Epibiotic ciliate communities on the crayfish Procambarus (Austrocambarus) sp. cultivated in a rustic aquaculture in southern Mexico.

Rustic aquaculture systems represent a sustainable production alternative in the world, providing appropriate conditions for the establishment of epibiotic ciliates on crayfish. However, the impact of epibiotic ciliates on the aquaculture production has been insufficiently studied hitherto. The objective of this work was to identify the epibiotic ciliates on the surface of the crayfish Procambarus (Austrocambarus) sp. and analyze whether there is any correlation between seasonality and environmental conditions in an artificial pond in Chiapas, Mexico. The crayfish were collected during dry and rainy seasons to investigate their ciliate epibionts. Some physical and chemical parameters of the sampled water were measured and correlation matrix analyses were applied to detect possible relationships between the presence of ciliates and environmental parameters. Thirteen species belonging to the subclasses Peritrichia and Suctoria were identified. Significant differences were found for some environmental parameters and species recorded in both seasons. The present data could help to better understand the relationship bewteen the epibiotic ciliate community on crayfish and some environmental parameters in aquaculture systems.

Ciliate diversity in rodrigo de freitas lagoon (Rio de Janeiro, Brazil) from an integrative standpoint.

The Rodrigo de Freitas Lagoon is a highly eutrophic lacustrine system and has one of the longest histories of exploration and anthropic alteration in Brazil. Despite its relevance, limited studies explored the diversity of micro-eukaryotes in the lagoon. Ciliates (Alveolata, Ciliophora) are overlooked in environmental microbiology, especially in tropical and subtropical ecosystems, resulting in limited knowledge about their diversity and functional relevance in South American habitats, particularly in coastal lagoons. To fill this gap, here we investigated the diversity of ciliates in a brackish coastal lagoon in an urban area of Rio de Janeiro, Brazil, applying and comparing the performance of morphological and metabarcoding approaches. The metabarcoding analysis, based on high-throughput sequencing of the hipervariable region V4 of the 18S rRNA genes detected 37 molecular operational taxonomic units (MOTUs) assigned to Ciliophora, representing only about a half (56.9%) of the diversity detected by microscopy, which counted 65 ciliate morphotypes. The most representative classes in both approaches were Spirotrichea and Oligohymenophorea. The metabarcoding analysis revealed that 35.3% of the ciliate MOTUs had less than 97% similarity to available sequences in the NCBI database, indicating that more than one-third of these MOTUs potentially represents still not represented or undescribed ciliate species in current databases. Our findings indicate that metabarcoding techniques can significantly enhance the comprehension of ciliate diversity in tropical environments, but the scarcity of reference sequences of brackish ciliates in molecular databases represents a challenge to the taxonomic assignment of the MOTUs. This study provides new insights into the diversity of ciliates in a threatened coastal lagoon, revealing a vast array of still unknown and rare ciliate taxonomic units in tropical environments.

In silico characterization of cysteine-stabilized αß defensins from neglected unicellular microeukaryotes.

BACKGROUND: The emergence of multi-resistant pathogens have increased dramatically in recent years, becoming a major public-health concern. Among other promising antimicrobial molecules with potential to assist in this worldwide struggle, cysteine-stabilized αß (CS-αß) defensins are attracting attention due their efficacy, stability, and broad spectrum against viruses, bacteria, fungi, and protists, including many known human pathogens. RESULTS: Here, 23 genomes of ciliated protists were screened and two CS-αß defensins with a likely antifungal activity were identified and characterized, using bioinformatics, from a culturable freshwater species, Laurentiella sp. (LsAMP-1 and LsAMP-2). Although any potential cellular ligand could be predicted for LsAMP-2; evidences from structural, molecular dynamics, and docking analyses suggest that LsAMP-1 may form stably associations with phosphatidylinositol 4,5-bisphosphates (PIP2), a phospholipid found on many eukaryotic cells, which could, in turn, represent an anchorage mechanism within plasma membrane of targeted cells. CONCLUSION: These data stress that more biotechnology-oriented studies should be conducted on neglected protists, such ciliates, which could become valuable sources of novel bioactive molecules for therapeutic uses.

Molecular characterization of waterborne protozoa in surface water and sediment in Brazil: a taxonomic survey of ciliated protozoa and their correlation with Giardia duodenalis and Cryptosporidium spp.

The detection of Giardia duodenalis and Cryptosporidium spp. was performed, along with the identification of the ciliated protozoa biodiversity, to evaluate the correlation between these protozoa in freshwater quality monitoring. Water and sediment samples from two sites in the Atibaia River (Campinas, São Paulo, Brazil) were collected monthly for 2 years (n = 96). Pathogenic protozoa in water and sediment were detected by using immunomagnetic separation, followed by visualization by immunofluorescence assay (IFA). All positive aliquots in IFA were subjected to DNA extraction and subsequently nested PCR. Qualitative (in vivo observation and silver impregnation) and quantitative (in vivo enumeration) analyses were performed for the ciliated protozoa. Giardia cysts were detected in 62.5% of the surface water samples and Cryptosporidium spp. in 25.0%. In the sediment, cysts were detected in 35.4% samples and oocysts in 16.6%. A total of 57 samples positive for Giardia cysts were subjected to sequencing, 40 of which were harboring G. duodenalis (24 were characterized as sub-assemblage AII). For ciliated protozoa, 73 taxa belonging to 53 genera were identified over the period of the study. These results revealed a high degree of contamination by waterborne protozoa in the main water source which supplies drinking water for more than one million people in Campinas (São Paulo), highlighting the need for continuous monitoring of this catchment site. In addition, the present study provides important data regarding the sources of the water body degradation, i.e., fecal contamination of human origin, in addition to the survey of the ciliated protozoa.

Structure and Dynamics of Periphyton in a Neotropical Freshwater Lake, with Emphasis on Ciliates and Their Relationships with Bacterial Taxa.

Periphyton communities in freshwater systems play an essential role in biogeochemical processes, but knowledge of their structure and dynamics lags far behind other environments. We used eDNA metabarcoding of 16S and 18S rRNA markers to investigate the formation and establishment of a periphytic community, in addition to a morphology-based approach for peritrich ciliate determinations, its most abundant group. We sampled two nearby sites within a large Neotropical lake at four time points, aiming to assess whether periphyton establishment can be replicated on this local scale. Producers and denitrifiers were abundant in the community, illustrating the relevant role of biofilms in freshwater nutrient recycling. Among microeukaryotes, peritrich ciliates dominated the community, with genera Epistylis and Vorticella being the most abundant and showing a clear succession at both sites. Other ciliates were morphologically identified and, in some cases, their occurrence was strongly related to bacterial abundance. The structure of both prokaryotic and eukaryotic components of periphyton was not different, while the turnover dynamics differed between the two sites, in spite of their adjacent locations and similar abiotic properties. This indicates that the establishment of these communities can vary even on a local scale within a lake ecosystem.

Evaluation of five parasitological techniques for diagnosing phylum Ciliophora cysts in fecal samples from free-living wild artiodactyls / Avaliação de cinco técnicas parasitológicas para o diagnóstico de cistos do filo Ciliophora em amostras fecais de artiodáctilos silvestres em vida livre

A variety of laboratory techniques are used in parasitological diagnosis. However, studies that analyze their laboratory efficiency are very scarce, especially with regard to biological samples from wild animals that are little known, with little popular attachment, such as artiodactyls. These can be infected by different parasites, including protozoa of the phylum Ciliophora, which includes the parasites Balantioides coli and Buxtonella sulcata. In this light, the aim of this study was to compare the efficiency of five coproparasitological techniques for diagnosing protozoan cysts of the phylum Ciliophora in the feces of free-living artiodactyls. To this end, 101 fecal samples were collected from trails in Pedra Selada State Park, Rio de Janeiro state, from 2020 to 2021. All the samples were analyzed using the qualitative techniques of modified Sheather floatation, modified Ritchie sedimentation and Lutz, as well as the quantitative techniques of Mini-FLOTAC and McMaster. Cyst recovery was best achieved using the modified Ritchie technique, in which 62.5% positivity was detected, followed by Lutz (47.5%), modified Sheather (37.5%) and the quantitative techniques of Mini-FLOTAC (30%) and McMaster (17.5%). In most of the comparisons between the techniques, reasonable agreement regarding the diagnosis was observed (Kappa 0.21 to 0.40), which was statistically significant (p≤0.05). McMaster showed higher mean and standard deviation values for counts of cysts per gram of feces than Mini-FLOTAC. However, there was no significant difference in the estimates for cyst counts (Wilcoxon p>0.05). Sedimentation qualitative techniques were more indicated for diagnosing cysts of protozoa of the phylum Ciliophora in the feces of free-living wild artiodactyls. These techniques can therefore be used as laboratory tools for environmental parasite monitoring. In addition, between the two quantitative techniques, Mini-FLOTAC presented better performance, thus showing its potential as a tool for estimating the abundance of cystic forms of the phylum Ciliophora in environmental samples.

Diversas são as técnicas laboratoriais utilizadas no diagnóstico parasitológico. No entanto, estudos que analisam a eficiência laboratorial das mesmas são muito escassos, principalmente quando se trata de amostras biológicas de animais silvestres, que possuem pouca divulgação e apego popular, como os artiodáctilos. Estes podem se infectar por diferentes parasitos, incluindo os protozoários do Filo Ciliophora, no qual se inclui Balantioides coli, bem como Buxtonella sulcata. Mediante o exposto, este estudo objetivou comparar a eficiência entre cinco técnicas coproparasitológicas para o diagnóstico de cistos de protozoário do Filo Ciliophora em fezes de artiodáctilos em vida livre. Entre 2020 e 2021 foram coletadas 101 amostras fecais em trilhas do Parque Estadual da Pedra Selada localizado no estado do Rio de Janeiro. Todas as amostras foram analisadas pelas técnicas qualitativas de flutuação de Sheather modificada, sedimentação de Ritchie modificada e Lutz, bem como por meio das técnicas quantitativas de Mini-FLOTAC e McMaster. Pode-se verificar uma superioridade na recuperação dos cistos por meio da técnica de Ritchie modificada, no qual foi detectado 62,5% de positividade, seguida pelo Lutz (47,5%), Sheather modificada (37,5%) e pelas técnicas quantitativas de Mini-FLOTAC (30%) e McMaster (17,5%). Na maioria das comparações entre as técnicas foi possível verificar uma concordância razoável (Kappa 0,21 a 0,40) em relação ao diagnóstico entre as mesmas, sendo este estatisticamente significativo (p≤0,05). McMaster em comparação com o Mini-FLOTAC foi a que apresentou os maiores valores médio e de desvio padrão na contagem dos cistos por grama de fezes. No entanto, não foi evidenciado diferença significativa na estimativa de contagem dos cistos (Wilcoxon=p>0,05). Pode-se verificar que as técnicas qualitativas de sedimentação foram consideradas as mais indicadas para o diagnóstico de cistos do protozoário do Filo Ciliophora em fezes de artiodáctilos silvestres em vida livre, podendo ser utilizadas como ferramentas laboratoriais de monitoramento parasitário ambiental. Além disso, dentre as técnicas quantitativas, o Mini-FLOTAC foi a que apresentou a melhor performance, denotando o seu potencial como uma ferramenta para se estimar a abundância de formas císticas do Filo Ciliophora em amostra ambiental.

Macroevolutionary analyses of ciliates associated with hosts support high diversification rates.

Ciliophora is a phylum that is comprised of extremely diverse microorganisms with regard to their morphology and ecology. They may be found in various environments, as free-living organisms or associated with metazoans. Such associations range from relationships with low metabolic dependence such as epibiosis, to more intimate relationships such as mutualism and parasitism. We know that symbiotic relationships occur along the whole phylogeny of the group, however, little is known about their evolution. Theoretical studies show that there are two routes for the development of parasitism, yet few authors have investigated the evolution of these characteristics using molecular tools. In the present study, we inferred a wide dated molecular phylogeny, based on the 18S rDNA gene, for the entire Ciliophora phylum, mapped life habits throughout the evolutionary time, and evaluated whether symbiotic relationships were linked to the variation in diversification rates and to the mode of evolution of ciliates. Our results showed that the last common ancestor for Ciliophora was likely a free-living organism, and that parasitism is a recent adaptation in ciliates, emerging more than once and independently via two distinct routes: (i) a free-living ciliate evolved into a mutualistic organism and, later, into a parasitic organism, and (ii) a free-living ciliate evolved directly into a parasitic organism. Furthermore, we have found a significant increase in the diversification rate of parasitic and mutualistic ciliates compared with their free-living conspecifics. The evolutionary success in different lineages of symbiont ciliates may be associated with many factors including type and colonization placement on their host, as well as physical and physiological conditions made available by the hosts.

Ciliates as bioindicators of water quality: A case study in the neotropical region and evidence of phylogenetic signals (18S-rDNA).

The aim of our study was to evaluate the water quality of an urban stream in southeastern Brazil by analyzing epibenthic ciliates, and to investigate the existence of phylogenetic signal for saprobity in ciliates. However, before conducting this type of phylogenetic study, it is necessary to evaluate if the saprobic classification used frequently in the northern Hemisphere is suitable for neotropical ecosystems. Sediment samples were collected from five sampling stations: two in rural areas and three in urban areas. During the one-year study, with monthly collections, 39 ciliates species were found, of which 32 are included in the saprobic system. Physical, chemical and biological parameters of water confirm the spatial heterogeneity of the sampling stations, with a clear influence of organic pollution on the composition and structure of ciliates taxocenosis. The saprobic index and the saprobic valence index were used to evaluate the water quality of the sampling stations and demonstrated clear heterogeneity between the stations and high degree of pollution of the urban area. These sampling stations were dominated by ciliates indicators of polysaprobric environments. Since we were able to successfully use the saprobic index in a limnic ecosystem in Brazil, we applied the phylogenetic signal validation as a tool for saprobity prediction of the limnic ciliate species not yet analyzed. A phylogenetic tree containing only 18S-rDNA nominal sequences of freshwater ciliates was estimated and used to explore the existence of the phylogenetic signal, which showed that the sensitivity/tolerance of ciliates to organic pollution reflected evolutionary divergence. The results confirm the existence of phylogenetic signal for the saprobrity in Ciliophora. Also, our results suggest that evolutionary analysis is a potential method to predict lineages of ciliates not yet classified for saprobity.

A new species of Uronychia (Spirotrichea: Euplotida) from Argentina.

Uronychia clapsae sp. n. was discovered in an artificial channel that drains an endorheic area from the "sandy Pampa" into the upper basin of Salado River, Buenos Aires, Argentina. This euplotid measures 56-112 µm × 42-70 µm in vivo, is oval in shape and the buccal field is enormous, occupying ca. 80% of body length. It is characterized by having two macronuclear nodules and one micronucleus; usually 10 anterior and invariably three posterior membranelles; right end of paroral hook-like; buccal cirrus base about 3.5-6.0 µm long; invariably four frontal, two ventral, three left marginal, four transverse, and three caudal cirri; six dorsal kineties, kinety 1 with 15-22 dikinetids. Most Uronychia species were recorded in marine habitats, while this new isolate was found in a slightly saline, inland water body. Taxonomic and nomenclatorial concerns on some species assigned to Uronychia are also discussed.

SSU-rRNA Gene Sequencing Survey of Benthic Microbial Eukaryotes from Guaymas Basin Hydrothermal Vent.

Microbial eukaryotes have important roles in marine food webs, but their diversity and activities in hydrothermal vent ecosystems are poorly characterized. In this study, we analyzed microbial eukaryotic communities associated with bacterial (Beggiatoa) mats in the 2,000 m deep-sea Guaymas Basin hydrothermal vent system using 18S rRNA gene high-throughput sequencing of the V4 region. We detected 6,954 distinct Operational Taxonomic Units (OTUs) across various mat systems. Of the sequences that aligned with known protistan phylotypes, most were affiliated with alveolates (especially dinoflagellates and ciliates) and cercozoans. OTU richness and community structure differed among sediment habitats (e.g. different mat types and cold sediments away from mats). Additionally, full-length 18S rRNA genes amplified and cloned from single cells revealed the identities of some of the most commonly encountered, active ciliates in this hydrothermal vent ecosystem. Observations and experiments were also conducted to demonstrate that ciliates were trophically active and ingesting fluorescent bacteria or Beggiatoa trichomes. Our work suggests that the active and diverse protistan community at the Guaymas Basin hydrothermal vent ecosystem likely consumes substantial amounts of bacterial biomass, and that the different habitats, often defined by distances of just a few 10s of cm, select for particular assemblages and levels of diversity.

Protist Biodiversity and Biogeography in Lakes From Four Brazilian River-Floodplain Systems.

The biodiversity and biogeography of protists inhabiting many ecosystems have been intensely studied using different sequencing approaches, but tropical ecosystems are relatively under-studied. Here, we sampled planktonic waters from 32 lakes associated with four different river-floodplains systems in Brazil, and sequenced the DNA using a metabarcoding approach with general eukaryotic primers. The lakes were dominated by the largely free-living Discoba (mostly the Euglenida), Ciliophora, and Ochrophyta. There was low community similarity between lakes even within the same river-floodplain. The protists inhabiting these floodplain systems comprise part of the large and relatively undiscovered diversity in the tropics.

Diversity of freshwater ciliates (Protista) from Argentina

Diversity of ciliates from freshwater and soil were scarcely investigated in Argentina, in spite of their ecological role in these ecosystems and the huge environmental heterogeneity that can be found in this country. In the present study, we describe the morphology of nine species from a temporary pond in Buenos Aires province, by means of live observations and protargol impregnations. Stentor igneus Ehrenberg, Pseudochilodonopsis piscatoris (Blochmann), Vorticella halophila Stiller, Intranstylum invaginatum Stokes, and Epistylis rotans vec were recorded for the first time in Argentina, and in most cases, are new for the Neotropical realm as well. In addition, an updated checklist on freshwater ciliates from Argentina is provided, based on ciliates listed for the Salado River basin in the Buenos Aires province, new findings from Rancho Hambre peat bog pools in Tierra del Fuego province and a pond from Misiones province.

Checklist of ciliated protozoa from surface water and sediment samples of Atibaia River, Campinas, São Paulo (Southeast Brazil)

The knowledge of the diversity of ciliated protozoa in an aquatic ecosystem is an important information that can serve as a tool in the environmental quality management. A survey of the ciliated protozoa of the Atibaia River, Campinas, São Paulo was done during 24 months. Surface water and sediment samples were collected monthly from two sampling points. Qualitative analyses of ciliates were performed in vivo and by protargol staining. A total of 66 taxa belonging to 55 genera were identified. This is the first study in Atibaia River and, as this is an impacted water body, these informations can be very useful for conservation.

First report of an epibiotic relationship between ciliates and planktonic copepods in a Brazilian floodplain

The peritrich ciliates are a widely distributed group of protozoa and include stalked and sedentary organisms, which may be solitary or colonial. These organisms are often observed as part of a relationship entitled epibiosis. This relationship is a facultative association between two organisms: the epibiont, which colonizes the surface of living substrates, and the basibiont, which hosts the epibionts. During a survey on the epibiotic relationship between ciliates e copepods in upper Paraná River floodplain-PR/MS Brazil, samples were taken in different types of environments (three rivers, three canals, 16 connected and 14 unconnected lakes), in a total of 36 sampling sites. Among these environments, 22 showed copepods infested by epibiont ciliates. The copepods Thermocyclops decipiens, Thermocyclops minutus and Notodiaptomus amazonicuswhere colonized by epibiont ciliates from the genus Epistylis.In this study, we reported for the first time, epibiosis in a Brazilian floodplain.

Improved silver carbonate impregnation method for rumen ciliate protozoa

This study proposes improvements to the pyridinated silver carbonate impregnation technique in rumen ciliate protozoa in order to provide a standardized impregnation protocol for usable for the largest possible number of species in domestic ruminants. The proposed improvements are based on results obtained from impregnation of oral infraciliature and nuclear apparatus of 36 rumen ciliate species, which are symbionts of domestic ruminants. Compared to established protocols for morphology of rumen ciliates, impregnation of a wider range of genera and species was observed with the proposed protocol. The impregnation time varied according to size, ciliate taxon, or both, varying from shorter (5 minutes) for small entodiniomorphid ciliates ( 80 m) and the genus Dasytricha, to longer (30 minutes) for large entodiniomorphid ciliates (>80 m) and the genus Isotricha. The proposed protocol is simple and easily reproducible. It is also advantageous for taxonomic, animal science, and ecological studies that aim to inventory the ruminal biota as well as understand the population structure of rumen ciliates and their relationship with the host.

Diversity of freshwater ciliates (Protista) from Argentina

Diversity of ciliates from freshwater and soil were scarcely investigated in Argentina, in spite of their ecological role in these ecosystems and the huge environmental heterogeneity that can be found in this country. In the present study, we describe the morphology of nine species from a temporary pond in Buenos Aires province, by means of live observations and protargol impregnations. Stentor igneus Ehrenberg, Pseudochilodonopsis piscatoris (Blochmann), Vorticella halophila Stiller, Intranstylum invaginatum Stokes, and Epistylis rotans vec were recorded for the first time in Argentina, and in most cases, are new for the Neotropical realm as well. In addition, an updated checklist on freshwater ciliates from Argentina is provided, based on ciliates listed for the Salado River basin in the Buenos Aires province, new findings from Rancho Hambre peat bog pools in Tierra del Fuego province and a pond from Misiones province.(AU)

Checklist of ciliated protozoa from surface water and sediment samples of Atibaia River, Campinas, São Paulo (Southeast Brazil)

The knowledge of the diversity of ciliated protozoa in an aquatic ecosystem is an important information that can serve as a tool in the environmental quality management. A survey of the ciliated protozoa of the Atibaia River, Campinas, São Paulo was done during 24 months. Surface water and sediment samples were collected monthly from two sampling points. Qualitative analyses of ciliates were performed in vivo and by protargol staining. A total of 66 taxa belonging to 55 genera were identified. This is the first study in Atibaia River and, as this is an impacted water body, these informations can be very useful for conservation.(AU)

First report of an epibiotic relationship between ciliates and planktonic copepods in a Brazilian floodplain

The peritrich ciliates are a widely distributed group of protozoa and include stalked and sedentary organisms, which may be solitary or colonial. These organisms are often observed as part of a relationship entitled epibiosis. This relationship is a facultative association between two organisms: the epibiont, which colonizes the surface of living substrates, and the basibiont, which hosts the epibionts. During a survey on the epibiotic relationship between ciliates e copepods in upper Paraná River floodplain-PR/MS Brazil, samples were taken in different types of environments (three rivers, three canals, 16 connected and 14 unconnected lakes), in a total of 36 sampling sites. Among these environments, 22 showed copepods infested by epibiont ciliates. The copepods Thermocyclops decipiens, Thermocyclops minutus and Notodiaptomus amazonicuswhere colonized by epibiont ciliates from the genus Epistylis.In this study, we reported for the first time, epibiosis in a Brazilian floodplain.(AU)

Improved silver carbonate impregnation method for rumen ciliate protozoa

This study proposes improvements to the pyridinated silver carbonate impregnation technique in rumen ciliate protozoa in order to provide a standardized impregnation protocol for usable for the largest possible number of species in domestic ruminants. The proposed improvements are based on results obtained from impregnation of oral infraciliature and nuclear apparatus of 36 rumen ciliate species, which are symbionts of domestic ruminants. Compared to established protocols for morphology of rumen ciliates, impregnation of a wider range of genera and species was observed with the proposed protocol. The impregnation time varied according to size, ciliate taxon, or both, varying from shorter (5 minutes) for small entodiniomorphid ciliates ( 80 m) and the genus Dasytricha, to longer (30 minutes) for large entodiniomorphid ciliates (>80 m) and the genus Isotricha. The proposed protocol is simple and easily reproducible. It is also advantageous for taxonomic, animal science, and ecological studies that aim to inventory the ruminal biota as well as understand the population structure of rumen ciliates and their relationship with the host.(AU)

Trichodina modesta: an exotic ciliate in the Neotropical region parasitizing an unusual host / Trichodina modesta: exótico ciliado na região Neotropical parasitando hospedeiro não usual

In this study, an important ornamental fish, Betta splendens (Osphronemidae), from three different Brazilian states was examined for parasitic infestations. Smears with parasites were impregnated with silver nitrate or stained using Giemsa for taxonomic evaluation. A disc-shaped trichodinid with a body diameter of 39.7 ± 3.3 µm, adhesive disc diameter of 32.9 ± 3.1 µm and denticulate ring diameter of 19.5 ± 2.0 µm was found. The morphological characteristics resembled those of Trichodina modesta Lom, 1970, a species that shows clear host specificity for Cypriniformes. Until now, its occurrence was restricted to the Eurasian region. In the present study, a new host for T. modesta is reported and therefore the first occurrence of this species in the Americas. The parasite was possibly introduced into the Neotropical region through the exotic fish trade, especially of Cypriniformes used by aquarists. The distribution of this ciliate is discussed and a checklist of localities and hosts for the species is provided.

Neste estudo, o peixe ornamental Betta splendens (Osphronemidae) foi examinado a partir de três diferentes Estados brasileiros para infestações parasitárias. Esfregaços contendo parasitos foram impregnados com nitrato de prata ou corados com Giemsa para avaliação taxonômica. Foi observado o tricodinídeo em forma de disco com 39,7 ± 3,3 µm de diâmetro do corpo, disco adesivo com 32,9 ± 3,1 µm e anel denticulado 19,5 ± 2,0 µm de diâmetro. As características morfológicas foram semelhantes à Trichodina modesta Lom, 1970, uma espécie que apresenta especificidade de hospedeiro por peixes Cypriniformes com ocorrência na Região Euro-asiática. No presente estudo, um novo hospedeiro para T. modesta é reportado, assim como a primeira ocorrência da espécie na América. O parasito tem sido possivelmente introduzido na região Neotropical com o comércio de peixes exóticos, principalmente Cypriniformes usados por aquariofilistas. A dispersão do ciliado é discutida e um “checklist” de localidades e hospedeiros apresentado.