MOLECULAR IDENTIFICATION OF JUVENILE NEOECHINORHYNCHUS SPP. (PHYLUM: ACANTHOCEPHALA) INFECTING OSTRACOD AND SNAIL HOSTS PROVIDES INSIGHT INTO ACANTHOCEPHALAN HOST USE.

The role of invertebrates in some acanthocephalan life cycles is unclear because juvenile acanthocephalans are difficult to identify to species using morphology. Most reports suggest acanthocephalans from turtle definitive hosts use ostracods as intermediate hosts and snails as paratenic hosts. However, laboratory studies of the life cycle suggest that ostracods and snails are both required hosts in the life cycle. To elucidate the role of ostracods and snails in acanthocephalan life cycles better, we collected 558 freshwater snails of 2 species, including Planorbella cf. Planorbella trivolvis and Physa acuta, from 23 wetlands in Oklahoma, U.S.A., and examined them for acanthocephalan infections. Additionally, we examined 37,208 ostracods of 4 species, Physocypria sp. (morphotype 1), Cypridopsis sp., Stenocypris sp., and Physocypria sp. (morphotype 2) for juvenile acanthocephalans from 2 wetlands in Oklahoma. Juvenile acanthocephalans were morphologically characterized, and the complete internal transcribed spacer (ITS) region of nuclear rDNA was sequenced from acanthocephalans infecting 11 ostracod and 13 snail hosts. We also sampled 10 red-eared slider turtles, Trachemys scripta elegans, and 1 common map turtle, Graptemys geographica, collected from Oklahoma, Arkansas, and Texas and recovered 1,854 adult acanthocephalans of 4 species. The ITS of 17 adult acanthocephalans of 4 species from turtle hosts were sequenced and compared to juvenile acanthocephalan sequences from ostracod and snail hosts from this study and GenBank to determine conspecificity. Of the 23 locations sampled for snails, 7 (30%) were positive for juvenile acanthocephalans in the genus Neoechinorhynchus. The overall prevalence and mean intensity of acanthocephalans in Planorbella cf. P. trivolvis and P. acuta were 20% and 2 (1-6) and 2% and 1 (1), respectively. In contrast, only 1 of 4 species of ostracods, Physocypria sp. (morphotype 1), was infected with larval/juvenile Neoechinorhynchus spp. with an overall prevalence of 0.1% and a mean intensity of 1 (1-2). Although 4 species of acanthocephalans infected turtle definitive hosts, including Neoechinorhynchus chrysemydis, Neoechinorhynchus emydis, Neoechinorhynchus emyditoides, and Neoechinorhynchus pseudemydis, all the ITS sequences from cystacanths infecting snail hosts were conspecific with N. emydis. In contrast, the ITS sequences from larval/juvenile acanthocephalans from ostracods were conspecific with 2 species of acanthocephalans from turtles (N. emydis and N. pseudemydis) and 1 species of acanthocephalan from fish (Neoechinorhynchus cylindratus). These results indicate that N. emydis infects freshwater snails, whereas other species of Neoechinorhynchus appear not to infect snail hosts. We document new ostracod and snail hosts for Neoechinorhynchus species, including the first report of an ostracod host for N. pseudemydis, and we provide novel molecular barcodes that can be used to determine larva, juvenile, and adult conspecificity of Neoechinorhynchus species.

Invasive Non-Native Crustacean Symbionts: Diversity and Impact.

Invasive non-native species (INNS) pose a risk as vectors of parasitic organisms (Invasive Parasites). Introducing invasive parasites can result in ecological disturbances, leading to biodiversity loss and native species illness/mortality, but occasionally can control INNS limiting their impact. Risks to human health and the economy are also associated with INNS and invasive parasites; however, we understand little about the diversity of symbiotic organisms co-invading alongside INNS. This lack of clarity is an important aspect of the 'One Health' prerogative, which aims to bridge the gap between human, wildlife, and ecosystem health. To explore symbiont diversity associated with the invasive crustacean group (including: crab, lobster, crayfish, shrimp, amphipod, isopod, copepod, barnacle, other) (n = 323) derived from 1054 aquatic invertebrates classed as INNS across databases, we compile literature (year range 1800-2017) from the native and invasive range to provide a cumulative symbiont profile for each species. Our search indicated that 31.2% of INN crustaceans were known to hold at least one symbiont, whereby the remaining 68.8% had no documented symbionts. The symbiont list mostly consisted of helminths (27% of the known diversity) and protists (23% of the known diversity), followed by bacteria (12%) and microsporidians (12%). Carcinus maenas, the globally invasive and extremely well-studied green crab, harboured the greatest number of symbionts (n = 72). Additional screening is imperative to become more informed on invasive symbiont threats. We reveal that few studies provide truly empirical data that connect biodiversity loss with invasive parasites and suggest that dedicated studies on available systems will help to provide vital case studies. Despite the lack of empirical data, co-invasive parasites of invasive invertebrates appear capable of lowering local biodiversity, especially by causing behavioural change and mortality in native species. Alternatively, several invasive parasites appear to protect ecosystems by controlling the impact and population size of their invasive host. We provide a protocol that could be followed to explore symbiont diversity in invasive groups as part of our case studies. The consequence of limited parasite screening of INNS, in addition to the impacts invasive parasites impart on local ecologies, are explored throughout the review. We conclude in strong support of the 'One Health' prerogative and further identify a need to better explore disease in invasion systems, many of which are accountable for economic, human health and ecological diversity impacts.

Risk factors and prevalence of enteroparasitic diseases in shellfish pickers from a lake area in the Northeast of Brazil / Fatores de risco e prevalência de enteroparasitoses em marisqueiras de uma região lagunar no Nordeste do Brasil

INTRODUCTION: Intestinal parasitosis are a public health problem worldwide. There are several risk factors and a high association with some specific labor activities. OBJECTIVE: The present study assessed the risk factors and prevalence of enteroparasitic diseases in shellfish pickers from one district of Maceió, Alagoas state, Brazil. METHODS: Crosssectional study of 41 female shellfish pickers including parasitological tests in fecal samples and a questionnaire with objective and subjective questions. Sand samples from their working environment were also analyzed. RESULTS: At least one species of parasite was found in 19.51% of the fecal samples. Pathogenic species of Giardia lamblia, Trichuris trichiura, Schistosoma mansoni, Ascaris lumbricoides, Enterobius vermicularis, from the Ancylostomatidae family, and non-pathogenic species of Entamoeba coli were found. Polyparasitism was diagnosed in 37.5% of the positive samples. A total of 57.14% of sand samples contained hookworm larvae. Regarding the risk factor, low educational level was statistically associated to the presence of parasites (p<0.05). CONCLUSION: Greater investment in basic education is needed to increase the knowledge about preventive measures against parasitic diseases and the promotion food-handling courses in order to change existing inadequate habits in the community. Basic sanitation is also essential in preventing environmental contamination.

INTRODUÇÃO: As parasitoses intestinais representam um problema de saúde pública mundial. Estão associados inúmeros fatores de risco, bem como atividades laborais específicas. OBJETIVO: O presente estudo avaliou os fatores de risco e a prevalência de enteroparasitoses em marisqueiras de um bairro da cidade de Maceió, Alagoas, Brasil. MÉTODOS: Procedeu-se um estudo de corte transversal, sendo 41 marisqueiras avaliadas mediante exame parasitológico de fezes e questionário contendo questões discursivas e de múltipla escolha. Foram analisadas também amostras de areia do ambiente de trabalho das mesmas. RESULTADOS: A positividade para pelo menos uma espécie de parasito nas fezes foi de 19,51%. Foram encontradas as espécies patogênicas Giardia lamblia, Trichuris trichiura, Schistosoma mansoni, Ascaris lumbricoides, Enterobius vermicularis e da família Ancylostomatidae, e a espécie não patogênica, Entamoeba coli. Poliparasitismo foi diagnosticado em 37,5% dos exames positivos. Um total de 57,14% das amostras de areia continha larvas de ancilostomatídeos. Em relação aos fatores de risco, a baixa escolaridade foi estatisticamente associada à presença de parasitas (p<0,05). CONCLUSÃO: É necessário maior investimento na educação básica para aprimorar o conhecimento das formas de prevenção das parasitoses e a promoção de cursos de boas práticas de manipulação de alimentos, a fim de modificar hábitos errôneos já incorporados na comunidade. O saneamento básico também é fundamental para evitar contaminação ambiental.

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.

Parasites shape community structure and dynamics in freshwater crustaceans.

Parasites directly and indirectly influence the important interactions among hosts such as competition and predation through modifications of behaviour, reproduction and survival. Such impacts can affect local biodiversity, relative abundance of host species and structuring of communities and ecosystems. Despite having a firm theoretical basis for the potential effects of parasites on ecosystems, there is a scarcity of experimental data to validate these hypotheses, making our inferences about this topic more circumstantial. To quantitatively test parasites' role in structuring host communities, we set up a controlled, multigenerational mesocosm experiment involving four sympatric freshwater crustacean species that share up to four parasite species. Mesocosms were assigned to either of two different treatments, low or high parasite exposure. We found that the trematode Maritrema poulini differentially influenced the population dynamics of these hosts. For example, survival and recruitment of the amphipod Paracalliope fluviatilis were dramatically reduced compared to other host species, suggesting that parasites may affect their long-term persistence in the community. Relative abundances of crustacean species were influenced by parasites, demonstrating their role in host community structure. As parasites are ubiquitous across all communities and ecosystems, we suggest that the asymmetrical effects we observed are likely widespread structuring forces.

Hematodinium spp. infections in wild and cultured populations of marine crustaceans along the coast of China.

The parasitic dinoflagellate Hematodinium spp. infects a broad range of marine crustaceans. Its epidemics have impacted wild populations of various commercial fishery species around the world and the sustainability of mariculture in China. To study the epidemiology of Hematodinium spp. in marine crustaceans along the coast of China, we conducted a broad survey of wild and cultured stocks of major crustacean species in 2013 to 2015. Hematodinium sp. infections were identified in wild stocks of Portunus trituberculatus from Huludao, Laizhou, Qingdao, Yangtze River Estuary and Zhoushan, and Scylla paramamosain from Shantou; and cultured stocks of Portunus trituberculatus and Penaeus monodon from a polyculture pond in Qingdao. In the polyculture pond, Hematodinium sp. infections were observed in Portunus trituberculatus from June until October, with peak prevalence (up to 90%) observed in late July to early August. Furthermore, Hematodinium sp. infection was identified for the first time in the giant tiger prawn Penaeus monodon in the polyculture system during the disease outbreak. Phylogenetic analysis indicated that the Hematodinium isolate infecting Penaeus monodon was identical to the isolate infecting the co-cultured Portunus trituberculatus, and it was grouped into H. perezi genotype II together with the other isolates reported in China. The Hematodinium sp. isolated from Portunus trituberculatus appeared to have similar life stages as the H. perezi genotype III isolated from the American blue crab Callinectes sapidus. Our study indicates that outbreaks of Hematodinium disease can be a significant threat to the widely used polyculture system for decapods in China that may be particularly vulnerable to such generalist pathogens.

Diagnóstico e incidencia de enfermedades bacterianas y parasitarias que afectan el cultivo de camarón marino en estanques del sector El Zompopero y Salinas del Potrero, municipio de Jiquilísco, departamento de Usulután: en vínculo con Cooperativas de San Hilario / Diagnosis and incidence of bacterial and parasitic diseases that affect the cultivation of marine shrimp in ponds of El Zompopero and Salinas del Potrero sectors, municipality of Jiquilísco, department of Usulután: in connection with cooperatives of San Hilario

Las enfermedades bacterianas y parasitarias pueden llegar a comprometer los niveles de sobrevivencia de un cultivo de camarón marino. La frecuencia de aparición de camarones muertos en las orillas de los estanques o que aparecen en las atarrayas, son solo un signo o señal de que algo marcha mal en el estanque. Cuando los camarones están sometidos a factores estresantes se reducen su actividad limpiadora, no mudan y por tanto, son altamente susceptibles a la invasión de ectoparásitos. En grados de severidad 3 y 4 de la infestación por ectoparásitos en la superficie corporal del camarón, trae como consecuencia dificultades en la locomoción, la alimentación, la respiración, y finalmente sobreviene la muerte. Por otra parte, las enfermedades de origen bacteriano reportados en los sistemas de cultivo causadas por el género Vibrio, ha llegado a ser la enfermedad económicamente más importante en el cultivo de organismos marinos, afectando un gran número de especies; es catalogada como la causa de serias pérdidas económicas en la producción de camarón de cultivo en diversos países.

Bacterial and parasitic diseases can compromise the survival levels of a marine shrimp culture. The frequency of the appearance of dead shrimp on the banks of the ponds or that appear on the cast nets, are just a sign that something is wrong in the pond. When shrimp are subjected to stress, their cleaning activity is reduced, they do not molt and therefore are highly susceptible to invasion by ectoparasites. In degrees of severity 3 and 4, the infestation by ectoparasites on the body surface of the shrimp, results in difficulties in locomotion, feeding, breathing, and finally, death ensues. On the other hand, the diseases of bacterial origin reported in culture systems caused by the Vibrio genus have become the most economically important disease in the cultivation of marine organisms, affecting a large number of species; It is classified as the cause of serious economic losses in the production of farmed shrimp in various countries.

Smelling the future: subtle life-history adjustments in response to environmental conditions and perceived transmission opportunities in a trematode.

A number of parasites with complex life cycles can abbreviate their life cycles to increase the likelihood of reproducing. For example, some trematodes can facultatively skip the definitive host and produce viable eggs while still inside their intermediate host. The resulting shorter life cycle is clearly advantageous when transmission probabilities to the definitive hosts are low. Coitocaecum parvum can mature precociously (progenesis), and produce eggs by selfing inside its amphipod second intermediate host. Environmental factors such as definitive host density and water temperature influence the life-history strategy adopted by C. parvum in their crustacean host. However, it is also possible that information about transmission opportunities gathered earlier in the life cycle (i.e. by cercariae-producing sporocysts in the first intermediate host) could have priming effects on the adoption of one or the other life strategy. Here we document the effects of environmental parameters (host chemical cues and temperature) on cercarial production within snail hosts and parasite life-history strategy in the amphipod host. We found that environmental cues perceived early in life have limited priming effects on life-history strategies later in life and probably account for only a small part of the variation among conspecific parasites. External cues gathered at the metacercarial stage seem to largely override potential effects of the environmental conditions experienced by early stages of the parasite.

The phylogeny and life cycle of two species of Profilicollis (Acanthocephala: Polymorphidae) in marine hosts off the Pacific coast of Chile.

Resolving complex life cycles of parasites is a major goal of parasitological research. The aim of this study was to analyse the life cycle of two species of the genus Profilicollis, the taxonomy of which is still unstable and life cycles unclear. We extracted individuals of Profilicollis from two species of crustaceans (intermediate hosts) and four species of seagulls (definitive hosts) from sandy-shore and estuarine habitats along the south-east Pacific coast of Chile. Mitochondrial DNA analyses showed that two species of Profilicollis infected intermediate hosts from segregated habitats: while P. altmani larvae infected exclusively molecrabs of the genus Emerita from fully marine habitats, P. antarcticus larvae infected the crab Hemigrapsus crenulatus from estuarine habitats. Moreover, P. altmani completed its life cycle in four seagulls, Chroicocephalus maculipennis, Leucopheus pipixcan, Larus modestus and L. dominicanus, while P. antarcticus, on the other hand, completed its life cycle in the kelp gull L. dominicanus. Accordingly, our results show that two congeneric parasites use different and spatially segregated species as intermediate hosts, and both are capable of infecting one species of definitive hosts. As such, our analyses allow us to shed light on a complex interaction network.

Hyperspora aquatica n.gn., n.sp. (Microsporidia), hyperparasitic in Marteilia cochillia (Paramyxida), is closely related to crustacean-infecting microspordian taxa.

The Paramyxida, closely related to haplosporidians, paradinids, and mikrocytids, is an obscure order of parasitic protists within the class Ascetosporea. All characterized ascetosporeans are parasites of invertebrate hosts, including molluscs, crustaceans and polychaetes. Representatives of the genus Marteilia are the best studied paramyxids, largely due to their impact on cultured oyster stocks, and their listing in international legislative frameworks. Although several examples of microsporidian hyperparasitism of paramyxids have been reported, phylogenetic data for these taxa are lacking. Recently, a microsporidian parasite was described infecting the paramyxid Marteilia cochillia, a serious pathogen of European cockles. In the current study, we investigated the phylogeny of the microsporidian hyperparasite infecting M. cochillia in cockles and, a further hyperparasite, Unikaryon legeri infecting the digenean Meiogymnophallus minutus, also in cockles. We show that rather than representing basally branching taxa in the increasingly replete Cryptomycota/Rozellomycota outgroup (containing taxa such as Mitosporidium and Paramicrosoridium), these hyperparasites instead group with other known microsporidian parasites infecting aquatic crustaceans. In doing so, we erect a new genus and species (Hyperspora aquatica n. gn., n.sp.) to contain the hyperparasite of M. cochillia and clarify the phylogenetic position of U. legeri. We propose that in both cases, hyperparasitism may provide a strategy for the vectoring of microsporidians between hosts of different trophic status (e.g. molluscs to crustaceans) within aquatic systems. In particular, we propose that the paramyxid hyperparasite H. aquatica may eventually be detected as a parasite of marine crustaceans. The potential route of transmission of the microsporidian between the paramyxid (in its host cockle) to crustaceans, and, the 'hitch-hiking' strategy employed by H. aquatica is discussed.

Harpacticoid copepods-their symbiotic associations and biogenic substrata: a review.

Members of the order Harpacticoida are primarily free-living and benthic but some lineages have adopted alternative modes of life which involve a major habitat shift or dependence on a host. Since the first discovery of a harpacticoid associated with an invertebrate host about 150 years ago, a total of 172 species, representing 84 genera and 17 families, have been shown to live in symbiotic partnership with other organisms. The steady addition of new taxa during the last 35 years testifies to the widespread and previously underestimated occurrence of symbiosis in the group. Harpacticoids have entered into associations with Cyanobacteria, Protozoa, macroalgae, grasses, fish hosts, marine tetrapods (including whales, sea turtles and manatees) and at least eleven invertebrate phyla. At present, 86 independent colonizations of marine and freshwater host organisms can be identified but this number is a minimum estimate and is expected to increase as certain host groups will be more properly sampled. In contrast to the Cyclopoida and Siphonostomatoida, which have been extremely successful in developing associations with cnidarians, sponges, echinoderms and ascidiaceans, members of the Harpacticoida have a marked predilection for crustacean hosts. Except for a few species that can be classified as genuine parasites, the precise nature of the relationship between most associated harpacticoids and their hosts has yet to be elucidated but can probably be defined as commensalistic, where the benefit to the copepod may be nutritional or protective. Most are ectosymbiotic but some live as endocommensals in microhabitats which provide considerable protection from predation. The success of symbiotic harpacticoids in freshwater is limited with the few species known to be associated with freshwater hosts typically representing isolated forays into a symbiotic lifestyle from an otherwise free-living lineage. The scattered literature on symbiotic harpacticoids is compiled and presented by host group. Dichotomous keys are provided for the identification of most species while accidental and doubtful records are discussed where appropriate.The genus Idomenella T. Scott, 1906a (Pseudotachidiidae), previously a junior subjective synonym of Dactylopodella Sars, 1905a, is reinstated to accommodate Dactylopodella rostrata (T. Scott, 1893), D. janetae Hicks, 1989, Xouthous coronatus (T. Scott, 1894b), X. antarcticus (Giesbrecht, 1902), X. intermedius (Lang, 1934) and Idomenella paracoronata sp. nov. Kioloaria Harris, 1994 (Porcellidiidae) is adopted as the valid replacement name for the preoccupied Acutiramus Harris, 2014a. The name of a second porcellidiid genus, Murramia Harris, 1994, lacks the mandatory type fixation and is made available here by adopting the original name but taking the present authorship and date. The generic name Ellucana Sewell, 1940 is currently unavailable and must instead be attributed to Coull (1971b). Laophonte commensalis Raibaut, 1962a is fixed as the type of Raibautius gen. nov. in the family Laophontidae, Tegastes cnidicus Humes, 1981b as the type of Aglaogastes gen. nov. in the Tegastidae, and Canuella (Canuella) indica Krishnaswamy, 1957 as the type of Indicanuella gen. nov.A number of new names are proposed for species that had previously been misidentified: Diarthrodes septemtrionalis sp. nov. for D. roscoffensis (Monard, 1935b) sensu Kornev & Chertoprud (2008), Kioloaria jejuensis sp. nov. for Porcellidium brevicaudatum Thompson & Scott, 1903 sensu Kim & Kim (1996), Xouthous andamanensis sp. nov. for X. maldivae [sic] Sewell, 1940 sensu Wells & Rao (1987), X. wellsi sp. nov. for X. laticaudatus (Thompson & Scott, 1903) sensu Wells (1967), X. namibiensis sp. nov. for X. pectinatus (Scott & Scott, 1898) sensu Kunz (1963), and Idomenella paracoronata sp. nov. for Idomene coronata (T. Scott, 1894b) sensu Sars (1909a). The inadequately described Amenophia ovalis Brady, 1910 is relegated to a species inquirenda in Amenophia Boeck, 1865. Idomene australis Brady, 1910, I. pusilla Brady, 1910, Dactylopusia ferrieri T. Scott, 1912 and I. kabylica Monard, 1936 are ranked species incertae sedis in the Pseudotachidiidae. Dactylopus bahamensis Edwards, 1891 is tentatively considered as species incertae sedis in the Dactylopusiidae. Canuellina onchophora Por, 1967 and C. nicobaris Wells & Rao, 1987 are transferred to the genus Ellucana Coull, 1971b while Ellucana secunda Coull, 1971b is assigned to the genus Canuellina Gurney, 1927. Xylora calyptogenae Willen, 2006 is sunk as a junior subjective synonym of X. bathyalis Hicks, 1988a. The incorrect original spellings of Parathalestris pacificus Chislenko, 1971, P. infestus Ho & Hong, 1988, Tripartisoma ovalis Avdeev, 1983, T. trapezoidalis Avdeev, 1983, Amplipedicola pectinatus Avdeev, 2010 and Sunaristes japonicus Ho, 1986a are amended to reflect agreement in gender with their respective generic names.

Genetic Variations of the Parasitic Dinoflagellate Hematodinium Infecting Cultured Marine Crustaceans in China.

The parasitic dinoflagellate Hematodinium infects multiple cultured marine crustaceans and has resulted in significant economic losses to their aquaculture in China. Limited molecular data implied a close relationship among Hematodinium reported in China, whereas the genetic diversity and detailed genetic variation within Hematodinium remains unclear. In order to investigate the genetic diversity and composition of the parasitic dinoflagellate in China, the sequences of the internal transcribed spacer region (ITS1 - 5.8S - ITS2) were amplified from 104 infected hosts cultured in three geographic locations. Two strains were identified, Hematodinium perezi II was the prevalent strain observed in all three host taxa throughout the survey, the other novel one was detected from the single Exopalaemon carinicauda collected from Zhejiang province. Eight ITS haplotypes within H. perezi II were identified with a similarity of 99.8% -100%. The distinct haplotype compositions and AMOVA analysis suggested a significant genetic differentiation and population structure among the three geographic populations of H. perezi II. The novel strain, genetically affiliated with H. perezi, was quite divergent from the three known genotypes (I, II and III) of H. perezi, and further investigation is needed to determine the distribution and host range of this new strain.

Evaluating the Biological and Ecological Factors Influencing Transmission of Larval Digenetic Trematodes: A Test of Second Intermediate Host Specificity of Two North American Halipegus Species.

Host specificity of parasites is a basic principle in parasitology; however, it is not easily measured. Previously, host specificity was calculated as the number of species that a parasite infected, but this is not an accurate description of host usage because some species are capable of being infected but do not contribute to the completion of the life cycle. Instead, measures of host specificity should take into consideration interactions between a parasite and a potential host species as well as interactions between current and subsequent hosts in the life cycle. The objectives of this study were to track the development of 2 trematode species, Halipegus eccentricus and Halipegus occidualis , in 3 phylogenetically and ecologically distinct microcrustacean second intermediate hosts, and then evaluate the extent to which each of these hosts contributed to transmission of each Halipegus species to the next odonate host in the life cycle. All 3 microcrustacean species exposed became infected with both species of Halipegus. The patterns of growth of H. eccentricus and H. occidualis were similar, but there were consistent differences in the rates of growth among the microcrustacean species in both Halipegus species. Regardless of host species infected, all individuals of both species were considered to be developmentally infective to the next host in the life cycle by 19 days postexposure (DPE) when they lost their excretory bladder. Worms of varying sizes were capable of surviving without this structure, suggesting that there is not a strong relationship between the rate of growth of the metacercariae and the development of their osmoregulatory system. Although Halipegus species were capable of living without an excretory bladder at 19 DPE, there were differences in their size and rates at which the 3 microcrustaceans contributed to transmission of the parasites to subsequent odonate hosts. Collectively, under controlled laboratory conditions, there was an approximate 2-fold difference in the average percentage of worms that established in odonates from the ostracod, Cypridopsis sp., than from the harpacticoid copepod, Phyllognathopus sp., and the difference was nearly 3-fold between Cypridopsis sp. and the cyclopoid copepod, Thermocyclops sp. Therefore, despite all 3 microcrustacean species becoming infected, not all species were equally suited for transmission and completion of the life cycle. Differences among the 3 microcrustacean species in cercaria ingestion, metacercarial growth and development, and odonate predation rates on infected microcrustacean species were important factors in determining transmission of the 2 Halipegus species to odonate hosts.

A new phylogeny and environmental DNA insight into paramyxids: an increasingly important but enigmatic clade of protistan parasites of marine invertebrates.

Paramyxida is an order of rhizarian protists that parasitise marine molluscs, annelids and crustaceans. They include notifiable pathogens (Marteilia spp.) of bivalves and other taxa of economic significance for shellfish production. The diversity of paramyxids is poorly known, particularly outside of commercially important hosts, and their phylogenetic position is unclear due to their extremely divergent 18S rDNA sequences. However, novel paramyxean lineages are increasingly being detected in a wide range of invertebrate hosts, and interest in the group is growing, marked by the first 'Paramyxean Working Group' Meeting held in Spain in February 2015. We review the diversity, host affiliations, and geographical ranges of all known paramyxids, present a comprehensive phylogeny of the order and clarify its taxonomy. Our phylogenetic analyses confirm the separate status of four genera: Paramarteilia, Marteilioides, Paramyxa and Marteilia. Further, as including M. granula in Marteilia would make the genus paraphyletic we suggest transferring this species to a new genus, Eomarteilia. We present sequence data for Paramyxa nephtys comb. n., a parasite of polychaete worms, providing morphological data for a clade of otherwise environmental sequences, sister to Marteilioides. Light and electron microscopy analyses show strong similarities with both Paramyxa and Paramyxoides, and we further discuss the validity of those two genera. We provide histological and electron microscopic data for Paramarteilia orchestiae, the type species of that genus originally described from the amphipod Orchestia; in situ hybridisation shows that Paramarteilia also infects crab species. We present, to our knowledge, the first known results of a paramyxid-specific environmental DNA survey of environmental (filtered water, sediment, etc.) and organismally-derived samples, revealing new lineages and showing that paramyxids are associated with a wider range of hosts and habitat types than previously known. On the basis of our new phylogeny we propose phylogenetic hypotheses for evolution of lifecycle and infectivity traits observed in different paramyxid genera.

On a New Species of Parasitic Barnacle (Crustacea: Rhizocephala), Sacculina shiinoi sp. nov., Parasitizing Japanese Mud Shrimps Upogebia spp. (Decapoda: Thalassinidea: Upogebiidae), Including a Description of a Novel Morphological Structure in the Rhizocephala.

The rhizocephalan Sacculina shiinoi sp. nov. parasitizes three species of Upogebia in Japan. It is described morphologically and compared with another Upogebia parasite, Sacculina upogebiae Shiino, 1943 from Japan and Korea. These two species are the only sacculinids that parasitize mud shrimps. DNA analyses clearly show the two species to be separate and not closely related. The cuticle differs in being provided with close-set, branched, and spiny excrescences in S. shiinoi, while it lacks excrescences, but forms small scales in S. upogebiae. In S. upogebiae, the bulbous sperm-producing part and the narrow receptacle duct are separated by a compartmentalized mid portion, which is missing in S. shiinoi. A ridge, having a thickened, fluffy cuticle with a U-shaped course, passes across the visceral mass between the two receptacle openings in S. shiinoi. Such a structure has never been described in other rhizocephalans, and its function is uncertain.

Descriptions of two new species of Rhizorhina Hansen, 1892 (Copepoda: Siphonostomatoida: Nicothoidae) parasitic on tanaidacean crustaceans, with a note on their phylogenetic position.

Two new species of nicothoid copepod are described. Rhizorhina ohtsukai n. sp. found on a leptocheliid (Leptochelia sp.) collected at depths of 151-136 m in the North Pacific Ocean is most similar to Rhizorhina aesthetes Boxshall & Harrison, 1988 but can be distinguished by the possession of a narrower body with a rounded anterior end, and in the position of the gonopores. Rhizorhina soyoae n. sp. found on an apseudid (Fageapseudes sp.) collected at depths of 1,595-1,557 m in East China Sea most closely resembles Rhizorhina tanaidaceae Gotto, 1984 but differs in having a narrower body with a rounded anterior end. Partial nucleotide sequences of the cytochrome c oxidase subunit I (COI) gene were obtained from the two copepods in order to enable future barcoding. A phylogenetic reconstruction based on the 18S rRNA gene placed the copepods within the Siphonostomatoida Burmeister, 1835, with the nicothoid Choniosphaera maenadis (Bloch & Gallien, 1933), and separate from the Rhizorhina spp. clade, suggesting that the family Nicothoidae Dana, 1849 is not monophyletic. This is the third report of copepods parasitic on tanaidacean crustaceans.

Atrazine reduces the transmission of an amphibian trematode by altering snail and ostracod host-parasite interactions.

Trematodes are ubiquitous members of aquatic environments, have many functional roles in ecosystems, and can cause diseases in humans, livestock, and wild animals. Despite their importance and reports of parasite population declines, few studies have concurrently assessed the effects of aquatic contaminants on multiple hosts, multiple parasite life cycle stages, and on transmission-related host-parasite interactions. Here, we test the effects of environmentally relevant concentrations of the herbicide atrazine (0, 3, 30 µg/L) on the establishment and development of an amphibian trematode (Halipegus eccentricus) in a first-intermediate snail host (Physa acuta) and in a second-intermediate ostracod host (Cypridopsis sp.). Additionally, we test the interactive effects of atrazine and parasitism on snail and ostracod survival. Our results indicate that atrazine negatively affects trematode transmission by altering snail and ostracod host-parasite interactions. Although atrazine did not affect the survival of uninfected snails alone, atrazine acted synergistically with parasitism to reduce the longevity of infected snails. As a result, the number of cercariae (i.e., larval trematodes) produced by snails was 50.7 % (3 µg/L) and 14.9 % (30 µg/L) relative to controls. Atrazine exhibited direct negative effects on ostracod survival at 30 µg/L. However, when ostracods were also exposed to trematodes, the negative effects of atrazine on survival were diminished. Although infected ostracod survival remained high, trematode development was significantly reduced, resulting in reduced infectivity of metacercariae (i.e., nongravid adult cysts infective to definite host) to 32.2 % (3 µg/L) and 28.6 % (30 µg/L) relative to the controls. The combination of reduced cercaria production and reduced metacercarial infectivity in the 3 and 30 µg/L atrazine treatment groups reduced the net number of infective worms produced to 16.4 and 4.3 % (respectively) relative to the control. These results demonstrate the complex nature of pesticide effects on trematode infections and indicate that trematodes can affect their first- and second-intermediate hosts differently under different pesticide concentrations. Our work has broad implications for parasite transmission and conservation and provides a testable mechanism for understanding trematode population declines in contaminated wetlands.

Fossil Crustaceans as Parasites and Hosts.

Numerous crustacean lineages have independently moved into parasitism as a mode of life. In modern marine ecosystems, parasitic crustaceans use representatives from many metazoan phyla as hosts. Crustaceans also serve as hosts to a rich diversity of parasites, including other crustaceans. Here, we show that the fossil record of such parasitic interactions is sparse, with only 11 examples, one dating back to the Cambrian. This may be due to the limited preservation potential and small size of parasites, as well as to problems with ascribing traces to parasitism with certainty, and to a lack of targeted research. Although the confirmed stratigraphic ranges are limited for nearly every example, evidence of parasitism related to crustaceans has become increasingly more complete for isopod-induced swellings in decapods so that quantitative analyses can be carried out. Little attention has yet been paid to the origin of parasitism in deep time, but insight can be generated by integrating data on fossils with molecular studies on modern parasites. In addition, there are other traces left by parasites that could fossilize, but have not yet been recognized in the fossil record.

Spatial covariation of local abundance among different parasite species: the effect of shared hosts.

Within any parasite species, abundance varies spatially, reaching higher values in certain localities than in others, presumably reflecting the local availability of host resources or the local suitability of habitat characteristics for free-living stages. In the absence of strong interactions between two species of helminths with complex life cycles, we might predict that the degree to which their abundances covary spatially is determined by their common resource requirements, i.e. how many host species they share throughout their life cycles. We test this prediction using five trematode species, all with a typical three-host cycle, from multiple lake sampling sites in New Zealand's South Island: Stegodexamene anguillae, Telogaster opisthorchis, Coitocaecum parvum, Maritrema poulini, and an Apatemon sp. Pairs of species from this set of five share the same host species at either one, two, or all three life cycle stages. Our results show that when two trematode species share the same host species at all three life stages, they show positive spatial covariation in abundance (of metacercarial and adult stages) across localities. When they share hosts at two life stages, they show positive spatial covariation in abundance in some cases but not others. Finally, if two trematode species share only one host species, at a single life stage, their abundances do not covary spatially. These findings indicate that the extent of resource sharing between parasite species can drive the spatial match-mismatch between their abundances, and thus influence their coevolutionary dynamics and the degree to which host populations suffer from additive or synergistic effects of multiple infections.