Taxonomy and molecular phylogeny of a new freshwater ciliate Frontonia apoacuminata sp. nov. (Protista, Ciliophora, Oligohymenophorea) from Qingdao, PR China.

The morphology and ciliature of a new freshwater ciliate, Frontonia apoacuminata sp. nov., isolated from an artificial pond in Qingdao, PR China, were investigated using live observation and silver staining methods. The main features separating F. apoacuminata sp. nov. from its congeners are as follows: a broad elliptical body that is slightly pointed at the posterior end, four ophryokineties, one or two spherical micronuclei of a 'compact' type, a dorsally positioned contractile vacuole, and peniculi 1-3 each with five kinetosome rows though the left-most two rows in peniculus 3 are extremely shortened (with only two or three kinetosomes each). Additionally, an improved diagnosis of F. acuminata is provided. Phylogenetic analyses based on the small subunit ribosomal RNA (SSU rRNA) gene show that F. apoacuminata sp. nov. clusters with F. atra, F. minuta, F. acuminata and F. terricola. These five species group with Disematostoma, Marituja and Stokesia rather than with other Frontonia species, causing polyphyly of the genus Frontonia.

Molecular characterization and phylogenetic analyses of Tripartiella macrosoma Basson and Van As, 1987 and Tripartiella obtusa Ergens and Lom, 1970 based on 18S rRNA gene sequence data.

In the present study, we provided the first 18S rRNA gene sequence data of two Tripartiella species, Tripartiella macrosoma Basson and Van As, 1987 and Tripartiella obtusa Ergens and Lom, 1970, which were isolated from Tachysurus fulvidraco (Richardson, 1846) and Hemibarbus maculatus Bleeker, 1871 in Chongqing, China, respectively. Morphologically, both species fall within the morphometry range of the original descriptions and are very similar to the original populations in the overall appearance of the adhesive disc. Tripartiella macrosoma can be easily distinguished from the other Tripartiella species by possessing the denticle with a long strip and conspicuously inclined backward blade and a robust and short ray. Tripartiella obtusa is mainly characterized by a broad blade and a relatively long ray. Phylogenetically, T. macrosoma clustered with Trichodinella myakkae (Mueller, 1937) Raabe, 1950 and further with Trichodinella sp., which was sister to a group that includes four populations of Trichodinella epizootica (Raabe, 1950) Srámek-Husek, 1953; finally, they formed a small clade with T. obtusa. This result suggested that T. macrosoma had a closer relationship with Trichodinella spp. than with T. obtusa and T. obtusa diverged earlier than T. macrosoma and Trichodinella spp. By combining morphological and molecular data, the polyphyletic characteristics of Tripartiella and Trichodinella were further analyzed, and the results revealed that the validity of the genus Tripartiella is doubtful.

Incorporating mitogenome sequencing into integrative taxonomy: The multidisciplinary redescription of the ciliate Thuricola similis (Peritrichia, Vaginicolidae) provides new insights into the evolutionary relationships among Oligohymenophorea subclasses.

The evolutionary relationships among Oligohymenophorea subclasses are under debate as the phylogenomic analysis using a large dataset of nuclear coding genes is significantly different to the 18S rDNA phylogeny, and it is unfortunately not stable within and across different published studies. In addition to nuclear genes, the faster-evolving mitochondrial genes have also shown the ability to solve phylogenetic problems in many ciliated taxa. However, due to the paucity of mitochondrial data, the corresponding work is scarce, let alone the phylogenomic analysis based on mitochondrial gene dataset. In this work, we presented the characterization on Thuricola similis Bock, 1963, a loricate peritrich (Oligohymenophorea), incorporating mitogenome sequencing into integrative taxonomy. As the first mitogenome for the subclass Peritrichia, it is linear, 38,802 bp long, and contains two rRNAs, 12 tRNAs, and 43 open reading frames (ORFs). As a peculiarity, it includes a central repeated region composed of tandemly repeated A-T rich units working as a bi-transcriptional start. Moreover, taking this opportunity, the phylogenomic analyses based on a set of mitochondrial genes were also performed, revealing that T. similis, as a representative of Peritrichia subclass, branches basally to other three Oligohymenophorea subclasses, namely Hymenostomatia, Peniculia, and Scuticociliatia. Evolutionary relationships among those Oligohymenophorea subclasses were discussed, also in the light of recent phylogenomic reconstructions based on a set of nuclear genes. Besides, as a little-known species, T. similis was also redescribed and neotypified based on data from two populations collected from wastewater treatment plants (WWTPs) in Brazil and Italy, by means of integrative methods (i.e., living observation, silver staining methods, scanning and transmission electron microscopy, and 18S rDNA phylogeny). After emended diagnosis, it is characterized by: (1) the sewage habitat; (2) the lorica with a single valve and small undulations; (3) the 7-22 µm-long inner stalk; and (4) the presence of only a single postciliary microtubule on the left side of the aciliferous row in the haplokinety. Among Vaginicolidae family, our 18S rRNA gene-based phylogenetic analysis revealed that Thuricola and Cothurnia are monophyletic genera, and Vaginicola could be a polyphyletic genus.

Morphology and molecular analyses of four epibiotic peritrichs on crustacean and polychaete hosts, including descriptions of two new species (Ciliophora, Peritrichia).

Four epibiotic sessilid peritrichs, i.e., Zoothamnium wilberti n. sp., Baikalonis microdiscus n. sp., Epistylis anastatica (Linnaeus, 1767) Ehrenberg, 1830, and Rhabdostyla commensalisMöbius, 1888, were isolated from one syllid polychaete and three crustacean hosts in Qingdao, China. For each species, specimens were observed both in vivo and following silver staining. Their SSU rDNA was also sequenced for phylogenetic analyses. Zoothamnium wilberti n. sp. is characterized by the appearance of its colony, which is up to 350 µm high, and usually has fewer than 16 zooids, and the dichotomously branched stalk with transverse wrinkles, the conspicuously conical peristomial disc, and infundibular polykinety 3 comprising three isometric ciliary rows. Baikalonis microdiscus n. sp. can be recognized by its barrel-shaped zooid, small peristomial disc, smooth and short stalk, and its unusual infundibular polykinety 3 comprising a long inner row and a short outer row. Two poorly known species, i.e., Epistylis anastatica and Rhabdostyla commensalis, are redescribed and redefined. Phylogenetic analyses reveal that: (i) R. commensalis is closely related to the family Astylozoidae rather than to the morphologically similar Epistylididae; (ii) B. microdiscus n. sp. is sister to the family Scyphidiidae; (iii) E. anastatica groups with vorticellids and ophrydiids, which further supports the polyphyly of the genus Epistylis; and (iv) Z. wilberti n. sp. is nested within the Zoothamniidae, as expected.

First report of Trichodinella and new geographical records of trichodinids in Nile tilapia (Oreochromis niloticus) farmed in Brazil / Primeiro relato de Trichodinella e novos registros geográficos de tricodinídeos em tilapia do Nilo (Oreochromis niloticus) cultivada no Brasil

Abstract Massive occurrence of trichodinids is frequently accompanied by serious disease in fish farms. In this study, trichodinid species from the gills and skin of Nile tilapia (Oreochromis niloticus) farmed in the central-western region of Brazil (state of Goiás) were morphologically characterized. Dried slides were prepared from the parasites and were impregnated with silver nitrate (2%). Morphometric characteristics were determined and schematic drawings of the denticles were made using photomicrographs produced from the slides. Seven species of trichodinid ectoparasites (Protozoa: Ciliophora: Trichodinidae) were found parasitizing the gills: four of the genus Trichodina Ehrenberg, 1838; one of Tripartiella Lom, 1959; one of Paratrichodina Lom, 1963; and one of Trichodinella Ṧrámek-Huṧek, 1953. On the body surface, three specimens of the genus Trichodina were identified. This study presents new geographical records of trichodinids in Brazil, thus confirming that Trichodina centrostrigeata, Trichodina compacta, Trichodina heterodentata, Paratrichodina africana and Tripartiella orthodens are widely distributed worldwide. Additionally, the first record of the genus Trichodinella in Brazil is presented.

Resumo O parasitismo intenso por tricodinídeos está frequentemente relacionado à doença grave em fazendas de peixes. Neste estudo, espécies de tricodinídeos das brânquias e da pele de tilápias do Nilo (Oreochromis niloticus) cultivadas na região centro-oeste do Brasil (estado de Goiás) foram caracterizadas morfologicamente. As lâminas secas foram preparadas a partir dos parasitas e impregnadas com nitrato de prata (2%). As características morfométricas foram determinadas e desenhos esquemáticos dos dentículos foram confeccionados com fotomicrografias produzidas a partir das lâminas. Sete espécies de ectoparasitos tricodinídeos (Protozoa: Ciliophora: Trichodinidae) foram encontradas parasitando as brânquias: quatro do gênero Trichodina Ehrenberg, 1838; um de Tripartiella Lom, 1959; um de Paratrichodina Lom, 1963; e um de Trichodinella Ṧrámek-Huṧek, 1953. Na superfície do corpo, três espécimes do gênero Trichodina foram identificados. Este estudo apresenta novos registros geográficos de tricodinídeos no Brasil, confirmando que Trichodina centrostrigeata, Trichodina compacta, Trichodina heterodentata, Paratrichodina africana e Tripartiella orthodens estão amplamente distribuídas mundialmente. Adicionalmente, é apresentado o primeiro registro do gênero Trichodinella no Brasil.

Detection and Quantification of Two Parasitic Ciliates Boveria labialis and Boveria subcylindrica (Ciliophora: Scuticociliatia) by Fluorescence in situ Hybridization.

The thigmotrich scuticociliates Boveria labialis and Boveria subcylindrica are obligate parasites that may cause high mortality in cultured sea cucumbers and bivalves. Morphological methods can identify these organisms in active state, but are unable to discern them in resting stages. In aquaculture practice, these parasitic ciliates are hard to eradicate when massive infection occurs in sea cucumbers. Thus, early detection and precaution are crucial for the control of these pathogens. Under such circumstances, fluorescence in situ hybridization (FISH) will serve as a fast way to detect and monitor the occurrence of these parasites. We designed two SSU-rDNA targeted oligonucleotide probes labeled with fluorochromes, and optimized the FISH protocols for the detection of B. labialis and B. subcylindrica from the host sea cucumber Apostichopus japonicus and the bivalve Atrina pectinata, respectively. The assays resulted in a clear differentiation of the two similar species by strong fluorescence signals from the oligonucleotide probes. Moreover, we successfully used the FISH protocol to detect the cysts of B. labialis and variation in abundance of active parasites to evaluate the efficacy of chemical treatments. This is the first report and detection of the cysts of B. labialis from the host sea cucumber A. japonicus.

The Green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with Its Endosymbiotic Algae (Micractinium sp.), Living in Traps of a Carnivorous Aquatic Plant.

The genus Tetrahymena (Ciliophora, Oligohymenophorea) probably represents the best studied ciliate genus. At present, more than forty species have been described. All are colorless, i.e. they do not harbor symbiotic algae, and as aerobes they need at least microaerobic habitats. Here, we present the morphological and molecular description of the first green representative, Tetrahymena utriculariae n. sp., living in symbiosis with endosymbiotic algae identified as Micractinium sp. (Chlorophyta). The full life cycle of the ciliate species is documented, including trophonts and theronts, conjugating cells, resting cysts and dividers. This species has been discovered in an exotic habitat, namely in traps of the carnivorous aquatic plant Utricularia reflexa (originating from Okavango Delta, Botswana). Green ciliates live as commensals of the plant in this anoxic habitat. Ciliates are bacterivorous, however, symbiosis with algae is needed to satisfy cell metabolism but also to gain oxygen from symbionts. When ciliates are cultivated outside their natural habitat under aerobic conditions and fed with saturating bacterial food, they gradually become aposymbiotic. Based on phylogenetic analyses of 18S rRNA and mitochondrial cox1 genes T. utriculariae forms a sister group to Tetrahymena thermophila.

A new species of Tripartiella (Ciliophora: Trichodinidae) from Aequidens tetramerus (Perciformes: Cichlidae) in north Brazil / Uma nova espécie de Tripartiella (Ciliophora: Trichodinidae) em Aequidens tetramerus no norte do Brasil

Abstract A new species of Tripartiella is described from the gills of the wild saddle cichlid Aequidens tetramerus in north Brazil. Wet smears of skin and gills of examined fish were air-dried at room temperature and impregnated with Klein’s dry silver method for examination of the adhesive disc’s structures and denticles. Total prevalence of parasitism was 65%. This ciliate is characterized as a small-sized trichodinid, body diameter 37.03 ± 4.9 μm, adhesive disc 30.50 ± 2.71 μm, denticulate ring 13.28 ± 0.8 μm and 24 ± 2.0 denticles. Taxonomic and morphometric data for the new species are discussed.

Resumo Um nova espécie de Tripartiella encontrada nas brânquias de Aequidens tetramerus da região Norte do Brasil é descrita. Esfregaços de pele e brânquias de peixes examinados foram secos à temperatura ambiente e impregnados pelo método de Klein para observação das estruturas do disco adesivo e dentículos. A prevalência do parasitismo foi de 65%. Este ciliado é caracterizado como pequeno trichodinídeo, com corpo medindo 37,03 ± 4,9 μm de diâmetro, disco adesivo com 30,50 ± 2,71 μm, anel denticulado com 13,28 ± 0,8 μm e 24 ± 2,0 dentículos. Dados taxonômicos e morfométricos para a nova espécie são discutidos.

Trichodinosis associated with pathology of the reproductive tract in waterfowl.

Trichodinid ciliophorans are opportunistic parasites of many species of fish, amphibians, and molluscs, but yet never reported in association with lesions in birds. Postmortem and histopathological evaluation of a commercial adult Toulouse gander and female goose, and a wild Mallard drake revealed the presence of severe pathological parasitic colonization of their reproductive tracts. Histopathological findings included moderate to severe granulocytic inflammation, acanthosis, accentuation of the rete pegs, and proliferative hyperplastic squamous metaplasia of the mucosa of the ejaculatory ducts and groove, sulcus spermaticus, glandular part of the phallus (cavum penis), and oviduct in association with large numbers of ciliated protozoa anchored to the tissues or free in the lumen. These protozoa had characteristic morphological features analogous to the family of Trichodinidae. The source of this parasitism could not be determined. To our knowledge, this is the first report of trichodinosis associated with pathology in birds.

First record of an epibiont protozoan Epistylis sp. (Ciliophora, Peritrichia) attached to Ergasilus chelangulatus (Ergasilidae) in Brazil / Primeiro registro do protozoário epibionte Epistylis sp. (Ciliophora, Peritrichia) aderido à Ergasilus chelangulatus (Ergasilidae) no Brasil

In the present paper, we described the first record of an epibiont protozoan Epistylis sp. Ehrenberg, 1830 (Ciliophora, Peritrichia) attached to Ergasilus chelangulatus Thatcher and Brasil-Sato, 2008, parasite of Pimelodus maculatus Lacépède, 1803 in Brazil, with electron microscope observations. Fish were collected in Veados River, state of São Paulo and the crustacean Ergasilus chelangulatus being registered for the first time in this river, expanding its geographical distribution in Brazil.

No presente trabalho nós descrevemos o primeiro registro de um protozoário epibionte Epistylis sp. Ehrenberg, 1830 (Ciliophora, Peritrichia) aderido à Ergasilus chelangulatus Thatcher e Brasil-Sato, 2008, parasito de Pimelodus maculatus Lacépède, 1803 no Brasil, com observações de microscopia eletrônica. Os peixes foram coletados no Rio dos Veados, estado de São Paulo e o crustáceo Ergasilus chelangulatus está sendo registrado pela primeira vez neste rio, ampliando sua distribuição geográfica no Brasil.

Spatial genetic variation, phylogeography and barcoding of the peritrichous ciliate Carchesium polypinum.

Most recent studies of geographic distribution of microbial eukaryotes have focused on marine rather than freshwater protists. Here, we used the freshwater peritrich ciliate Carchesium polypinum to quantify the degree of genetic diversity of four closely related and previously described lineages and to determine whether patterns of genetic differentiation showed geographic partitioning. Using an expanded dataset of 100 isolates and employing the mitochondrial marker cytochrome oxidase c subunit I (cox-1), we enriched the 6 previously identified clades of Carchesium polypinum. We found a large degree of geographic overlap among the different clades (e.g. to the level of range of sampling), but also a spatially restricted clade (e.g. to the level of one river basin). Furthermore, we present evidence of a clear geographic separation in one of the lineages with Canadian and North Carolinian isolates grouping in two distinct clusters.

Trichodina nobilis Chen, 1963 and Trichodina reticulata Hirschmann et Partsch, 1955 from ornamental freshwater fishes in Brazil / Trichodina nobilis Chen, 1963 e Trichodina reticulata Hirschmann et Partsch, 1955 de peixes ornamentais de água doce no Brasil

In the present work Trichodina reticulata and T. nobilis (Ciliophora: Trichodinidae) are morphologically characterised from ornamental freshwater fish culture in the State of Santa Catarina, Brazil. The prevalence of infection and a list of comparative measurements are discussed. We examined "southern platyfish" Xiphophorus maculatus (n = 35), "goldfish" Carassius auratus (n = 31), "guppy" Poecilia reticulata (n = 20), "sailfin molly" Poecilia latipinna (n = 6), "beta" Betta splendens (n = 2) and "spotted headstander" Chilodus punctatus (n = 1). After being anesthetised in a benzocaine solution, fishes were examined for parasitological evaluation. A total of 51.57% fishes were parasitised by Trichodina spp. Carassius auratus was the most parasitised species, followed by X. maculatus and P. reticulata. Beta splendens, C. punctatus and P. latipinna were not parasitised by any trichodinid species. Two species of Trichodina were collected from the skin of fish: T. nobilis was found in C. auratus, P. reticulata and X. maculatus and T. reticulata was only observed in C. auratus. The importance of adequate handling in ornamental fish culture are also discussed.

No presente trabalho Trichodina reticulata e T. nobilis (Ciliophora: Trichodinidae) de peixes ornamentais de água doce cultivados no estado de Santa Catarina, Brasil são caracterizadas morfologicamente. A prevalência de infecção e uma lista comparative de medidas são discutidas. Foram examinados "platis" Xiphophorus maculatus (n = 35), "kinguios" Carassius auratus (n = 31), "guppys" Poecilia reticulata (n = 20), "molinésias" Poecilia latipinna (n = 6), "betas" Betta splendens (n = 2) e "espada" Chilodus punctatus (n = 1). Após a anestesia com solução de benzocaína, os peixes foram submetidos à avaliação parasitológca. Um total de 51,57% peixes estavam parasitados por Trichodina spp. Carassius auratus foi a espécie mais parasitada, seguida por X. maculatus e P. reticulata. Beta splendens, C. punctatus e P. latipinna não estavam parasitados por tricodinídeos. Duas species de Trichodina foram coletadas da superfície corporal dos peixes: T. nobilis foi encontrada em C. auratus, P. reticulata e X. maculatus e T. reticulata foi observada apenas em C. auratus. A importância do manejo adequado em cultivos de peixes ornamentais também foi discutida.

Insights into the phylogenetic and taxonomy of philasterid ciliates (Protozoa, Ciliophora, Scuticociliatia) based on analyses of multiple molecular markers.

Scuticociliates are a rich assemblage of species with mostly unresolved phylogenetic relationships, especially in the order Philasterida. In the present work, 48 new sequences for three linked genes are characterized and phylogenetic trees are constructed to assess the inter- and intra-generic relationships of philasterids. Results reveal the following: (1) the combined three-gene tree provides more resolution in nodes than in the SSU-rDNA topologies; (2) the family Orchitophryidae is non-monophyletic as it is split into two parts and Paranophrys magna, Metanophrys sp. and Metanophrys sinensis are designated incertae sedis at the familial level; (3) Uronematidae is non-monophyletic and Homalogastra setosa is designated incertae sedis; (4) Parauronematidae becomes a junior synonym of Uronematidae and the clade containing A. haemophila, Miamiensis avidus, and Glauconema trihymene might stand for a new family; (5) Parauronema being a junior synonym of Uronema is supported and P. longum should be removed from the genus Parauronema; (6) Uronema is not monophyletic and molecular analyses reveal that Uronema sp. QD shares a more recent common ancestor with Uronemella species than with other Uronema species; (7) Metanophrys is polyphyletic; (8) multiple samples of two highly controversial species, viz., Mesanophrys pugettensis and M. chesapeakensis have identical ITS1-5.8S-ITS2 region sequence and we propose they should be synonymous with M. carcini, and (9) there may be cryptic species in M. carcini and M. avidus.

A new interpretation of stomatogenesis in a peritrich ciliate: using Campanella umbellaria as a model system.

The process of stomatogenesis in peritrich ciliates is still incompletely understood. Previous studies on the stomatogenesis of four species of peritrichs, Telotrochidium sp., Carchesium polypinum, Opercularia coarctata, and Astylozoon pyriforme conflict with one another in some cases and omit details of events in others. We described the entire process of stomatogenesis in the peritrich ciliate Campanella umbellaria (C. umbellaria) using an improved method of staining with protargol. Our results disagree with some previous studies with regard to the formation of some rudimentary structures, reorganization of the parental haplokinety, formation of new germinal rows, and separation of daughter oral complexes. The pattern of stomatogenesis characteristic of peritrichs is compared to the stomatogenetic patterns of three other oligohymenophorean subclasses and a hypothesis about the evolution of stomatogenesis in the class Oligohymenophorea is offered. Details of stomatogenesis need to be described and verified in a greater variety of peritrichs to clarify possible differences between taxa and make it possible to relate stomatogenesis to evolution within the subclass Peritrichia. Ultrastructural studies are the next step in description of morphogenetic processes in peritrichs, and characteristics of C. umbellaria make it a useful model for this work.

Two novel marine Frontonia species, Frontonia mengi spec. nov. and Frontonia magna spec. nov. (Protozoa; Ciliophora), with notes on their phylogeny based on small-subunit rRNA gene sequence data.

The morphology and infraciliature of two novel marine ciliates, Frontonia mengi spec. nov. and Frontonia magna spec. nov., isolated from coastal waters in northern and southern China, respectively, were investigated using living observation and silver impregnation methods. Frontonia mengi spec. nov. is characterized by its slender body shape, with a length-to-width ratio of about 5 : 1, about 52 somatic kineties and the structure of its buccal apparatus. Frontonia magna spec. nov. can be recognized by the combination of huge body size, about 200 somatic kineties, five or six vestibular kineties and four-rowed peniculi 1-3. Phylogenetic trees based on small-subunit rRNA gene sequences were constructed by means of Bayesian inference and maximum-parsimony. Results showed that F. mengi and F. magna are sister to each other within the 'core' clade of Frontonia that also includes Frontonia lynni and Frontonia tchibisovae and that the genus Frontonia may be polyphyletic, because one species, Frontonia didieri, always groups with Paramecium and Apofrontonia.

First isolation of Pseudocohnilembus persalinus (Ciliophora: Scuticociliatida) from freshwater-reared rainbow trout, Oncorhynchus mykiss.

Ciliated protists were isolated from the ovarian fluid of apparently healthy adult rainbow trout (Oncorhynchus mykiss) maintained in freshwater. The organism was identified as Pseudocohnilembus persalinus based on morphometric and morphological analysis of silver-stained specimens obtained from culture and on analysis of ribosomal RNA gene sequences. The cytochrome c oxidase subunit 1 gene sequence of this organism also was characterized. This ciliate has been reported previously as free living only in saline environments and as an endosymbiont in a marine teleost, the olive flounder (Paralichthys olivaceus). A cyst-like stage may have facilitated the novel occurrence of this organism as an endosymbiont in rainbow trout.

Evidence for cryptic speciation in Carchesium polypinum Linnaeus, 1758 (Ciliophora: Peritrichia) inferred from mitochondrial, nuclear, and morphological markers.

Protist diversity is currently a much debated issue in eukaryotic microbiology. Recent evidence suggests that morphological and genetic diversity might be decoupled in some groups of protists, including ciliates, and that these organisms might be much more diverse than their morphology implies. We sought to assess the genetic and morphological diversity of Carchesium polypinum, a widely distributed peritrich ciliate. The mitochondrial marker cytochrome c oxidase subunit I and the nuclear small subunit ribosomal RNA were used to examine genetic diversity. For the morphological assessment, live microscopy and Protargol staining were used. The mitochondrial marker revealed six robust, deeply diverging, and strongly supported clades, while the nuclear gene was congruent for three of these clades. There were no major differences among individuals from the different clades in any of the morphological features examined. Thus, the underlying genetic diversity in C. polypinum is greater than what its morphology suggests, indicating that morphology and genetics are not congruent in this organism. Furthermore, because the clades identified by the mitochondrial marker are so genetically diverse and are confirmed by a conserved nuclear marker in at least three cases, we propose that C. polypinum be designated as a "cryptic species complex." Our results provide another example where species diversity can be underestimated in microbial eukaryotes when using only morphological criteria to estimate species richness.

Description of Paratetrahymena parawassi n. sp. using morphological and molecular evidence and a phylogenetic analysis of Paratetrahymena and other taxonomically ambiguous genera in the order Loxocephalida (Ciliophora, Oligohymenophorea).

The marine scuticociliate Paratetrahymena parawassi n. sp. is described on the basis of morphology, especially infraciliature, and the sequence of its small subunit (SSU) rRNA gene to become the second known member of its genus. Paratetrahymena and other ciliates in the order Loxocephalida possess a mixture of morphological and morphogenetic features characteristic of the subclasses Hymenostomatia and Scuticociliatia. Accordingly, we used SSU rRNA sequences to analyze the phylogeny of Paratetrahymena and three other loxocephalid genera. Paratetrahymena and Cardiostomatella vermiformis formed a moderately well-supported clade that diverged at a deep level from all other scuticociliates, supporting separation of loxocephalids from other scuticociliates as a suprafamilial taxon. Sathrophilus holtae was a sister taxon to Paratetrahymena and Cardiostomatella in a poorly supported, unresolved relationship; nevertheless, association of all three genera into a single clade was supported by an approximately unbiased (AU) test. Any association of these genera singly or as a group with the Hymenostomatia was rejected decisively by AU tests and by a complete absence in the loxocephalids of the unique nucleotide identities that distinguish hymenostomes. Therefore, the morphological and morphogenetic similarities of loxocephalids to hymenostomes may be plesiomorphies, and the conflicting mix of scuticociliate and hymenostome characteristics seen in loxocephalids may result from differing rates of character evolution. Dexiotrichides pangi and Urocentrum, which is currently classified as a peniculid, formed a small clade that associated with hymenostomes and peritrichs. Monophyly of the Loxocephalida with Dexiotrichides and/or Urocentrum included was not rejected by AU; however, inclusion of Urocentrum in the Peniculia was rejected by AU tests. A hypothesis is offered to explain the lack of resolution of loxocephalid ciliates and Urocentrum in phylogenetic trees, namely that their phylogenetic positions are influenced by a combination of heterogeneous data and long-branch attraction caused by poor representation of taxa in analyses. The well-known genus Cyclidium, a member of the order Pleuronematida, was revealed to be polyphyletic as a byproduct of our analyses of loxocephalids. In particular, Cyclidium porcatum appears to fall outside the clade containing typical members of the subclass Scuticociliatia and thus invites investigation as a possible member of the order Loxocephalida.

First record of Trichodina heterodentata (Ciliophora: Trichodinidae) from channel catfish, Ictalurus punctatus cultivated in Brazil / Primeiro registro de Trichodina heterodentata (Ciliophora: Trichodinidae) em bagre-do-canal, Ictalurus punctatus cultivado no Brasil

This study characterises morphologically Trichodina heterodentata Duncan, 1977 from channel catfish, Ictalurus punctatus (Rafinesque, 1818) in the State of Santa Catarina, Brazil. Body and gill smears were air-dried at room temperature, impregnated with silver nitrate and/or stained with Giemsa. Ten characteristics were selected to compare the present material with other morphological characterisations of T. heterodentata. Prevalence rate was 100 percent, mean intensity 89,333.70 (3,125 to 299,100 parasites per host). Trichodina heterodentata was considered medium-sized trichodinid with mean body diameter 59.4 ± 8.5 μm, denticulate ring 38.5 ± 4.5 μm, adhesive disc 60.2 ± 6.7 μm diameter and 24.4 ± 1.6 denticles. In relation to previous reports of T. heterodentata this material resembles in 90 percent of the analysed characters. This work confirms the biometrical variation that exists in the different populations of T. heterodentata. A list of hosts and comparative measurements of T. heterodentata are presented and the channel catfish is considered a new host.

Este estudo caracteriza morfologicamente Trichodina heterodentata Duncan, 1977 em bagre-do-canal, Ictalurus punctatus (Rafinesque, 1818) no Estado de Santa Catarina, Brasil. Esfregaços do corpo e brânquias foram secados à temperatura ambiente, impregnados com nitrato de Prata e/ou corados com Giemsa. Dez características foram selecionadas para comparar o presente material com as diferentes caracterizações morfológicas de T. heterodentata. A taxa de prevalência foi de 100 por cento, a intensidade média foi de 89.333.75 (3.125 a 299.100 parasitos por hospedeiro). Trichodina heterodentata foi considerado um tricodinídeo de tamanho médio com a média do diâmetro do corpo de 59,4 ± 8.5 μm, anel denticulado 38,5 ± 4,5 μm, disco adesivo 60,2 ± 6,7 μm de diâmetro e 24,4 ± 1,6 dentículos. Em relação a registros prévios de T. heterodentata, 90 por cento das características foram semelhantes. Este trabalho confirma a variação biométrica que existe em diferentes populações de T. heterodentata. Uma lista de hospedeiros e medidas comparativas de T. heterodentata são apresentadas e o bagre-do-canal considerado um novo hospedeiro.

Diverse modes of reproduction in the marine free-living ciliate Glauconema trihymene.

BACKGROUND: Most free-living ciliates reproduce by equal fission or budding during vegetative growth. In certain ciliates, reproduction occurs inside the cyst wall, viz. reproductive cysts, but more complex reproductive strategies have generally been thought to be confined to parasitic or symbiotic species, e.g. Radiophrya spp. RESULTS: In addition to equal fission, asymmetric binary division and reproductive cysts were discovered in the free-living bacterivorous scuticociliate Glauconema trihymene Thompson, 1966. Asymmetric division is an innate physiological state that can be induced by sufficient food, and the higher the food concentration, the longer the asymmetric division persists. During asymmetric division, nuclear and somatic structures divide with transiently arrested cytokinesis and variable positioning of macronuclei. Phylogenetic analysis, based on the small subunit of ribosomal DNA (SSU rDNA) sequences, showed that the G. trihymene isolate studied here nests with typical scuticociliates and is paraphyletic to both the symbiotic apostome and astome ciliates, some of which also produce progeny by asymmetric division. CONCLUSIONS: The asymmetric division in G. trihymene has no precedent among undisturbed free-living ciliates. The coexistence of multiple modes of reproduction may represent a previously undescribed reproductive strategy for ciliates living on food patches in coastal waters. This may also be indicative of similar reproductive strategies among other polyphenic ciliates, which have not been intensively studied. Asymmetric division provides a special opportunity for studying ciliates' phenotypic plasticity and may also illuminate the origins of multicellularity.