Checklist of species in the genus Epistylis (Ciliophora, Peritrichia): the first step for a taxonomic revision.

The subclass Peritrichia includes sessile ciliates that attach to aquatic non-living or living substrates. In the case of the latter, they live in a relationship called epibiosis. The genus Epistylis Ehrenberg,1830 is the second-most speciose genus within Sessilida, being characterized by its colonial lifestyle and having a non-contractile stalk. Species of Epistylis have been described from a wide range of aquatic habitats worldwide. The main goal of the present study is to provide a global checklist of the valid species of Epistylis, which may serve as a first step towards a taxonomic review of the genus.

Cross-infectivity of Vorticella sp. across genera of mosquitoes for development of biological mosquito control strategies.

Protists in general comprise about one-third of the parasitic species infecting arthropod vectors, the role of free-living and epibiotic ciliates on mosquitoes have been insufficiently studied either due to their low pathogenicity or facultative parasites. Studies have shown that exposure of Paramecium ciliate protists, like Vorticella species, to first instar Culex nigripalpus Theobald, larvae delayed larval development and reduced biomass of emerged adults due to competition for food sources like bacteria and other microbes essential to mosquito growth and survival. Thus, we report on the capacity of a Vorticella sp. protist's ability to cross-infect host species and parasitize multiple mosquito larvae. The unique adapted behavior with the ability to remain on the exuviae in tree hole habitats provide a novel delivery system to develop products for target species-specific mosquitocides, larvicides, or viricides to be applied and sustained in aquatic systems.

Systematic review of the genera Rhabdostyla Kent 1880 and Orborhabdostyla Foissner et al. 2010 (Ciliophora, Peritrichia, Epistylididae).

The genus Rhabdostyla is one of the oldest of the family Epistylididae, it was described over 120 years ago and has more than 40 species considered valid. This group went through several systematic changes throughout its existence and due to the lack of taxonomic information, said to be essential, for most species that compose it, some of these changes are still questioned. In order to better understand and validate the species and relationships identified for this genus, the present work makes a brief review for the genus Rhabdostyla and its related genera, Opisthostyla and Orborhabdostyla. A 18S-rDNA phylogenetic analysis was also performed to understand the relationship between these groups. As a result of this review, 45 diagnoses were compiled and reorganized for the current model, accompanied by new graphical representations for the species considered valid for the genus Rhabdostyla and its associates. The major changes that the genus underwent, such as synonymy and separation to a new genus, were discussed in light of new phylogenetic information, but despite this, other information is still needed for a better validation of these changes.

Paramecium (Oligohymenophorea, Ciliophora) diversity in Thailand sheds light on the genus biogeography and reveals new phylogenetic lineages.

Paramecium (Ciliophora, Oligohymenophorea) is a good model to study ciliate biogeography. Extensive sampling mainly in northern hemisphere has led to 16 valid morphological species description thus far. However, a majority of hard-to-reach regions, including South East Asia, are underinvestigated. Our study combined traditional morphological and molecular approaches to reveal the biodiversity of Paramecium in Thailand from more than 110 samples collected in 10 provinces. Representatives of seven morphological species were identified from our collection, including the rare species, such as P. gigas and P. jenningsi. Additionally, we detected five different sibling species of the P. aurelia complex, described a new cryptic species P. hiwatashii n. sp. phylogenetically related to P. caudatum, and discovered a potentially new genetic species of the P. bursaria species complex. We also documented a variety of bacterial cytoplasmic symbionts from at least nine monoclonal cultures of Paramecium.

Deciphering phylogenetic relationships of and delimiting species boundaries within the controversial ciliate genus Conchophthirus using an integrative morpho-evo approach.

The phylum Ciliophora (ciliates) comprises about 2600 symbiotic and over 5500 free-living species. The inclusion of symbiotic ciliates in phylogenetic analyses often challenges traditional classification frameworks due to their morphological adaptions to the symbiotic lifestyle. Conchophthirus is such a controversial obligate endocommensal genus whose affinities to other symbiotic and free-living scuticociliates are still poorly understood. Using uni- and multivariate morphometrics as well as 2D-based molecular and phylogenetic analyses, we attempted to test for the monophyly of Conchophthirus, study the boundaries of Conchophthirus species isolated from various bivalves at mesoscale, and reveal the phylogenetic relationships of Conchophthirus to other scuticociliates. Multidimensional analyses of morphometric and cell geometric data generated the same homogenous clusters, as did phylogenetic analyses based on 144 new sequences of two mitochondrial and five nuclear molecular markers. Conchophthirus is not closely related to 'core' scuticociliates represented by the orders Pleuronematida and Philasterida, as assumed in the past using morphological data. Nuclear and mitochondrial markers consistently showed the free-living Dexiotricha and the mouthless endosymbiotic Haptophrya to be the nearest relatives of Conchophthirus. These three highly morphologically and ecologically dissimilar genera represent an orphan clade from the early radiation of scuticociliates in molecular phylogenies.

Host-parasite interactions: a study on the pathogenicity of different Mesanophrys sp. densities and hemocytes-mediated parasitic resistance of swimming crabs (Portunus trituberculatus).

Mesanophrys sp. is a parasitic ciliate that invades and destroys the hemocytes of the swimming crab (Portunus trituberculatus). In the present study, we employed an in vitro model to elucidate how Mesanophrys sp. destroys crab hemocytes. We also evaluated the relationship between the parasite's density, the destruction rate of the hemocytes, and the rapid proliferation pattern of parasites in host crabs. We found that the survival rate and cell integrity of crab hemocytes decreased with an increase in Mesanophrys sp. density, depicting a negative correlation between hemocyte viability and parasite density. Further analyses revealed that crab hemocytes could resist destruction by a low density (10 ind/mL) of Mesanophrys sp. for a long time (60 h). Mesanophrys sp. and its culture medium (containing the ciliate secretions) destroy the host hemocytes. The natural population growth rate of Mesanophrys sp. decreased with an increase in the parasite density, but the Mesanophrys sp. density did not affect the generation time of the parasites. In summary, Mesanophrys sp. can destroy crab hemocytes, and the degree of destruction is directly proportional to the parasite density. The resistance of crab hemocytes to Mesanophrys sp. decreased gradually with an increase in the parasite density.

Prevalence of the scuticociliate Orchitophrya stellarum in seastars from the Pacific and Atlantic oceans.

As part of a study to investigate the use of the scuticociliate Orchitophrya stellarum as a biological control for the invasive seastar Asterias amurensis in Australia, we collected prevalence data for O. stellarum from 3 seastar species (A. amurensis, A. rubens, Pisaster ochraceus) between 1996 and 1999 from the Pacific (Australia, Japan, Korea, Canada) and Atlantic (France, Netherlands, Canada) oceans. In the Pacific Ocean, for the first time, we found O. stellarum in male A. amurensis in Korea and female A. amurensis in Japan. The parasite was not detected in the invasive A. amurensis from Australia. There was no significant difference between size of infected and uninfected male seastars, nor a correlation between biased sex ratio and parasite prevalence in populations in the Pacific or Atlantic oceans. Therefore, unlike other studies, we found size and sex ratio in seastar populations in the field are unreliable indicators of parasite impacts. Regular monitoring of infected seastar populations in the field would be useful to better understand how sex ratio varies with parasite prevalence. We recommend laboratory studies under controlled conditions to determine the effect of O. stellarum on seastar populations.

Formulation of chitosan microsphere-based oral vaccine against the scuticociliate parasite Miamiensis avidus: Evaluation of its protective immune potency in olive flounder (Paralichthys olivaceus).

Miamiensis avidus is a parasitic pathogen that causes scuticociliatosis, a severe and often lethal marine infection that affects marine fishes worldwide, including olive flounder (Paralichthys olivaceus) in Korea. This parasite infects all size groups of flounder year-round, causing recurring mortalities and huge economic losses to the Korean flounder industry each year. However, few efforts have been made to implement effective remedial measures to control this parasite. Therefore, our study sought to develop a chitosan microsphere (MS)-encapsulated inactivated vaccine (IMa + chitosan) for oral delivery (adsorbed in feed) to flounder fingerlings and assess its protective efficacy at different modalities via three in vivo experimental trials. Immunisation trial-1 was conducted to determine the effective concentration of chitosan. Our findings indicated that an IMa + chitosan 0.05 % vaccine formulation was safe and effective in providing moderate protection [46.67%-53.3 % relative percent survival (RPS)] against M. avidus intraperitoneal (IP) injection challenge at two weeks post-vaccination (wpv) compared to the IMa + chitosan 0.01 % and IMa + chitosan 0.005 % vaccines (0%-13.3 % RPS) irrespective of the antigen doses. In trial-2, the IMa + chitosan 0.05 % vaccine elicited similar protective immunity (30.8%-57.1 % RPS) in olive flounder against M. avidus at varying antigen doses (high: 2.38 × 106 cells/fish; low: 1.5 × 105 cells/fish), immunisation periods (2 and 5 wpv), and challenge modes (IP injection and immersion). Furthermore, experimental trial-3 validated the use of chitosan MS as an IMa antigen carrier to improve survivability (41.7 % RPS) in the host by significantly (p < 0.05) upregulating specific anti-M. avidus antibody titres in the fish sera and mucus of the group immunised with IMa-containing chitosan MS. In contrast, non-specific immunomodulatory effects (16.7 % RPS and enhanced mucosal antibody titres) were observed in the group treated with chitosan MS without IMa. Therefore, our findings suggested that oral administration of chitosan MS (0.05 %)-encapsulated IMa vaccine is a promising immunisation strategy against M. avidus that can protect the IMa antigen from digestive degradation, facilitates its targeted delivery to the host immune organs, and helps in orchestrating protective immune induction in olive flounder, thus controlling parasite infection.

Life history of Apocarchesium arndti Norf & Foissner, 2010 (Ciliophora, Peritrichia) including recognition of a novel type of zooid.

Apocarchesium rosettum and A. arndti were originally discovered in Japan (Lake Biwa) and Germany (River Rhine), respectively. We report the first record of A. arndti in the Danube and provide a detailed description of its colony development. Our findings support the theory of moderate endemicity and reveal a new, smaller zooid type in A. arndti. This zooid remains attached to the colony, connected to the stalk myoneme but lacks an aboral ciliary wreath. Unlike microzooids, it is incapable of leaving the colony. It exhibits a less spherical shape and arises from the fourth division of the colony-founder cell. Although its specific function is unknown, it is hypothesized to support the stalk dish. Our results have significant implications for understanding the systematics of vorticellids, suggesting their ancestral nature as colonial organisms characterized by a helically contracting stalk myoneme. Furthermore, the exclusive retention of the stalk myoneme by the parental cell after binary fission may serve as a synapomorphy for the Vorticellidae. We provide a descriptive analysis of the ecological environment and microhabitat of A. arndti in the Danube, revealing its preference for well-developed, detritus-rich biofilms during summer, absence in late winter and spring, emergence during peak summer, and subsequent decline until mid-winter.

Anaerocyclidiidae fam. nov. (Oligohymenophorea, Scuticociliatia): A newly recognized major lineage of anaerobic ciliates hosting prokaryotic symbionts.

The research on anaerobic ciliates, to date, has mainly been focused on representatives of obligately anaerobic classes such as Armophorea or Plagiopylea. In this study, we focus on the anaerobic representatives of the subclass Scuticociliatia, members of the class Oligohymenophorea, which is mainly composed of aerobic ciliates. Until now, only a single anaerobic species, Cyclidium porcatum (here transferred to the genus Anaerocyclidium gen. nov.), has been described both molecularly and morphologically. Our broad sampling of anoxic sediments together with cultivation and single cell sequencing approaches have shown that scuticociliates are common and diversified in anoxic environments. Our results show that anaerobic scuticociliates represent a distinctive evolutionary lineage not closely related to the family Cyclidiidae (order Pleuronematida), as previously suggested. However, the phylogenetic position of the newly recognized lineage within the subclass Scuticociliatia remains unresolved. Based on molecular and morphological data, we establish the family Anaerocyclidiidae fam. nov. to accommodate members of this clade. We further provide detailed morphological descriptions and 18S rRNA gene sequences for six new Anaerocyclidium species and significantly broaden the described diversity of anaerobic scuticociliates.

Comparative genomics provides insights into the phylogeny and environmental adaptations of Peritrichia (Protista, Ciliophora) - A potential resource for environmental pollution control and bioremediation.

Peritrichs are one of the largest groups within the class Oligohymenophorea. They have a worldwide distribution and a high degree of species diversity. Using the single-cell genome sequencing technique, we obtained the genomes of five sessilid peritrichs. Combining both genomic and transcriptomic data of other publicly available oligohymenophorean ciliates (including the genomes of three sessilid peritrichs from our team's previous study), we conducted a comparative genomics study. Our phylogenomic analyses using both maximum likelihood and Bayesian inference methods recovered the subclass Peritrichia and each of its two orders (Sessilida and Mobilida) as being monophyletic. The non-monophyly of two families (Vorticellidae and Zoothamniidae) was also well supported in both trees. Molecular clock analysis showed that the origin of the subclass Peritrichia was estimated to be during the late Proterozoic. We also analyzed the stop codon usage of 44 oligohymenophoreans. The results showed that most of these species used TGA as the biased stop codon and reassigned the other two stop codons (TAA and TAG) to code amino acids. In addition, we found that the presence of a typical peritrich lorica is a plesiomorphic character of the family Vaginicolidae. Through GO enrichment analysis for group-specific orthogroups of Vaginicolidae, we successfully identified the biological process and molecular function GO terms that were linked with the typical peritrich lorica, including three glycosaminoglycan-related and two chitin-related GO terms. Finally, our enrichment analyses of significantly expanded gene families in Peritrichia found that sessilids were more tolerant to environmental stress (mainly organic matter) than mobilids, suggesting that peritrich lineages (especially sessilids) may have the potential for application in environmental pollution control and bioremediation. Together, the results presented in this study will facilitate wider genome-scale phylogenetic analyses of Peritrichia and deepen the understanding of their unique advantages for environmental pollution control bioremediation.

The photic-aphotic divide is a strong ecological and evolutionary force determining the distribution of ciliates (Alveolata, Ciliophora) in the ocean.

The bulk of knowledge on marine ciliates is from shallow and/or sunlit waters. We studied ciliate diversity and distribution across epi- and mesopelagic oceanic waters, using DNA metabarcoding and phylogeny-based metrics. We analyzed sequences of the 18S rRNA gene (V4 region) from 369 samples collected at 12 depths (0-1000 m) at the Bermuda Atlantic Time-series Study site of the Sargasso Sea (North Atlantic) monthly for 3 years. The comprehensive depth and temporal resolutions analyzed led to three main findings. First, there was a gradual but significant decrease in alpha-diversity (based on Faith's phylogenetic diversity index) from surface to 1000-m waters. Second, multivariate analyses of beta-diversity (based on UniFrac distances) indicate that ciliate assemblages change significantly from photic to aphotic waters, with a switch from Oligotrichea to Oligohymenophorea prevalence. Third, phylogenetic placement of sequence variants and clade-level correlations (EPA-ng and GAPPA algorithms) show Oligotrichea, Litostomatea, Prostomatea, and Phyllopharyngea as anti-correlated with depth, while Oligohymenophorea (especially Apostomatia) have a direct relationship with depth. Two enigmatic environmental clades include either prevalent variants widely distributed in aphotic layers (the Oligohymenophorea OLIGO5) or subclades differentially distributed in photic versus aphotic waters (the Discotrichidae NASSO1). These results settle contradictory relationships between ciliate alpha-diversity and depth reported before, suggest functional changes in ciliate assemblages from photic to aphotic waters (with the prevalence of algivory and mixotrophy vs. omnivory and parasitism, respectively), and indicate that contemporary taxon distributions in the vertical profile have been strongly influenced by evolutionary processes. Integration of DNA sequences with organismal data (microscopy, functional experiments) and development of databases that link these sources of information remain as major tasks to better understand ciliate diversity, ecological roles, and evolution in the ocean.

Tardigrade stowaways: Literature review of Propyxidium tardigradum (Ciliophora, Peritrichia) and its first record in Scotland.

Tardigrades are a phylum of microscopic invertebrates with a global distribution. Although our understanding of their systematic position and taxonomy has increased and continues to grow, their relationship with the other organisms that share their habitat remains poorly studied. One such organism is Propyxidium tardigradum, a peritrich ciliate which uses tardigrades for dispersion and as a substrate for reproduction. Here, we present the first Scottish record and tenth global occurrence of Propyxidium tardigradum, thereby expanding our knowledge of its poorly understood zoogeographic distribution. We also summarise the literature concerning P. tardigradum biology, proffer hypotheses regarding the Propyxidium-tardigrade relationship, and the apparent lack of heterotardigrade ciliate infestation. Additionally, we indicate a number of recommendations for the direction of future studies regarding the ciliate. Finally, we add a further three species, Milnesium variefidum, Hypsibius cf. scabropygus and Macrobiotus scoticus to the list of Propyxidium host species.

From oral structure to molecular evidence: new insights into the evolutionary phylogeny of the ciliate order Sessilida (Protista, Ciliophora), with the establishment of two new families and new contributions to the poorly studied family Vaginicolidae.

Ciliated protists represent one of the most primitive and diverse lineages of eukaryotes, with nuclear dimorphism, a distinctive sexual process (conjugation), and extensive genome rearrangements. Among divergent ciliate lineages, the peritrich order Sessilida includes members with a colonial lifestyle, which may hint to an independent evolutionary attempt for multicellularity, although they are still single-celled organisms. To date, the evolution and phylogeny of this group are still far from clear, in part due to the paucity of molecular and/or morphological data for many taxa. In this study, we extend taxon sampling of a loricate group of sessilids by obtaining 69 new rDNA (SSU rDNA, ITS1-5.8S rDNA-ITS2, and LSU rDNA) sequences from 20 well-characterized representative species and analyze the phylogenetic relationships within Sessilida. The main findings are: (i) the genera Rhabdostyla and Campanella each represents a unique taxon at family level, supporting the establishment of two new families, i.e., Rhabdostylidae n. fam. and Campanellidae n. fam., respectively, the former being sister to a morphologically heterogeneous clade comprising Astylozoidae and several incertae sedis species and the latter occupying the basal position within the Sessilida clade; (ii) the structure of infundibular polykinety 3 is likely to be a phylogenetically informative character for resolving evolutionary relationships among sessilids; (iii) differences between sparsely and the densely arranged silverline systems could be a suprageneric taxonomic character; (iv) the monophyly of Vaginicolidae is confirmed, which is consistent with its specialized morphology, i.e., the possession of a typical peritrich lorica which might be an apomorphy for this group; (v) within Vaginicolidae, the monotypic Cothurniopsis sensu Stokes, 1893 is a synonym of Cothurnia Ehrenberg, 1831, and a new combination is created, i.e., Cothurnia valvata nov. comb.; (vi) Vaginicola sensu lato comprises at least two distinctly divergent clades, one affiliated with Thuricola and the other with a systematically puzzling clade represented by Vaginicola tincta.

Re-discovery and novel contributions to morphology and multigene phylogeny of Protospirella mazurica (Raabe, 1968) Aescht, 2001 (Ciliophora: Pleuronematida), an obligate symbiont of the river nerite Theodoxus fluviatilis Linnaeus, 1758 (Mollusca: Gastropoda).

Although the river nerite Theodoxus fluviatilis (Gastropoda: Neritimorpha) has an exceptionally broad geographical and ecological distribution, it carries only four ciliate species: Hypocomella quatuor, Protospirella mazurica, Scyphidia sp., and Trichodina baltica. After more than a half-century gap, we re-discovered P. mazurica in a Danubian population of T. fluviatilis (haplotypes F31 and F34) and characterized it using an integrative morpho-molecular approach. Protospirella mazurica is distinguished by (i) a small, elongate-ellipsoidal to ovoidal body, (ii) a broadly ellipsoidal macronucleus accompanied by a single globular micronucleus, (iii) a subterminal contractile vacuole, (iv) about 24 somatic kineties, (v) thigmotactic ciliature composed of about 10 kineties shortened posteriorly to form a parenthetical system, and (vi) a long inverted J-shaped paroral membrane associated with three unequally long membranelles. According to the present phylogenetic analyses of two mitochondrial and three nuclear markers, P. mazurica robustly clusters within the order Pleuronematida (Oligohymenophorea: Scuticociliatia) along with other symbiotic members of the families Hemispeiridae and Thigmophryidae as well as free-living representatives of the paraphyletic family Cyclidiidae. In light of the present phylogenetic analyses, we consider the family Ancistridae to be a junior synonym of the family Hemispeiridae, which collates 14 genera in our classification framework.

Molecular characterization and phylogenetic analysis of Paratrichodina africana Kazubski and El-Tantawy, 1986 based on 18S rRNA gene data with the evolutionary hypothesis of trichodinids.

In this study, we provided the morphological data and the first 18S rRNA gene data of Paratrichodina africana Kazubski and El-Tantawy, 1986, isolated from hybrids of Oreochromis niloticus × Oreochromis mossambicus in Chongqing, China. Morphologically, P. africana is mainly characterized by the triangular blade and prominent anterior projection. The present population is consistent with the original populations in the overall appearance of the adhesive disc, and falls within the morphometry range of the original descriptions. Phylogenetically, P. africana was clustered into one large clade with Trichodinella and Tripartiella species, which was nested within Trichodina ones with strong support. By combining morphological and molecular data, our results revealed that the validity of the genus Paratrichodina was doubtful, and suggested that the three genera Trichodinella, Tripartiella, and Paratrichodina should be incorporated into one independent genus. In addition, we provided morphological and molecular data of additional eight trichodinids, and further performed the phylogenetic analysis and traced the evolution history of trichodinids' five morphological and bionomical characters for the first time by taking advantage of the current GenBank data. According to the present results, one evolutionary hypothesis of trichodinids was proposed as follows. The most recent common ancestor of trichodinids inhabiting the freshwater environment as a symbiont of vertebrates should evolve from the ancestor with a long-spiral adoral ciliary turn. The first differentiated Trichodina species should be parasitic on one vertebrate distributed in the freshwater environment. During their evolution, some trichodinids expanded to the marine environment, and some switched to invertebrates in the freshwater environment. The denticle of some freshwater Trichodina species became narrower, and the adoral ciliary spiral turn got shorter, forming the ancestor-oid organism with a short-spiral adoral ciliary turn. Then, those Trichodinella, Tripartiella, and Paratrichodina species might evolve from those ancestor-oid organisms with short-spiral adoral ciliary turn.

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.

Large-scale phylogenetic analysis provides insights into the diversification and evolution of sessilid peritrich ciliates (Protista: Ciliophora).

The Peritrichia is a speciose and morphologically distinctive assemblage of ciliated protists that was first observed by Antonie van Leeuwenhoek over 340 years ago. In the last two decades, the phylogenetic relationships of this group have been increasingly debated as morphological and molecular analyses have generated contrasting conclusions, mainly owing to limited sampling. In the present study, we performed expanded phylogenetic analyses of 152 sessilid peritrichs collected from 14 different provinces of China and 141 SSU rDNA peritrich sequences from GenBank. The results of the analyses revealed new divergent relationships between and within major clades that challenge the morphological classification of this group including, (1) the recovery of four major phylogenetically divergent clades in the monophyletic order Sessilida, (2) aboral structures such as the stalk and spasmoneme were evolutionary labile, (3) the stalk or/and spasmoneme was lost in each divergent clade indicating that parallel evolution occurred in sessilid peritrichs and (4) the life cycle and habit drive the diversity of aboral structures as well as diversification and evolution in peritrichs.

Ontogenetic and spatial variability in parasite communities of white shrimp Penaeus setiferus (Decapoda: Penaeidae).

Understanding the combined effects of multi-parasite infections on their hosts is necessary for documenting parasite impacts and is particularly important for developing effective management strategies for economically important organisms. The white shrimp Penaeus setiferus supports important recreational and commercial fisheries along the southeastern and Gulf coasts of the United States and occupies an important ecological niche in estuarine and offshore habitats throughout these regions. The goal of this study was to identify and assess ontogenetic and spatial variation in white shrimp parasite communities and their relation to shrimp health. We used a series of trawl surveys in tidal creek and open water habitats of an estuary in the southeastern USA to collect and identify parasites of white shrimp using morphological and DNA sequencing techniques. Parasite communities in white shrimp were composed of organisms belonging to 6 classes: Conoidasida (gregarines), Oligohymenophorea (apostome and sessilid ciliates), Microsporea (meiodihaplophasids), Chromadorea (rhabditids), Cestoda (cyclophyllideans, lecanocephalideans and trypanorhynchs) and Trematoda (plagiorchiids). Parasite communities differed significantly among white shrimp life stages and localities. Furthermore, the health condition known as black gill occurred in some shrimp and was significantly related to parasite community structure. Infection metrics for the apostome ciliate Hyalophysa lynni, the trypanorhynch larvae Prochristianella sp. and the rhabditid larvae Hysterothylacium sp. were significantly different between shrimp exhibiting and not exhibiting black gill. These results highlight the importance of understanding parasite communities and the potential interactive effects of multiple parasite infections on shrimp health.

A checklist of epibiont and parasite ciliates (Ciliophora) associated to rotifers (Rotifera).

A review of the ciliate (Ciliophora) species associated to rotifers as epibionts and endoparasites is presented, based on published records. Thirty rotifer species from 12 genera are known as hosts of ciliates. Among ciliates, one species of class Suctorea and 14 species of class Oligohymenophorea (12 from subclass Peritrichia, one from Hymenostomatia, and one from Astomatia) have been noted as associated to rotifers. The possible factors responsible for host prevalence of ciliates are discussed.