Parasitic Copepod Research Articles

The occurrence of parasitic copepods and isopods infesting the marine teleost fishes of Kerala coast, India

The present study reports the occurrence of parasitic copepods and isopods infecting marine teleost fishes from the Kerala coast, India. A total of 1795 fishes belonging to 38 species were collected from the fish landing centres across the Kerala Coast for 5 months. The isopod & copepod infection status of these fishes were assessed. The incidents of site-specific infection were documented for all parasites and a fecundity analysis was conducted in randomly selected species. The single or multiple parasitic crustacean infestation and host preference (single or multiple hosts) were also documented. A total of 32 species of copepods and 6 species of isopod were sourced out. However, the maximum prevalence was recorded for the family Lernanthropidae (71.43%) and the maximum intensity (14) was recorded for a Caligid copepod Euryphorus nordmannii. The predominantly targeted region of infection on the host fish appeared to be gill filament (52.15%). The fecundity showed significant differences between the tested species. Fourteen species of fishes showed multiple parasitic crustacean infestation and eight species of parasites infected multiple hosts. The present study demonstrates that over 68% of marine fish species of Kerala coast were under heavy infection either by isopods or copepods.

Caligus madeirensis sp. nov. (Copepoda: Caligidae) Parasitic on Pompano, Trachinotus ovatus (Linnaeus, 1758), from Eastern Atlantic Waters, Surrounding the Madeira Archipelago, Portugal

IntroductionA new species of the genus Caligus is described based on specimens collected from pompano, Trachinotus ovatus (Linnaeus), caught in eastern Atlantic waters, near the Madeira archipelago.MethodsPompano (n = 21) were purchased from the local fish market and examined for parasitic copepods. Morphological features of the copepods were examined and drawn using an Olympus BX51 equipped with a drawing tube. Key diagnostic characters were scanned using a confocal laser scanning microscope and a scanning electron microscope.ResultsCaligus madeirensis sp. nov., can be distinguished from all congeners (270 spp.) by the combination of the following characters: (i) an accessory process on the 3 outer terminal spines located on the distal exopodal segment of leg 1, (ii) a mandible with 14 teeth, (iii) a sternal furca with parallel, spatulate tines, (iv) a maxilliped with 2 simple setae at base of a claw, (v) a leg 3 with second endopodal segment with 5 pinnate setae, (vi) a 2-segmented leg 4 exopod with I; III spine formula, (vii) a male antenna with 4 overlapping plates on the distal segment, (viii) a male maxilliped corpus bearing a prominent myxal process ornamented with dense corrugations along inner margin.ConclusionTogether with Caligus madeirensis sp. nov., the Caligus fauna of Portugal consists of 13 species reported from 17 Portuguese marine fishes. Considering the large number of marine fish species (510 spp.) currently recorded from Portuguese waters it seems that only 3.3% of the Portuguese marine fishes have been found to be infested with species of the genus Caligus O.F. Müller, 1758, the result of which, however, might be due to limited sampling.Electronic supplementary materialThe online version of this article (10.1007/s11686-020-00290-3) contains supplementary material, which is available to authorized users.

Introduced marine ecosystem engineer indirectly affects parasitism in native mussel hosts

The alteration of habitat structure by introduced ecosystem engineers imposes direct impacts on native biota but can also exert trait-mediated indirect effects. In this study, we show that the habitat structure provided by invasive Pacific oysters (Crassostrea gigas) can also indirectly affect parasitism in native blue mussels (Mytilus edulis). We conducted a 3-month field experiment, in which uninfected mussels were positioned at the bottom and top of two intertidal oyster reefs in the Wadden Sea. On one reef, we detected a significantly higher prevalence of parasitic copepods (Mytilicola spp.) in mussels positioned on top of oysters than in mussels at the bottom, but no difference in infection intensity. For trematodes (Renicola roscovita), a different pattern was observed, with higher prevalence (one reef) and significantly higher infection intensities (both reefs) in mussels positioned at the bottom of the oyster reef. We suggest that the contrasting pattern results from differences in parasite life cycles. Mytilicola spp. larvae spend 2–3 weeks in the water column before infecting their hosts and, therefore, mussels positioned at the top are exposed to higher numbers of planktonic larvae than mussels at the bottom. In contrast, infective trematode larvae spend less than 12 h in the water column and primarily infect mussels during low tide, which may explain higher prevalence and intensity of R. roscovita in mussels near the bottom of the oyster reef. Our results demonstrate that indirect effects leading to alterations of parasite-host interactions may be a more common but hitherto rarely considered impact of biological invasions.

Larval parasitic copepods affect early life history traits of a temperate clingfish.

Larval copepods are frequent parasites that infest fish larvae along the Chilean coast. Because these parasites develop on fish during the early development, when their bodies are fragile and in a recent stage, they can affect the fishes' early life history traits (ELHT). The goal of this study was to determine the effect of parasitic copepods on the ELHT of the larvae of the clingfish Gobiesox marmoratus (Teleostei: Gobiesocidae) using otolith microstructure analysis. Ichthyoplankton samples were collected during austral winter (July and August 2012), in the inner shelf waters off Valparaiso Bay, central Chile. A total of 95 non-parasitized larvae (NPL) and 95 parasitized (PL) with copepods were randomly selected for subsequent analyses. Parasitized larvae of G. marmoratus were larger than NPL. The right otolith tended to be larger than the left otolith in the fish larvae, but with a higher asymmetry in PL. The PL showed larger otoliths-at-size than the NPL, particularly in smaller larvae (< 8mm of standard length, SL). Nonetheless, parasitized larvae larger than 8mm SL showed the opposite trend that is smaller-at-size otoliths than NPL. The Gompertz models indicated that the asymptotic length of NPL doubled the length of PL; this suggests that parasitic copepods affect the maximum size attained by the PL. In conclusion, parasitic copepods negatively affect the ELHT of G. marmoratus larvae and the greater asymmetry can be attributed to parasitism.

Seasonal dynamics of parasite Lernanthropus kroyeri (van Beneden, 1851) on cultured sea bass Dicentrarchus labrax (Linnaeus, 1758) from the Adriatic Sea

Due to the great economic importance of sea bass Dicentrarchus labrax (Linnaeus, 1758) in Mediterranean mariculture, the aim of this study was to explore the seasonal dynamics of the copepod parasite Lernanthropus kroyeri (van Beneden, 1851) on the gills of cultured sea bass. This is the first study of L. kroyeri on cultured sea bass from the Adriatic Sea. Sea bass (N = 457) samples were taken monthly from October 2012 to October 2014, from the same floating net cage. A significant positive correlation (r = 0.24; P < 0.0001), was found between the sea bass length and the total number of parasites, and between the fish length and egg string length of L. kroyeri (r = 0.647; P < 0.0001). Prevalence of L. kroyeri ranged from 94.4% to 100%. Female parasites dominated the population throughout the research period (72.6%), followed by males (25%) and immature parasites (2.4%). Gravid females were most dominant during the summer season, with their numbers significantly dropping in the winter. Observed seasonal dynamics of L. kroyeri reproductive patterns suggest that the winter season may be the best period for control and treatment of the infection. Furthermore, this new data may provide a basis for the development of epidemiological models with a focus on preventive measures in order to improve health management of mariculture in the Adriatic Sea, as well as in the whole Mediterranean area.

Parasite acquisition by the invasive Chinese sleeper ( Perccottus glenii Dybowski, 1877) (Gobiiformes: Odontobutidae) in Latvia and Ukraine

The Perccottus glenii is one of the most invasive of European fish species. During August-September 2019, we examined Chinese sleeper from six waterbodies in Latvia and Ukraine for parasites. Seventeen parasite species were registered, including two ciliate species, one coccidia, one monogenean, one cestode, six trematodes, three nematodes, one acanthocephalan, one parasitic copepod, and one bivalve glochidia. Maximum species richness was registered in Ukraine, with eight species at Vylkove and three species at Lake Kartal. Numbers in Latvia were generally lower with three species at Ilgas and just one at Gailezers. The parasite fauna registered in Latvia was poor overall, the richest site being the University pond. Two non-native parasite species were registered, the monogenean Gyrodactylus perccotti and the copepod Neoergasilus japonicus. Gyrodactylus perccotti was observed in Lake Kartal and the Danube delta in Ukraine, but not in Latvia, while N. japonicus only occurred in the University Pond in Latvia. This is the first record of this species in Latvia. Low parasite acquisition by the Chinese sleeper in Latvia may be caused by the release of this fish from aquaria, which is commonly registered in the region. It is likely that such low parasite loads have contributed to the formation of stable populations and the subsequent increase in expansion.

New Natural Method for the Elimination of Salmon Farms Parasite Copepods

The observations carried out during the spring of 2014 on different Atlantic salmon (Salmo salar Linnaeus, 1758) sea farms around the island of Froya (Sor–Trondelag), Norway, served to lay the foundations for a totally natural and environmentally friendly method for removal salmon parasitic copepods known as sea lice. The method is based on two known data: the different stages of copepod larval development, some of which are free-living as part of plankton and the existence of marine invertebrates that feed on plankton and more specifically on zooplankton, that is, the animal part of the plankton that is where the copepod larvae are. If we combine these two facts, we obtain the main idea of the method: introducing marine invertebrate filter feeders in special devices (patent pending) inside the cages of the marine farms, it will only be necessary to let these invertebrates carry out their natural function of feeding based on copepod larvae, that is, when they are in their most vulnerable phase and in which they have not yet caused harm to the salmon. In this way, sea lice can be eliminated without the use of chemicals, medicines or methods that can cause unnecessary stress to salmon on sea farms.

Morphological analysis of Caligus elongatus von Nordmann, 1832 (Copepoda: Caligidae) from the rosy goatfish Parupeneus rubescens (Mullidae).

Copepods are a common component of ectoparasite assemblages of all kinds of fish, from all environments and ecosystems. In the present investigation, a total of 80 specimens of the rosy goatfish Parupeneus rubescens were randomly collected from the Arabian Gulf, and then transported to the laboratory in order to be dissected and examined for the presence of copepodid infections. Copepod parasites were recovered from the gills of the infected fish. One copepod species within the Caligidae family was identified and labeled as Caligus elongates von Nordmann, 1832. This copepod species examined using light and scanning electron microscopy to observe the most characteristic generic features. Morphological and morphometric characterizations revealed differences between the identified species and other related copepodid species. Therefore, the present study showed that the rosy goatfish is a new host for this Caligus species and added a new locality record for this infection.

Parasite development affect dispersal dynamics; infectivity, activity and energetic status in cohorts of salmon louse copepodids

The salmon louse, Lepeophtheirus salmonis, is a parasitic copepod infecting wild and farmed salmonid fishes in the northern hemisphere. It has a direct lifecycle with a planktonic dispersal phase and an infective copepodid stage preceding five host bound stages. Several models predicting the dispersal of this ecologically and economically important pathogen have been developed, but none include variability in capability to infect. Therefore, the effect of age and temperature on infectivity and lipid metabolism was investigated experimentally using seven synchronized cohorts of copepodids at 5, 10 and 15 °C. In newly molted copepodids infectivity initially increase and then decrease with senescence. Within the experimental temperature range, peak infectivity was higher and occurred earlier at higher temperatures. While degree-days may serve as a useful crude descriptor of developmental age, it did not allow accurate prediction of infectivity peak timing and magnitude unless temperature was included as a separate factor in the derived infectivity model. Senescence was reflected in lipid store depletion and a temperature dependent variability in membrane lipid composition was evident. Interestingly, copepodids developing at 5 °C had approximately 50% less storage lipids when they molted into the parasitic stage than those developing at 10 and 15 °C. The declines in infectivity and storage energy were mirrored in decreasing copepodid swimming activity. When incorporating the copepodid infectivity results from this study into salmon louse dispersal model parameterization, the predictions suggest that earlier models may have underestimated the seasonal differences in salmon louse infection risk.

Spiral valve parasites of blue and common thresher sharks as indicators of shark feeding behaviour and ecology.

This study documented the parasite faunas of the spiral valves of blue sharks Prionace glauca (L. 1758) and common thresher sharks Alopias vulpinus (Bonnaterre, 1788) caught in the California Current Large Marine Ecosystem (CCLME) north of the Mexican border. The spiral valves of 18 blue and 19 thresher sharks caught in the CCLME from 2009 to 2013 were examined for parasites. Seven parasite taxa were found in blue sharks and nine in threshers. The tetraphyllidean cestode Anthobothrium sp. (78% prevalence) was the most common parasite in blue sharks, and the phyllobothriid cestode Paraorygmatobothrium sp. (90% prevalence) was the most common in threshers. An adult nematode of the genus Piscicapillaria was found in threshers for the first time and may be a new species. Adult individuals of Hysterothylacium sp. were found in both shark species. The adult acanthocephalan Rhadinorhynchus cololabis and remains of the parasitic copepod Pennella sp. - both parasites of Pacific saury, Cololabis saira - were found in the intestines of threshers, indicating recent feeding on saury. This study paves the way for a more comprehensive examination, including more samples and a wider variety of shark species, to provide a greater understanding of shark feeding behaviour and possibly provide information on shark population biology.

Infection of the Pacific saury Cololabis saira (Brevoort, 1856) (Teleostei: Beloniformes: Scomberesocidae) by Pennella sp. (Copepoda: Siphonostomatoida: Pennellidae) south of the Subarctic Front

Abstract The Pacific saury (Cololabis saira) is a fish of commercial importance subject to unpredictable epidemics of infection by Pennella sp., a parasitic copepod. We analyzed the distribution of fish presenting with newly attached Pennella to determine the region and season in which Pennella first infect the fish. Pacific sauries migrate northward in the spring to spend the summer in the subarctic region, successively crossing the Subarctic Boundary (SAB) and the Subarctic Front (SAF). The fish then return to subtropical waters in the fall and overwinter there. Pacific sauries infected with Pennella were observed on both the north and south sides of the SAF from May to December. Newly attached Pennella, however, were observed mainly to the south of the SAF during the northward migration of the fish in May and June, and only to the south of the SAB during the southward migration in November and December. These results indicate that the intermediate host or hosts of Pennella inhabit the region south of the SAF, with infection of Pacific saury occurring during late fall and spring. Such information may assist in identifying the intermediate host(s).

The 2015-2016 El Niño increased infection parameters of copepods on Eastern Tropical Pacific dolphinfish populations.

The oceanographic conditions of the Pacific Ocean are largely modified by El Niño (EN), affecting several ecological processes. Parasites and other marine organisms respond to environmental variation, but the influence of the EN cycle on the seasonal variation of parasitic copepods has not been yet evaluated. We analysed the relation between infection parameters (prevalence and mean intensity) of the widespread parasitic copepods Caligus bonito and Charopinopsis quaternia in the dolphinfish Coryphaena hippurus and oceanography during the strong 2015-16 EN. Fish were collected from capture fisheries on the Ecuadorian coast (Tropical Eastern Pacific) over a 2-year period. Variations of sea surface temperature (SST), salinity, chlorophyll a (Chl-a), Oceanic Niño Index (ONI), total host length (TL) and monthly infection parameters of both copepod species were analysed using time series and cross-correlations. We used the generalised additive models for determine the relationship between environmental variables and infection parameters. The total body length of the ovigerous females and the length of the eggs of C. bonito were measured in both periods. Infection parameters of both C. bonito and Ch. quaternia showed seasonal and annual patterns associated with the variation of environmental variables examined (SST, salinity, Chl-a and ONI 1+2). Infection parameters of both copepod species were significantly correlated with ONI 1+2, SST, TL and Chl-a throughout the GAMLSS model, and the explained deviance contribution ranged from 16%-36%. Our results suggest than an anomaly higher than +0.5°C triggers a risen in infection parameters of both parasitic copepods. This risen could be related to increases in egg length, female numbers and the total length of the ovigerous females in EN period. This study provides the first evidence showing that tropical parasitic copepods are sensitive to the influence of EN event, especially from SST variations. The observed behaviour of parasitic copepods likely affects the host populations and structure of the marine ecosystem at different scales.

Light and scanning electron microscopic studies of Lepeophtheirus salmonis (Siphonostomatoida: Caligidae) infecting the rosy goatfish Parupeneus rubescens

Parasites, particularly crustaceans, are considered as an important limiting factor in the development of intensified fish culture. The parasitic copepod of the Arabian Gulf fish is poorly known. So, the current investigation aimed to record the caligid species infecting the rosy goatfish Parupeneus rubescens in the Arabian Gulf. One copepod species was identified belonged to family Caligidae and labeled as Lepeophtheirus salmonis Krøyer 1837 depends mainly on its morphological, morphometric, and ultrastructural characteristics. It is characterized by lacking lunules, the anterior margin of the cephalothorax is not folded, three-segmented exopod of the fourth leg and longer than the protopod, leg 4 with the middle terminal claw as long as the inner one, accessory processes on terminal elements II and III of the exopod of the first leg, a genital complex distinctly wider than being long, and a relatively short abdomen. Therefore, the present study demonstrated that the rosy goatfish represents a new host for Lepeophtheirus species and added locality records for this infection.

High Prevalence of the Copepod Salmincola californiensis in Steelhead Trout in Lake Ontario Following its Recent Invasion

Salmincola californiensis (Dana, 1853) (Subclass Copepoda: Family Lernaeopodidae) is known to parasitize salmonids of the genus Oncorhynchus including Oncorhynchus mykiss (rainbow trout), Oncorhynchus tshawytscha (chinook salmon), and Oncorhynchus kisutch (coho salmon). These 3 salmonids have been introduced to the Great Lakes intermittently since the mid-1800s. As we demonstrate here, the introduction of these salmonids to the Great Lakes was followed, at some point, by the introduction of their parasitic gill copepod, S. californiensis. Given anecdotal accounts of S. californiensis in introduced salmonids in Lake Ontario since 2012, we chose to conduct a survey to formally document the occurrence of this introduced species. Our survey took place during spring, summer, and fall of 2018 and during spring of 2019 at the south-eastern side of Lake Ontario. Prevalence of S. californiensis was 69, with a mean intensity of 2.7 in 61 rainbow trout examined in 2018. In 2019, prevalence of S. californiensis was 71, with a mean intensity of 3.6 in 59 rainbow trout examined. The prevalence of S. californiensis was 39, with a mean intensity of 1.6 in 223 chinook salmon examined in 2018. No specimens of S. californiensis were found in the 100 coho salmon examined in 2018. The prevalence of S. californiensis in rainbow trout is of great concern considering that it is double that found in rainbow trout in the native range (69 [in 2018] and 71 [in 2019] vs. 35). This is the first formal documentation of the invasion of S. californiensis in Lake Ontario. Future fisheries management decisions in Lake Ontario and its tributaries should take into account these data.

Parasitic copepods of the family Lernanthropidae Kabata, 1979 (Copepoda: Siphonostomatoida) from Australian fishes, with descriptions of seven new species.

The total number of species of Lernanthropidae previously recorded from Australian waters is 15 (i.e., one species each of Aethon Krøyer, 1837, Lernanthropodes Bere, 1936, and Lernanthropsis Do, in Ho Do, 1985; 10 species of Lernanthropus de Blainville, 1822; and two species of Sagum Wilson, 1913), and all of these records are reviewed. We report here the presence of three species of Aethon. One species, A. garricki Hewitt, 1968, is reported from Australian waters for the first time and a new species, A. bicamera sp. nov., is described from the latrid, Latris lineatus (Forster, 1801) caught off South Australia. The genus Lernanthropodes is represented by a single species, L. trachinoti Pillai, 1962. We recognize Chauvanium Kazachenko, Kovaleva, Nguyen Ngo, 2017 as a subjective synonym of Lernanthropodes and transfer its type and only species C. chauvani Kazachenko, Kovaleva, Nguyen Ngo, 2017 which becomes Lernanthropodes chauvani (Kazachenko, Kovaleva, Nguyen Ngo, 2017) n. comb. Lernanthropsis mugilii (Shishido, 1898) is reported here from Mugil cephalus Linnaeus, 1758 sampled in Queensland and in New South Wales. The genus Lernanthropus is the most species rich and we report the presence of 20 nominal species on Australian marine fishes. This total includes six new species: L. alepicolus sp. nov. from Alepes apercna Grant, 1987, L. elegans sp. nov. from Atractoscion aequidens (Cuvier, 1830), L. gnathanodontus sp. nov. from Gnathanodon speciosus (Forsskål, 1775), L. paracruciatus sp. nov. from Protonibea diacanthus (Lacepède, 1802), L. pemphericola sp. nov. from Pempheris compressa (White, 1790), and L. selenotoca sp. nov. from Selenotoca multifasciata (Richardson, 1846). In addition, we report the presence of another four species in Australian waters for the first time: L. abitocephalus Tripathi, 1962, L. cadenati Delamare Deboutteville Nuñes-Ruivo, 1954, L. microlamini Hewitt, 1968, and L. pomadasysis Rangnekar Murti, 1961. After reexamination of the types of L. paenulatus Wilson, 1922 held in the USNM, we relegate this species to subjective synonymy with L. seriolii Shishido, 1898. Previous records of L. paenulatus from Australian Seriola species should be reassigned to L. seriolii. Lernanthropus ecclesi Kensley Grindley, 1973 is recognized as a junior subjective synonym of L. micropterygis Richiardi, 1884, and L. delamarei Marques, 1960, which is based on the male only, is tentatively considered to be a junior subjective synonym of L. micropterygis. Males are described for the first time for three species; L. breviculus Kabata, 1979, L. microlamini and L. mollis Kabata, 1979. A member of the genus Mitrapus Song Chen, 1976, M. oblongus (Pillai, 1964), is reported from Australia for the first time, on Herklotsichthys castelnaui (Ogilby, 1897) caught off Queensland and New South Wales. Finally, two species of Sagum were previously known from Australia and here we add three more. Two of the newly reported species were originally described as species of Lernanthropus but we formally transfer them here to Sagum as S. lativentris (Heller, 1865) n. comb. and S. sanguineus (Song, in Song Chen, 1976) n. comb. The males of S. lativentris and S. vespertilio Kabata, 1979 are described for the first time. A key to the females of the 31 species of lernanthropids found in Australian waters is provided.

A Study of Parasitic Copepod Infesting Two Freshwater Fish Populations (Cyprinus carpio and Abramis brama) from Beni-Haroun Dam (Mila) North-East of Algeria

Copepods are one of the main fish ectoparasites, commonly known among the parasitism world, due either to their special adaptive capacity or to induce stress in aquatic organisms, as well as the parasitism result is overall a physiological rate affecting the survival of host. This study was, therefore, aimed to investigate the ectoparasite copepods, infesting 277 fishes including 135 of Cyprinus carpio (Linnaeus, 1758) and 142 of Abramis brama (Linnaeus,1758), collected from Beni-Haroun dam (Mila, northeast Algeria). The fishes were subjected to some morphometric measurements and gill dissections and the harvested parasites were afterwards stored and identified. The parasitic indices were determined to examine the effect of size, sex, season and microhabitat on the parasitic infestation by using χ2 test. The gill examination of individuals of the two host fishes led to harvest 135 copepods, including 127 individuals from Cyprinus carpio belonging to five species (Ergasilus sieboldi, Ergasilus briani, Neoergasilus japonicus, Neoergasilus longispinosis and Lernaea cyprinacae) and 8 individuals from Abramis brama belonging to the two species: Ergasilus sieboldi and Ergasilus briani, and hence Cyprinus carpio is the most infested species than Abramis brama. This study also revealed that the parasitic index values were high in C. carpio (P=53.00%; A=3.7; I=6.93) compared to A. brama (P=12,0.5%, A=0.12, I=1.00) during autumn, since no effect on infestation was noticed during winter. The statistical analysis has revealed the effect of season on parasitic copepod infestation in the two fish species (χ2Obs =30,959 &gt; χ20.05 = 7,815, ddl =3), Since there was no effect due to the microhabitat and sex.

A New Species of Rhinergasilus Boeger et Thatcher, 1988 (Copepoda: Ergasilidae) from Gills of Astyanax fasciatus (Cuvier, 1819) (Actinopterygii: Characidae)

To describe a new species of a parasitic copepod, Rhinergasilus digitus n. sp. (Cyclopoida, Ergasilidae), collected from the gills of the red-tailed lambari Astyanax fasciatus (Characiformes, Characidae) in two tributaries of the Jurumirim Reservoir (Upper Paranapanema River), São Paulo State, Brazil: Ribeirão dos Veados and Paranapanema River. Fish were collected using multi-panel gills nets. The gill of each fish was washed and examined in a stereo microscope for copepods. The copepods found were stored in 70% ethanol, cleared in lactic acid, and mounted in Hoyer's medium. Drawings were made with the aid of a Leica microscope DMLS equipped with a drawing tube. The new species differs from its congeneric species, Rhinergasilus piranhus (type-species), in having comparatively biggest body size (body length: 535-598µm in the new species vs. 237-282µm in R. piranhus); second antennary segment armed with a minute sensillum near middle of inner margin and a row of spinules on outer margin; third exopodal segment of leg 1 with digitiform process; interpodal plates two and three both ornamented with spinules along posterior margin; leg 5 reduced and represented by two unequal setae. Based on the morphological differences described above, we erected a new species of Rhinergasilus. Rhinergasilus digitus n. sp. is the second ergasilid described from A. fasciatus, as well as it represents the first report of this genus in a characid fish.

Ergasilus sp. (Copepoda: Ergasilidae), parasito de Genidens barbus (Lacepède, 1803) provenientes do Canal de Bertioga, São Paulo

RESUMO Espécies de Ergasilus Nordman, 1832 são copépodos parasitos encontrados em todo o mundo em ambientes aquáticos, e são considerados importantes causadores de doenças em piscicultura. As fêmeas destes crustáceos são encontradas parasitando os peixes, uma vez que os machos possuem vida livre no zooplâncton. Um de seus importantes hospedeiros, Genidens barbus, ocorre na costa Leste do Brasil, em águas costeiras, estuários e no curso inferior de rios, desde o Rio de Janeiro até o Rio da Prata, sendo considerado o bagre marinho mais abundante nas regiões estuarinas do Sudeste/Sul do Brasil. A existência de espécies desconhecidas de parasitos ainda é muito grande, por isso há a necessidade de se conhecer mais à respeito da biodiversidade parasitária existente para servir de auxílio para as espécies que base para novas descrições e até mesmo re-descrições. Com isso, o presente estudo teve o objetivo de estudar a biodiversidade de ectoparasitos de G. barbus coletados no Canal de Bertioga – SP. Foram coletados sete espécimes deste hospedeiro por um pescador local e levados até o laboratório de Ictioparasitologia na cidade de Bauru, onde foram necropsiados individualmente. No momento da necropsia as brânquias foram analisadas a procura de ectoparasitos. Este órgão foi passado pela peneira com abertura de 75µm e lavado em água corrente e o conteúdo foi analisado em estereomicroscópio à procura de parasitos. Foram encontrados um total de 111 espécimes de copépodas parasitando as brânquias, sendo 40 espécimes pertencentes a espécie Ergasilus sp. (Copepoda: Ergasilidae) e os outros 71 espécimes ainda não foram identificados. A espécie analisada no presente estudo apresentou intensidade média = 13,3 ± 2,44; abundância média = 5,71 ± 0,82 e prevalência = 42,9%. Desse modo, o estudo realizado com a biodiversidade parasitária tem se apresentado como um importante recurso para o conhecimento mais especifico de parasitos de peixes ainda não analisados, como é o caso das diversas espécies encontradas no Canal de Bertioga, um dos importantes estuários brasileiros.&#x0D; PALAVRAS-CHAVE: Ergasilus, Biodiversidade, Canal de Bertioga.

Hiện trạng nhiễm ký sinh trùng ở cá tra (Pangasianodon hypophthalmus) giai đoạn ương giống

The study was conducted to determine the current status of parasitic infection in three nursing stages (larval, fry and fingerling stages) of striped catfish (Pangasianodon hypophthalmus). A total of 857 fish (302 samples of larval stage, 218 samples of fry stage and 337 samples of fingerling stage) were sampled from 20 nursery ponds (9 ponds in rainy season and 11 ponds in dry season). The parasitic composition and the infection rate from different nursing stage of fish were examined. Results showed that nine parasite genera (Cryptobia, Trichodina, Balantidium, Apiosoma, Epistylis, Myxobolus, Henneguya, Dactylogyrus, and Gyrodactylus) were found in striped catfish at nursing stage. Besides, cysts of some parasites were identified as Myxozoans, metacercariae of trematodes, larval nematodes and parasitic copepods. Parasitic infection rate was higher in the dry season than the rainy season. In which, the infection rate in dry season was observed at the rate of 56.6%-73.3% in larvae, 50%-100% in fry, 73%-85.7% in fingerlings. The infection rate in the rainy season was observed at the rate of 15%-57.3% in larvae, 40%-100% in fry, 25%-90.3% in fingerlings. In particular, Trichodina, Apiosoma, Epistylis, Myxozoa, Myxobolus, Henneguya spores are commonly found on skin and gills of fish in both dry and rainy seasons. The trend in prevalence and species composition of parasites observed in this study may reflect the specific time of nursing stage to apply interventions in order to reduce the pathogenic impact of the parasites.

New species of Acanthochondria Oakley, 1930 and Chondracanthus Delaroche, 1811 (Copepoda: Cyclopoida: Chondracanthidae) parasitizing marine fishes from Indian waters

Abstract This paper describes two new species of parasitic copepods of the family Chondracanthidae H. Milne Edwards, 1840. Acanthochondria krishnai sp. n. is described from Dollfus' stargrazer, Uranoscopus guttatus Cuvier, collected from Muttom and Colachel, Tamil Nadu, and Chondracanthus kabatai sp. n. from Silvery john dory, Zenopsis conchifer Lowe, collected from Neendakara, Quilon, Kerala, both along the southwest coast of India. Both the species are described and illustrated based on the fresh female and male specimens collected from India. Both the species are the first Indian representative of the respective genera. The checklist of Indian species of the family Chondracanthidae is also presented.