2012. The morphology of live cysts and the wall ultrastructure of cryofixed cysts were morphometrically analysed. The resting cyst is roughly flask-shaped, broadening to a slightly concave, laterally protruding anterior plate. An emergence pore closed by a skull cap-shaped papula is directed to the bottom of the lorica on the opposite side of the cyst. The cyst wall consists of an ectocyst, mesocyst, and endocyst differing in thickness, structure, and nitrogen concentration as revealed by conventional transmission electron microscopy, electron energy loss spectroscopy, and electron spectroscopic imaging. The cysts of S. meunieri belong to the kinetosome-resorbing type, which also occurs in the majority of hypotrich ciliates. Two main features (flask-shape and presence of an emergence pore) are shared with the closely related aloricate choreotrichids and oligotrichids, distinguishing the Oligotrichea from the hypotrich and the more distantly related euplotid ciliates.

A detailed description of a Brazilian Holophrya teres (Ehrenberg, 1834) and nomenclatural revision of the genus Holophrya (Ciliophora, Prostomatida).

I studied a Brazilian population of Holophrya teres (Ehrenberg, 1834) Foissner, Berger and Kohmann, 1994, using live observation, morphometry, silver impregnation, and scanning electron microscopy. This showed a fair similarity with European populations, especially in having a large (about 13 × 5 µm in vivo) micronucleus pyriform in broad-side view and cuneate in narrow-side view. Several new structures were discovered, viz., an internal oral basket, teeth on anterior end of the oral basket rods, and a buccal seal closing the oral basket when not feeding. Based on this knowledge, I provide an improved diagnosis for H. teres, which can be used as template in further species descriptions. Depending on brosse implantation in the somatic ciliature, the genus was split in Holophrya, Hillerophrya nov. gen., Vdacnyophrya nov. gen., and Bardeleophrya nov. gen. Twenty-one Prorodon species were combined with the holophryid genera, using brosse and thick oral basket rods as main markers. This revealed two new species, viz., Holophrya longiarmata nov. spec. and H. agamalievi nov. spec.

Trichodinids (Ciliophora: Trichodinidae) on Rocky-tidal Fishes from the Baja California Peninsula, Mexico.

Information regarding trichodinid ectoparasites on marine fishes of North America is relatively scarce. In this study, 5 ciliate species from the family Trichodinidae were found associated with 8 fish hosts from the rocky intertidal zone of the western coast of the Baja California Peninsula (BCP), Mexico. All of the host-parasite relationships recorded here are new. Furthermore, 3 of the trichodinid species found are recorded for the first time for Mexico. Trichodinids taxa do not show a noticeable distributional gradient along the BCP, which suggests a wide-continuous distribution of the species throughout the study area.

New contributions to two ciliate genera (Ciliophora, Heterotrichea) based on morphological and molecular analyses, with description of a new Gruberia species.

BACKGROUND: Heterotrichous ciliates are common members of microeukaryote communities which play important roles in both the transfer of material and the flow of energy in aquatic food webs. This group has been known for over two centuries due to their large body size and cosmopolitan distribution. Nevertheless, species identification and phylogenetic relationships of heterotrichs remain challenging due to the lack of accurate morphological information and insufficient molecular data. RESULTS: The morphology and phylogeny of two heterotrichous ciliates, namely Gruberia foissneri spec. nov. and Linostomella vorticella (Ehrenberg, 1833) Aescht in Foissner et al., 1999, were studied using rigorous methods (living morphology, stained preparations, and small subunit rDNA sequence data). Gruberia foissneri spec. nov. is morphologically very similar to G. uninucleata Kahl, 1932, however, it can be distinguished from the latter by having more ciliary rows (about 32 vs. about 20) and macronuclear shape (sausage-shaped vs. ellipsoid). Based on a combination of previous and present studies, an improved diagnosis of L. vorticella is supplied and several taxonomic anomalies are clarified. In addition, phylogenetic analyses based on SSU rDNA sequence data support the generic assignment of these two species. CONCLUSIONS: Modern ciliate taxonomy should be performed by means of detailed living observation, stained preparations and molecular information. For those species that have been reported in previous studies, it is necessary to provide as much useful information as possible using state-of-the-art methods in order to resolve taxonomic anomalies.

Ultrastructural Studies on a Model Tintinnid - Schmidingerella meunieri (Kofoid & Campbell, 1929) Agatha & Strüder-Kypke, 2012 (Ciliophora). II. The Oral Apparatus.

The ultrastructure of the oral apparatus is supposed to be significant for elucidating more recent common ancestry and might thus provide support for particular groupings of oligotrichean ciliates. The transmission electron microscopical study on mainly cryofixed Schmidingerella meunieri specimens provides the first detailed data for tintinnids and Oligotrichea in general. Ten new characters are included into the cladistic analysis. These features together with the very limited body of literature suggest that substantial changes in the oral ultrastructure correlate only with the formation of a circular adoral zone in choreotrichids. Despite homoplasious morphological and ontogenetic adaptations to the planktonic lifestyle in halteriid hypotrichs and oligotrichids, their oral apparatuses generally retain the plesiomorphic ultrastructure of the Perilemmaphora. The highly complex ultrastructure of the adoral zone is thus able to accomplish an extension in the zone's functionality without obvious changes; only the position of the adoral zone at the apical cell portion together with a globular to obconical cell shape are apparently crucial. Merely, minute apomorphies characterise the Oligotrichea and tintinnids, respectively. Tintinnids with derived somatic ciliary patterns possess distinct microtubular bundles connecting the oral apparatus with the myoneme in the peduncle.

Observations on the oral organelle, cytopharynx, and subpellicular structure of a Dileptus sp.

We used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to observe the oral organelle, cytopharynx, and subpellicular structure of a Dileptus sp. The main results were as follows: (a) the cytostome was located on the ventral surface of the base of the beak, surrounded by a periportal matrix that integrated 135 microtube bundles. When these microtube bundles contract, radially arranged into a disk, the cytostome was closed. When these microtube bundles were stretch, they fell into the cytostome and opens. The diameter of the cytostome was about 16 µm regardless of its closure or opening, indicating that the contraction or elongation of these microtube bundles did not change the size of the cytostome, which was only related to whether it blocked the cytostome, thus determining the opening and closing of the cytostome. There were many microtube bundles on two sides of the feeding trough, which could widen or narrow the feeding trough and facilitate beak feeding. (b) The cytopharynx was basket-like without a bottom with a diameter of about 6 µm and was woven from two kind fibers about 0.08 and 0.19 µm. (c) There were two types of extrusomes under the pellicle. Using transmission electron microscopy，the Type I extrusomes showed narrow and long egg shape, its cross section was circular which is composed by various electronic density of concentric. Using the scanning electron microscope, they were two slightly thin clavate, the length was about 5 µm, the diameter of the middle section was about 0.75 µm, and the diameter of the two ends was about 0.32 µm, they were distributed abundantly between the microtubule fasciculi which were located on both sides of the gap on the feeding groove. Using transmission electron microscopy, the Type II extrusomes showed egg shape. Using the scanning electron microscopy, they were about 1.6 × 0.8 µm in size, they were distributed abundantly under the body pellicle while rarely the proboscis. In addition, many different of developmental stages two types of extrusomes could be also seen in the cytoplasm. (d) There were very well-developed fibrous systems under the pellicle that were woven from fibers about 0.14 µm in diameter that attached to the pellicle and bound some organelles in the cytoplasm (e.g., mitochondria, extrusomes) and other structures to the cytoplasm and maintained cell morphology. The results of this study not only supplement and enrich the morphological contents of the Dileptus sp., but also provide the basis for the study of the taxonomy of the Dileptus sp. It also provides a new method for researchers to explore the morphology and structure of ciliate cells under the cortex by SEM.

Phylogenetic position of Nyctotherus teleacus isolated from a tortoise (Astrochelys radiata) and its electron microscopic features.

A commensal ciliate was isolated from the stool of a tortoise (Astrochelys radiata). The ciliate was classified as Nyctotherus teleacus, according to its basic morphological features. Electron microscopic observations using cultured N. teleacus (NictoT1 strain) revealed many spherical hydrogenosomes and methanogen-suspected bacteria, together with a characteristic triangular macronucleus containing many spherical chromosomes in the cytoplasm of NictoT1. The results of phylogenetic analysis showed that NictoT1 was included in the cluster of Nyctotheroides spp. (family Nyctotheridae). Nyctotheroides spp. commonly infest amphibians, which are taxonomically closely related to reptiles, including the tortoises evaluated in the present study.

Genomics of New Ciliate Lineages Provides Insight into the Evolution of Obligate Anaerobiosis.

Oxygen plays a crucial role in energetic metabolism of most eukaryotes. Yet adaptations to low-oxygen concentrations leading to anaerobiosis have independently arisen in many eukaryotic lineages, resulting in a broad spectrum of reduced and modified mitochondrion-related organelles (MROs). In this study, we present the discovery of two new class-level lineages of free-living marine anaerobic ciliates, Muranotrichea, cl. nov. and Parablepharismea, cl. nov., that, together with the class Armophorea, form a major clade of obligate anaerobes (APM ciliates) within the Spirotrichea, Armophorea, and Litostomatea (SAL) group. To deepen our understanding of the evolution of anaerobiosis in ciliates, we predicted the mitochondrial metabolism of cultured representatives from all three classes in the APM clade by using transcriptomic and metagenomic data and performed phylogenomic analyses to assess their evolutionary relationships. The predicted mitochondrial metabolism of representatives from the APM ciliates reveals functional adaptations of metabolic pathways that were present in their last common ancestor and likely led to the successful colonization and diversification of the group in various anoxic environments. Furthermore, we discuss the possible relationship of Parablepharismea to the uncultured deep-sea class Cariacotrichea on the basis of single-gene analyses. Like most anaerobic ciliates, all studied species of the APM clade host symbionts, which we propose to be a significant accelerating factor in the transitions to an obligately anaerobic lifestyle. Our results provide an insight into the evolutionary mechanisms of early transitions to anaerobiosis and shed light on fine-scale adaptations in MROs over a relatively short evolutionary time frame.

Documentation of a new hypotrich species in the family Amphisiellidae, Lamtostyla gui n. sp. (Protista, Ciliophora) using a multidisciplinary approach.

An integrated approach considering both morphologic and molecular data is now required to improve biodiversity estimations and provide more robust systematics interpretations in hypotrichs, a highly differentiated group of ciliates. In present study, we document a new hypotrich species, Lamtostyla gui n. sp., collected from Chongming wetland, Shanghai, China, based on investigations using living observation, protargol staining, scanning and transmission electron microscopy, and gene sequencing. The new species is mainly recognized by having a short amphisiellid median cirral row composed of four cirri, three frontoventral cirri, three dorsal kinetids, four to eight macronuclear nodules, and small colorless cortical granules distributed as rosettes around dorsal bristles. Transmission electron microscope observation finds the associated microtubules of cirri and pharyngeal discs of L. gui are distinct from those in other hypotrichs. Morphogenesis of this species indicates that parental adoral membranelles retained intact or partial renewed is a potential feature to separate Lamtostyla granulifera-group and Lamtostyla lamottei-group. Phylogenetic analysis based on small subunit ribosomal RNA (rRNA) gene shows that this molecular marker is not useful to resolve phylogenetic relationships of the genus Lamtostyla, as well as many other hypotrichous taxa. We additionally characterize the internal transcribed spacers (ITS) region and the almost complete large subunit rRNA, which will be essential for future studies aimed at solving phylogenetic problems of Lamtostyla, or even the family Amphisiellidae. As a final remark, the critical screening of GenBank using ITS genes of our organism allows us to recognize a large amount of hypotrichous sequences have been misclassified as fungi. This observation suggests that hypotrichs could be frequently found in fungi-rich environment and overlooked by fungal specialists.

Morphology, Morphogenesis, and Molecular Phylogeny of Neobakuella aenigmatica n. sp. (Ciliophora, Spirotrichea, Bakuellidae).

The morphology and morphogenesis of a new ciliate species, Neobakuella aenigmatica n. sp., which was discovered in an estuary in Korea, were investigated, using live observation, protargol impregnation, and scanning electron microscopy. This new species is characterized by a large (185-300 × 55-105 µm in vivo), elongate-ellipsoidal, flexible but not contractile body. It has ellipsoidal, yellowish cortical granules, 1.3 × 1.0 µm in size. The species has invariably 3 frontal and 2 frontoterminal cirri, about 5-10 buccal and 1-6 parabuccal cirri, 7 midventral rows, and 1 right and 2-4 left marginal rows. The outer left marginal row(s) consists of 1-7 short rows of cirri. The nuclear apparatus comprises 130 macronuclear nodules and 2 spherical micronuclei on average. The dorsal ciliature consists of 3 dorsal kineties. The leftmost left marginal row(s) likely develops from anlagen originating from both the rightmost and leftmost left marginal row(s). The molecular phylogenetic tree based on SSU rDNA suggests the nonmonophyly of the genus Neobakuella.

Thiotrophic bacterial symbiont induces polyphenism in giant ciliate host Zoothamnium niveum.

Evolutionary theory predicts potential shifts between cooperative and uncooperative behaviour under fluctuating environmental conditions. This leads to unstable benefits to the partners and restricts the evolution of dependence. High dependence is usually found in those hosts in which vertically transmitted symbionts provide nutrients reliably. Here we study host dependence in the marine, giant colonial ciliate Zoothamnium niveum and its vertically transmitted, nutritional, thiotrophic symbiont from an unstable environment of degrading wood. Previously, we have shown that sulphidic conditions lead to high host fitness and oxic conditions to low fitness, but the fate of the symbiont has not been studied. We combine several experimental approaches to provide evidence for a sulphide-tolerant host with striking polyphenism involving two discrete morphs, a symbiotic and an aposymbiotic one. The two differ significantly in colony growth form and fitness. This polyphenism is triggered by chemical conditions and elicited by the symbiont's presence on the dispersing swarmer. We provide evidence of a single aposymbiotic morph found in nature. We propose that despite a high fitness loss when aposymbiotic, the ciliate has retained a facultative life style and may use the option to live without its symbiont to overcome spatial and temporal shortage of sulphide in nature.

A study on the non-monophyletic genera Australothrix and Holostichides based on multigene and morphological analyses with a reexamination of type materials (Protozoa: Ciliophora).

In a study of ciliate diversity, we collected two new species of the genera Australothrix and Holostichides. Based on nuclear ribosomal genes, our study shows that these two genera are genetically non-monophyletic. To clarify the issues of the non-monophyly, we reexamined type material of H. heterotypicus, H. terrae, and Birojimia soyaensis. Based on multigene and morphometric analyses, Australothrix and Holostichides are clearly non-monophyletic even in mitochondrial CO1 gene trees. The multigene analyses show a clade composed of A. lineae sp. nov., H. terrae, and B. soyaensis, suggesting that a cytopharynx with argyrophilic structures might be their synapomorphy. A list of species with this type of cytopharynx is provided for further studies to either accept or reject this hypothesis. Based on the reexamination, we discriminate the morphologically nearly identical (cryptic/sibling) species H. obliquocirratus sp. nov. from H. heterotypicus and they show significant genetic dissimilarities in the multigene trees. They showed only few morphological (non-quantitative) differences and thus distinguishing them morphologically needs careful investigation.

Phylogeny of the ciliate family Psilotrichidae (Protista, Ciliophora), a curious and poorly-known taxon, with notes on two algae-bearing psilotrichids from Guam, USA.

BACKGROUND: The classification of the family Psilotrichidae, a curious group of ciliated protists with unique morphological and ontogenetic features, is ambiguous and poorly understood particularly due to the lack of molecular data. Hence, the systematic relationship between this group and other taxa in the subclass Hypotrichia remains unresolved. In this paper the morphology and phylogenetics of species from two genera of Psilotrichida are studied to shed new light on the phylogeny and species diversity of this group of ciliates. RESULTS: The 18S rRNA gene sequences of species from two psilotrichid genera were obtained. In the phylogenetic trees, the available psilotrichid sequences are placed in a highly supported clade, justifying the establishment of the family Psilotrichidae. The morphology of two little-known species, packed with green algae, including a new species, Hemiholosticha kahli nov. spec., and Psilotrichides hawaiiensis Heber et al., 2018, is studied based on live observation, protargol impregnation, and scanning electron microscopy. Both species are easily recognized by their green coloration due to the intracellular algae, and a comprehensive discussion as to the possible roles of the intracellular algae is provided. CONCLUSIONS: The 18S rRNA gene phylogeny supports the morphological argument that Hemiholosticha, Psilotrichides and Urospinula belong to the same family, Psilotrichidae. However, the single-gene analysis, not surprisingly, does not resolve the deeper relationships of Psilotrichidae within the subclass Hypotrichia. Two little-known psilotrichid genera with green algae were collected from the same puddle on the island of Guam, indicating a high species diversity and broader geographic distribution of this group of ciliates than previously supposed. Phylogenetic inferences from transcriptomic and/or genomic data will likely be necessary to better define the systematic position and evolution of the family Psilotrichidae. Further studies are also needed to clarify the role of the intracellular eyespot-bearing algae in these ciliates.

Glycine Betaine and Ectoine Are the Major Compatible Solutes Used by Four Different Halophilic Heterotrophic Ciliates.

One decisive factor controlling the distribution of organisms in their natural habitats is the cellular response to environmental factors. Compared to prokaryotes, our knowledge about salt adaptation strategies of microbial eukaryotes is very limited. We, here, used a recently introduced approach (implementing proton nuclear magnetic resonance spectroscopy) to investigate the presence of compatible solutes in halophilic, heterotrophic ciliates. Therefore, we isolated four ciliates from solar salterns, which were identified as Cyclidium glaucoma, Euplotes sp., Fabrea salina, and Pseudocohnilembus persalinus based on their 18S rRNA gene signatures and electron microscopy. The results of 1H-NMR spectroscopy revealed that all four ciliates employ the "low-salt-in" strategy by accumulating glycine betaine and ectoine as main osmoprotectants. We recorded a linear increase of these compatible solutes with increasing salinity of the external medium. Ectoine in particular stands out as its use as compatible solute was thought to be exclusive to prokaryotes. However, our findings and those recently made on two other heterotroph species call for a re-evaluation of this notion. The observation of varying relative proportions of compatible solutes within the four ciliates points to slight differences in haloadaptive strategies by regulatory action of the ciliates. Based on this finding, we provide an explanatory hypothesis for the distribution of protistan diversity along salinity gradients.

Association of Epistylis spp. (Ciliophora: Peritrichia) with parasitic crustaceans in farmed piava Megaleporinus obtusidens (Characiformes: Anostomidae).

Parasitic diseases have caused significant problems to global aquaculture production. These studies will further our knowledge of this complex problem and help implement adequate prevention measures and control strategies. The present study aimed to investigate the presence of parasites in Megaleporinus obtusidens and to describe the epidemiology and pathology of parasitic infections in these fish. Five moribund fish were sent for parasitological examination. The integument and gills were scrapped off with a glass slide, and samples were examined under a light microscope. Parasitic crustaceans found in these specimens were submitted for scanning electron microscopy and histological analyses. The crustaceans Dolops carvalhoi and Lernaea cyprinacea and the Epistylis spp. were present in all fish examined. Epistylis spp. were also seen on the entire surface of the crustacean integument. Microscopic lesions observed in the parasitized gills included hyperplasia and hypertrophy of the lamellar epithelium, an inflammatory infiltrate, telangiectasia, foci of hemorrhage and necrosis, fusion of the secondary lamellae, and detachment of the lamellar epithelium. Crustacean parasites are important mechanical vectors of Epistylis infection and disseminate the disease in fish farming operations. Epistylis spp. infection affects the health of fish and has significant ecological and economical impact on aquaculture.

Ultrastructure of vegetative cells and resting cysts, and live observations of the encystation and excystation processes in Diophrys oligothrix Borror, 1965 (Protista, Ciliophora).

Ciliated protists can form cysts to resist unfavorable environmental conditions and then excyst when environmental conditions become favorable. This study used electron and light microscopy to investigate the structure of vegetative cells and resting cysts, as well as the encysting and excysting processes of Diophrys oligothrix. For the first time, ampules were revealed beneath the pellicle in the genus Diophrys, and their extrusome types differed between Diophrys species. Membrane-packed discs of diverse shapes were found in the cytoplasm just beneath the pellicle around the cytopharynx and were separated by rows of microtubule units. Beneath the discs, some double-layer microtubule structures were detected as well. During encystment, the ventral ciliature was folded in a ventral cavity of the cell, and the caudal cirri were retracted directly into the cyst in a separate cavity on the dorsal side. In the resting cysts, high autophagic activity occurred, possibly including digestion of membrane-packed discs and ampules. Two macronuclear nodules kept their basic shape, although the chromatin aggregation and fusion region were observed in ultrathin sections. The cyst wall contained two layers, namely, the ectocyst, and endocyst. In mature cysts, basal bodies and ciliary shafts were observed, demonstrating that D. oligothrix forms non-kinetosome-resorbing cysts. The process of excystment occurred in two modes, either with or without participation of a contractile vacuole.

Association of Epistylis spp. (Ciliophora: Peritrichia) with parasitic crustaceans in farmed piava Megaleporinus obtusidens (Characiformes: Anostomidae) / Associação de Epistylis spp. (Ciliophora: Peritrichia) com crustáceos parasitas em piava Megaleporinus obtusidens de cultivo (Characiformes: Anostomidae)

Abstract Parasitic diseases have caused significant problems to global aquaculture production. These studies will further our knowledge of this complex problem and help implement adequate prevention measures and control strategies. The present study aimed to investigate the presence of parasites in Megaleporinus obtusidens and to describe the epidemiology and pathology of parasitic infections in these fish. Five moribund fish were sent for parasitological examination. The integument and gills were scrapped off with a glass slide, and samples were examined under a light microscope. Parasitic crustaceans found in these specimens were submitted for scanning electron microscopy and histological analyses. The crustaceans Dolops carvalhoi and Lernaea cyprinacea and the Epistylis spp. were present in all fish examined. Epistylis spp. were also seen on the entire surface of the crustacean integument. Microscopic lesions observed in the parasitized gills included hyperplasia and hypertrophy of the lamellar epithelium, an inflammatory infiltrate, telangiectasia, foci of hemorrhage and necrosis, fusion of the secondary lamellae, and detachment of the lamellar epithelium. Crustacean parasites are important mechanical vectors of Epistylis infection and disseminate the disease in fish farming operations. Epistylis spp. infection affects the health of fish and has significant ecological and economical impact on aquaculture.

Resumo Doenças parasitárias causam problemas significativos a produção mundial de peixes. Esse estudo aprofundará nosso conhecimento neste complexo problema e ajudará implementar estratégias de prevenção e controle. O objetivo deste trabalho foi analisar os parasitas encontrados em Megaleporinus obtusidens de piscicultura extensiva e descrever as relações epidemiológicas e patológicas entre eles. Cinco peixes moribundos foram enviados para análise parasitológica. O tegumento e as brânquias foram raspados com lâminas de vidro e examinados em microscópio óptico. Os crustáceos parasitas foram processados para análises histologicas e de microscopia eletrônica de varredura. Todos os peixes analisados foram infestados pelos crustáceos Dolops carvalhoi, Lernaea cyprinacea e pelo Epistylis spp. Epistylis spp. foram também encontrados na superfície de todo tegumento dos crustáceos parasitas. As brânquias parasitadas apresentaram hiperplasia e hipertrofia do epitélio lamelar, infiltrado inflamatório, telangectasia, focos hemorrágicos e necróticos, extensas áreas com fusão de lamelas secundárias e desprendimento de epitélio lamelar. Os crustáceos parasitas são vetores mecânicos importantes da epistilíase, disseminando o microorganismo nas criações de peixes. A infestação por Epistylis spp. afeta a saúde dos peixes e tem impacto ecológico e econômico significativo na aquacultura.

Sicuophora (Syn. Wichtermania) multigranularis from Quasipaa spinosa (Anura): morphological and molecular study, with emphasis on validity of Sicuophora (Armophorea, Clevelandellida).

Morphological studies of Sicuophora (Syn. Wichtermania) multigranularis Xiao et al., 2002, from the rectum of the frog, Quasipaa spinosa, performed using silver impregnation and scanning electron microscopy, confirmed the following newly recognized features: (1) only one apical suture on the right surface; (2) two naked regions at the posterior end of both the left and the right side of the body. Phylogenetic analysis based on the SSU-rRNA gene showed that S. multigranularis is a sister to a clade comprising all other Clevelandellida, strongly supporting the validity of the genus Sicuophora. This is also the first molecular data obtained for the genus Sicuophora. Because of the lack of molecular data, it will be necessary to obtain more genetic data from the family Sicuophoridae to discuss the question of the taxonomic status of the genus Sicuophora.

The Little-known Freshwater Metopid Ciliate, Idiometopus turbo (Dragesco and Dragesco-Kernéis, 1986) nov. gen., nov. comb., Originally Discovered in Africa, Found on the Micronesian Island of Guam.

Class Armophorea Lynn, 2004 includes two orders of mainly free-living anaerobic ciliates, Armophorida Jankowski, 1980 and Metopida Jankowski, 1980 and, a third, the exclusively endosymbiotic Clevelandellida. Kahl described the majority of free-living metopid species early in the 20th century. Excepting Jankowski in the 1960's, little further interest was shown in this group. Metopus turbo Dragesco and Dragesco-Kernéis, 1986, from a West African pond, was more recently described. Although not explicitly described as endemic, Dragesco believed in some degree of endemism of sub-Saharan ciliates. Our discovery of M. turbo on Guam, Micronesia was unexpected. Metopus turbo was identified by live observation, protargol impregnation, and scanning electron microscopy, providing reasonable evidence of conspecificity when compared with the original description. Outstanding morphologic features include the stout shape and transversely situated bandform macronucleus. The morphology of Metopus turbo differs markedly from that of the Metopus/Brachonella clade and is distant from Metopus es in phylogenetic analyses. The 18S rDNA sequence of the Guam M. turbo differs from that of M. es, type species of Metopus, by >8% and shows distinct morphologic differences from the genus Atopospira to which it is sister. These facts suggest that transfer to a new genus, Idiometopus gen. nov. is indicated.