Parasitic Isopods Research Articles

Morphological and Molecular Study of the Fish Parasitic Crustaceans Cymothoa indica and Mothocya collettei (Isopoda: Cymothoidae), with New Distribution Records

Cymothoidae are parasitic isopods that infest fishes inhabiting marine, brackish, and fresh-water environments. The systematics, distribution, and host specificity of cymothoids is often unknown. In this study, morphological observations and molecular analysis using the COI and 16S rRNA genes were conducted on a juvenile individual of Cymothoa indica infesting the wide-banded hardyhead silverside, Atherinomorus lacunosus, and an ovigerous female of Mothocya collettei infesting the hound needlefish, Tylosurus crocodilus, both collected from Okinawa Island, Japan. This is the first time that these two species of cymothoid have been collected in the Ryukyu Islands, and the juvenile C. indica in particular represents a new northern range limit for its species. That specimen was identified using molecular analysis and showed almost identical morphology to previously reported juveniles, but it differed in the numbers of robust setae on pereopods 6 and 7. The ovigerous female of M. collettei showed a high morphological similarity to M. collettei but had some morphological traits consistent with Mothocya affinis. DNA analysis indicated that these two nominal species of Mothocya are very closely related, and morphological and molecular studies using larger populations of both are needed.

The use of fish parasitic isopods as element accumulation indicators in marine pollution monitoring

Marine ecosystems are continuously under threat due to pollutants, which endanger marine biodiversity. The present study determines the potential use of the parasitic isopod, Cinusa tetrodontis Schjödte et Meinert, 1884, together with its fish host, Amblyrhynchotes honckenii (Bloch) for marine bioaccumulation monitoring. The concentrations of As, Cd, Cu, Mn, Ni, Pb, Se, and Zn were determined in muscle and liver tissues of infested and uninfested fish, and male and female parasites on the South African temperate south coast. The concentrations of Cu and Ni in C. tetrodontis differed significantly between two sampling sites, a near-pristine (Breede River Estuary, Witsand) and a more polluted site (harbour area in Mossel Bay). Mossel Bay isopods had higher concentrations of Ni, while Witsand isopods had higher concentrations of Cu. In contrast to fish hosts, parasitic isopods accumulated significantly higher levels of all elements except Cd. Most significant relationships between elements accumulated by C. tetrodontis and an increase of elements in fish tissues were seen in liver, rather than muscle tissue samples. Specimens of C. tetrodontis can be defined as good bioindicators for elements such as As, Cu, Mn, Ni, Pb, Se, and Zn, as they possess high bioaccumulation capabilities. This study addresses one of several future directions needed within environmental parasitology and highlights the importance of studying and utilising this host-ectoparasite model system.

Checklist of parasitic isopods from Brazil: Bopyroidea and Cryptoniscoidea (Isopoda: Cymothoida: Epicaridea).

All species of Brazilian parasitic isopods belonging to Epicaridea (Bopyroidea and Cryptoniscoidea) known to date, including references and distribution information, are listed. The list comprises 37 valid species, 18 of which are endemic to the country, 17 are also recorded from other countries in the Americas, and only two species are distributed outside of the American continent as well. Synonym list, known hosts and distribution are given for each of the species, along with taxonomic and ecological remarks when relevant.

Prevalence of parasitic isopods (Cymothoidae and Gnathiidae) on Actinopterygii fishes from the Alexandria coast off the Mediterranean Sea, Egypt

Prevalence of parasitic isopods (Cymothoidae and Gnathiidae) on Actinopterygii fishes from the Alexandria coast off the Mediterranean Sea, Egypt

A new species of parasitic isopod (Bopyroidea: Ionidae) infesting burrowing shrimp (Axiidea: Callianassidae) in the tropical eastern Pacific.

A new species of parasitic isopod in the genus Ione Latreille, 1818, infesting the branchial chamber of the intertidal burrowing shrimp Neotrypaea tabogensis (Sakai, 2005) is described on the basis of material collected on the Pacific coast of Costa Rica. Diagnostic features of the new species include: (1) body shape of female asymmetrical with slight left distortion, pereon segments distinct; (2) head of female not fused with first pereomere, posterior margin nearly straight; (3) antenna of female composed of five articles; (4) posterior lamella of barbula of female with two tapered lobes on each side; (5) body of male elongated, clearly segmented dorsally; (6) head of male completely separated from the first pereomere; and (7) maxillipeds absent in male. This is the seventh valid species in the genus Ione and the first record of this genus from the tropical eastern Pacific. A key for identification of species of Ione is also provided.

Quatrefoil light traps for free-swimming stages of cymothoid parasitic isopods and seasonal variation in their species compositions in the Seto Inland Sea, Japan.

Cymothoid parasitic isopods infest a wide range of fish of different taxa living in marine, brackish, and freshwater environments. Most research on the reproductive season of Cymothoidae has been done by collecting or monitoring host fish afflicted with cymothoid parasites. However, collecting ecological data on cymothoid species that infest non-commercial or endangered fishes is complex and challenging. We used a quatrefoil light trap to investigate the seasonal change in species composition of cymothoid free-swimming stages in the Seto Inland Sea, Japan. We also collected preliminary data for efficient light-trap sampling and showed its effectiveness in cymothoid-related research. From October 2020 to December 2021, 613 cymothoid free-swimming stages were sampled monthly. All obtained individuals were identified as Mothocya parvostis (596), Ceratothoa verrucosa (12), and Ceratothoa carinata (5) by DNA barcoding using cytochrome c oxidase subunit I and 16S rRNA gene sequences. Based on the number of M. parvostis mancae collected each month, M. parvostis was anticipated to reproduce from June to December, with two reproduction peaks each year, and C. verrucosa and C. carinata were expected to reproduce in June, July, and September, and September and October, respectively. In addition, free-swimming juveniles were captured, presumably after they had left their optional intermediate hosts. Furthermore, the most effective time to harvest cymothoids with light traps may be during high tide on the night of the new moon. This study serves as a methodological framework for future research on cymothoids using light traps.

Nomenclatural and taxonomic changes in parasitic isopods (Isopoda: Epicaridea), including two new families and note on the questionable association between monogeneans and bopyrids

Several long-standing taxonomic and nomenclatural problems in bopyroid and cryptoniscoid isopods are addressed. Within Bopyroidea we propose five new synonomies, three new combinations, a correction of the spelling of one species and a replacement name for another. In addition, the likely erroneous conclusion that a monogenean is an associate of bopyrids is discussed. Within Cryptoniscoidea, we determined the familial placement of three genera that were previously designated as incertae sedis (Capitoniscus Bourdon, 1972 and Carocryptus Schultz, 1977) or of doubtful affiliation (Cumoechus Hansen, 1916). In total, five species of cryptoniscoids are placed into two new families (Capitoniscidae n. fam. and Cumoechidae n. fam.), each containing at least one species known from both female and cryptoniscus larvae/paedomorphic male stages. Finally, the status of two cryptoniscoid genera is addressed: Gorgoniscus Grygier, 1981 is placed in Hemioniscidae, and Leponiscus Giard, 1887, is synonymized with Hemioniscus Buccholz, 1866.

Cryptic diversity in endoparasitic isopods (Bopyroidea: Entoniscidae) from mud crabs (Panopeidae) along the Atlantic coast of North America, with the description of a new genus and new species as revealed by molecular and larval characters: the long and the short of it

AbstractAlthough intertidal crabs from the western Atlantic coast are relatively well studied for some parasite fauna, their parasitic isopods are poorly known. We document two endoparasitic entoniscids (Cancrion carolinusPearse & Walker, 1939 and Cryptocancrion brevibrachiumn. gen., n. sp.) from mud (Brachyura: Panopeidae) and stone (Brachyura: Menippidae) crabs based on molecular and morphological data, including descriptions of their epicaridium larvae. Although these species cannot be distinguished based on adult female characters, molecular data and larval and male morphologies show that two species are present, sometimes sympatrically. The only other species of CancrionGiard & Bonnier, 1887 from the Atlantic coast of North America is Cancrion needleriPearse & Walker, 1939, described from adult specimens parasitizing Dyspanopeus sayi (Smith, 1869) from Prince Edward Island, Canada. Larvae of this species were never described and we consider it a species inquirenda. Cryptocancrion brevibrachiumn. gen., n. sp. is documented to have epicaridium larvae with a “short-armed” morphology (sixth pereopod subequal in length to pereopods 1–5), and the adults parasitize at least three mud crabs: D. sayi, Panopeus herbstiiH. Milne Edwards, 1834, and Rhithropanopeus harrisii (Gould, 1841). By contrast, Cancrion carolinus (originally described from P. herbstii collected in Beaufort, NC, USA) has epicaridium larvae with a “long-armed” morphology (sixth pereopod approximately twice the length of pereopods 1–5) and is found in at least four host species: Eurypanopeus depressus (Smith, 1869), P. herbstii, and R. harrisii and the stone crab Menippe mercenaria (Say, 1818). We describe C. brevibrachiumn. gen., n. sp. and redescribe C. carolinus based on type material and fresh specimens. The cryptic nature of these entoniscids indicates that examination of epicaridium larvae and/or molecular data are needed to properly identify species.

Morphological Description and Molecular Characterisation of Glyptothoa gen. nov., a Fish Parasitic Deep-sea Cymothoid (Crustacea: Isopoda) from the Indian Ocean, with Four Species, Including One New Species.

Glyptothoa sagara gen. and sp. nov. is described from the host fish Glyptophidium macropus Alcock, 1894 (Ophidiidae), at depths 300 to 650 metres from the southwest coast of India. The mitochondrial cytochrome c oxidase subunit I (COI) gene of the species was sequenced and compared with other closely related branchial cymothoid genera. Both morphological and molecular data corroborate the inclusion of this parasitic isopod as a new genus, and we describe Glyptothoa sagara gen. and sp. nov. The following combinations of characters characterise the genus: cephalon immersed in pereonite 1; dorsum vaulted; all coxae visible in dorsal view; coxae shorter than or as long as pereonites; pereonites 4-7 slightly decrease in width towards one side, slightly asymmetrical, lateral margins slightly constricted, in hunched side; relatively wide pleon, with large lateral gaps between pleonites; antennula narrowly separated by rostrum, slender, shorter than antenna; antenna with 13 articles, buccal cone obscuring antennal bases; brood pouch arising from coxae 1-4, 6; oostegite 1 bilobed; pleopods rami all simple, without proximomedial lamellar lobe, without folds or thickened ridges. The adult life stages, such as females (ovigerous and non-ovigerous), males and transitional stage of the new species are described. The species is currently known only from the type locality and the type host. The ecological remarks of the newly described taxon are also provided. The following species are transferred from Elthusa Schioedte and Meinert, 1884: Glyptothoa myripristae (Bruce, 1990) comb. nov., Glyptothoa propinqua (Richardson, 1904) comb. nov. and Glyptothoa caudata (Schioedte and Meinert, 1884) comb. nov.

Reproductive behaviour of the branchial ectoparasite Bopyrus crangorum (Isopoda: Bopyridae) following ecdysis of the host Palaemon serrifer (Caridea: Palaemonidae)

Abstract The reproduction of bopyrid isopod parasites is thought to occur immediately following host ecdysis, but direct observations supporting this hypothesis are limited. The aim of this study was to describe the reproductive behaviour of the bopyrid isopod Bopyrus crangorum relative to host ecdysis based on video recordings. Several hours after host ecdysis, biphasic moulting of female parasites was observed. The cuticle of the posterior body was shed before that of the anterior body at an interval of 1 h. Two hours after female moulting, the male repeatedly moved from its initial position between the female pleopods and stopped at the anterior end of the fifth oostegite, immediately above the gonopore. To our knowledge, this repeated visiting behaviour by males has not been previously observed in bopyrid isopods. Oviposition through the female gonopore occurred 33 min later. The male-removal experiment showed that females with their males removed after visits to the gonopore oviposited eggs, whereas females with their males removed before visits did not. We propose that repeated visits by males to the gonopore are attempts to inseminate the female. We hypothesised that sperm are released onto the external surface of each gonopore and that the eggs are fertilised as they pass through the opening, which would explain the synchronous development of fertilised eggs inside the marsupium. The present study provides new information on the life history of bopyrid isopods, which allows for a better understanding of the host–parasite relationship.

New host–parasite associations of Cymothoidae (Crustacea, Isopoda) infesting elasmobranch fishes in Tunisian waters

Between 2015 and 2020, 2 092 specimens of cartilaginous fishes (Chondrichthyes: Elasmobranchii) belonging to eight species and five genera were sampled along the Tunisian coast and examined for their cymothoid parasites, Among the eight examined elasmobranch species, only three were infested, Five parasite species were identified: Anilocra physodes, Emetha audouini, Ceratothoa oestroides, C. parallela and Nerocila orbignyi, These parasites presented three maturation stages: ovigerous females of A.physodes and E. audouini, adult non-ovigerous females of N. orbignyi, and juvenile females of C. oestroides and C. parallela, Most of these parasitic isopods were found on a single host species except for the two Ceratothoa species. We report new host-parasite associations, including the presence of A. physodes and E.audouini on smooth-hound Mustelus mustelus, the occurrence of C. oestroides and N. orbignyi on cartilaginous fish species, and the presence of C. parallela on black smooth-hound Mustelus punctulatus and M. mustelus. Parasitological indices and the seasonal variation in prevalence of the collected cymothoids, as well as parasitic species richness, are presented.

Identification and observations of parasitic isopod larvae (Isopoda: Epicaridea) from the northeastern Pacific: pelagic distribution and association with copepod intermediate hosts

Abstract Zooplankton samples from the northeastern Pacific, USA were analyzed to identify and determine the abundance and distribution of parasitic isopod larvae and copepod hosts. Vertically stratified samples were collected at stations spanning the continental shelf off Oregon, USA. Two species of epicarideans were identified: Hemioniscus balaniBuchholz, 1866 (endoparasite of barnacles) and Argeia pugettensisDana, 1853 (ectoparasite of shrimps). Cryptoniscus larvae of these species can be distinguished based on the antennae (four basal and five flagellar articles in H. balani, four basal and four flagellar articles in A. pugettensis), tooth-like structures on the antennules and coxal teeth (present in H. balani, lacking in A. pugettensis), and pereopods (1, 2 gnathopodal and 5, 6 ambulatory in H. balani, all gnathopodal in A. pugettensis). Epicaridean larvae were rare in zooplankton samples with concentrations up to 10 m–3. Larvae were often found within 10 km of shore, with highest concentrations below the Ekman layer at 20–50 m depth near the bottom and between the 8 and 10°C isotherms. Likely as a result of dislodgment, only 26 copepods with epicaridium or microniscus larvae attached were confirmed. Larvae were mostly (78%) found attached to two species of Acartia, suggesting they were the preferred host, but five other genera of copepods were documented as hosts. The concentration of copepods and larvae exhibited a significant positive correlation when the analysis was limited to stations where both larvae and copepods were caught. The distribution of host copepods was significantly shallower than epicaridean larvae and generally closer to shore. The planktonic phase of the life cycle of epicarideans remains a black box for most of the +860 known species. Future work should include molecular data to link their larval and adult life cycle stages and connect the parasites with their intermediate hosts.

Overlapping and partitioning of niche among different life stages of the parasitic isopod Cymothoa indica in the host Glossoglobius guiris collected from the Chilika lagoon, India.

The present paper reports the site of attachment preference, overlapping and partitioning of niche among different life stages of parasitic isopod Cymothoa indica Schiöedte and Meinert, 1884 in the Gobiidae fish Glossogobius giuris (Hamilton 1822) collected from the Chilika lagoon, India. Out of 2113 host fishes, 176 were found to be infected by the parasites. Out of the 233 different life stages of the parasites examined, 89 were female, 104 were male, and the rests were juveniles. 100% of the females, 84.6% of the male and 72.5% of the juveniles were found to be attached to the buccal cavity, while the rest of the males and juveniles were attached to the branchial cavity. In most cases, there was niche overlapping, leading to competition for the resources. Females preferred more specialized niches as compared to males and juveniles. In a few instances, there is niche partitioning, as shown by the male and juveniles. There is a negative correlation between the number of parasites found in the body of the fishes and the weight of the host fishes. This manuscript also provides a brief description of the different life stages of this parasite in the above-mentioned host collected from the same lagoon.

The Meta-Analysis of Aminoacids and Minerals in the Fish Lisa parsia (Hamilton 1822) Parasitized with the Isopod, Nerolica indica

The aim of the present investigation was to study the effect of parasite infestation of the crustacean isopod, Norileca indica in the fish, Liza parsia (Goldspot Mullet). The crustacean parasitic isopods affect the economically important fishes. Due to the infection, the host loses its weight, growth, and physiological inactivity, which eventually leads to death. Important biochemical parameters such as aminoacid profile, elements, and minerals were estimated. Arginine, isoleucine, methionine, leucine, and valine were found to be reduced by 0.5, 0.8, 0.6, and 0.7% in the parasitized fish. Significant reductions in lysine and phenylalanine by 1.2 and 1.6% respectively were noticed in the parasitized fish. No change in the tryptophan level was noticed. The aspartic acid and glutamine were also significantly reduced by 1.4 and 2.3 Wt/% respectively. The minerals like phosphorous and iron have increased significantly by 7.27 and 0.03 mg/100 gm respectively in parasitized fishes, whereas the minerals such as calcium, potassium, sodium and magnesium levels were found to be reduced in the parasitized fishes. No significant difference in manganese was observed. The amino acid and mineral content alterations observed in the infested fishes are reflecting, anaemia, tissue damage and disturbances in physiological homeostasis of fish physiology and biochemistry. Parasite infestation leads to the poor quality and flavour of the fish.

Occurrence of infestation with the isopod, Alitropus typus M. Edwards (Crustacea: Flabellifera: Aegidae) on commercially important freshwater fishes of Kerala, India.

Rapidly rising temperatures and increasing organic load in the inland and coastal waters has led to a significant increase in parasite population. The isopod Alitropus typus infestation on fish in these waters have become more frequent, causing mortalities in both wild and cultured fishes. The present study was aimed to investigate the infestation on different fish hosts, mean intensity, prevalence, environmental influences on the parasite abundance and the histopathological changes it causes in the host. A total of 219 isopod specimens were collected from 149 infested fishes in two districts of Kerala, India. Among the different fish hosts, Channa striata was found to be the most susceptible, followed by Catla catla, Cyprinus carpio, and Wallago attu, with 81%, 10%, 7%, and 2% occurrence, respectively. The prevalence and mean intensity of infestation were found to be 69.8%, 44.4%, 68.2%, 62.5% and 1.33, 4.25, 1.26, 1.80 in C. striata, W. attu, C. catla, and C. carpio, respectively. The parasite abundance was directly influenced by temperature. The histopathology of affected gill tissues showed epithelial lifting, rupture of secondary gill filaments, vacuole formation and hemocytic infiltration. The findings indicated that the isopod parasite, A. typus had a negative impact on fish health and appearance, causing economic losses to the small scale farmers/fishermen. This is the first reported record of the infestation of isopod parasite, A. typus on the Indian major carp C. catla and C. carpio from India.

Redescription of the fish parasite Nerocila serra Schioedte and Meinert, 1881 (Isopoda: Cymothoidae) from India, with a lectotype designation, and Nerocila pulicatensis Jayadev Babu and Sanjeeva Raj, 1984 placed into synonymy

ABSTRACT The parasitic isopod Nerocila serra Schioedte and Meinert, 1881 is redescribed based on a gravid female lectotype (here designated) from the Swedish Museum of Natural History and additional material from Indian waters. Nerocila pulicatensis Jayadev Babu and Sanjeeva Raj, 1984 is here placed into synonymy with N. serra. Ovigerous females of N. serra can be distinguished from their congeners by the coxae and postero-lateral angles of all pereonites narrowly produced; coxae 5–7 pointed with broad processes, longer than their respective segment; pereopod 3 with a single distal spine on the propodus; and uropodal endopod longer and narrower than exopod, with a shallower notch on the medial margin and small serrations on the lateral margin.

First report of parasitic isopod Nerocila orbignyi (Cymothoidae) from India with its molecular characterization.

The present report provides the first material evidence ofNerocila orbignyi(Guérin-Méneville, 1832) collected from two different landing centres of the Chilika lagoon, thus claiming the first report of this parasite from India. One of the specimens was recorded from the host fish speciesPlotosus caniusHamilton 1822, constituting the first host record for this isopod. A key for the identification ofN. orbignyi among its congeners is also provided.Molecular characterization of Cytochrome C Oxidase I (COI) gene ofN. orbignyiwas based on one specimen submitted for the first time to the NCBI database. This parasite is differentiated from the other available sequences of its related congeners retrieved from the NCBI and BOLD database by 26-34% in the Kimura 2 Parameter (K2P) distance and belongs to a separate cluster in Maximum likelihood (ML) tree analysis.

Infection of the parasitic isopods on commercial fishes of the northern part of the east coast of India.

The online version contains supplementary material available at 10.1007/s12639-021-01463-1.

New host findings of two parasitic isopods (Flabellifera: Cymothoidae) found on some fish caught in the Dardanelles Strait (Çanakkale, Turkey)

Seven cymothoid species are identified in parasitological studies conducted in the Dardanelles Strait between May 2018- May 2020. The Cymothoids identified are as follows: Mothocya epimerica Costa, 1851, Nerocila bivittata (Risso, 1816), Anilocra frontalis H. Milne Edwards, 1840, Ceratothoa oestroides (Risso, 1826), Ceratothoa parallela (Otto, 1828), Ceratothoa italica Schiödte & Meinert, 1883, Emetha audouini (H. Milne Edwards, 1840). A. frontalis and C. italica are found for the first time from Sciaena umbra Linnaeus, 1758 and Boops boops (Linnaeus, 1758) respectively. Although several reports of these parasites have been given from Turkey, the morphological characters of three species have not been given. The drawings, descriptions of the mouthparts, pereopods, and pleopods of N. bivittata, A. frontalis, C. italica are given in this study.

Truly a hyperparasite, or simply an epibiont on a parasite? The case of Cyclocotyla bellones (Monogenea, Diclidophoridae).

Cyclocotyla bellones Otto, 1823 (Monogenea, Diclidophoridae) is one of the few monogenean species reported as hyperparasitic: the worms dwell on cymothoid isopods, themselves parasites of the buccal cavity of fishes. We present here observations based on newly collected monogenean specimens from Ceratothoa parallela (Otto, 1828), an isopod parasite of Boops boops off Algeria and also investigated its diet to address whether Cy. bellones is indeed a hyperparasite, i.e., whether it feeds on the isopod. We also compared the body shape of various monogeneans belonging to the same family as Cy. bellones, the Diclidophoridae, including Choricotyle cf. chrysophryi Van Beneden & Hesse, 1863, collected from Pagellus acarne off Algeria. No morphological character of the anterior organs suggested any special adaptation in Cy. bellones to the perforation of the crustacean cuticle. The wall of the oesophagus and of the intestine of Cy. bellones was lined with a dark pigment similar to what is usually observed in haematophagous polyopisthocotyleans, and which is derived from ingested fish blood. We noticed that an anterior elongate stem exists only in diclidophorids dwelling on parasitic isopods and never in those attached to the gills. We hypothesize that the anterior stem of the body of Cy. bellones is an anatomical adaptation for the monogenean to feed on the fish while dwelling on the isopod. We thus consider that Cy. bellones is an epibiont of the parasitic crustacean, as it uses it merely as an attachment substrate, and is not a true hyperparasite.