Seasonal and yearly population dynamics of two exotic helminths, Camallanus coti (Nematoda) and Bothriocephalus acheilognathi (Cestoda), parasitizing exotic fishes in Waianu Stream, O'ahu, Hawaii

Exotic poeciliid fishes introduced into Hawaiian freshwaters are responsible for the introduction of several exotic parasites, of which the most important are Camallanus cotti and Bothriocephalus acheilognathi in terms of potential disease threat to native stream fishes. This roundworm and tapeworm are the most prevalent and abundant freshwater fish helminths in Hawaiian streams. This study examined the seasonal and yearly population structure of C. cotti and B. acheilognathi to determine if the tropical Hawaiian environment characterized by low climatic variability permits continuous opportunities for parasite transmission regardless of time of year. Camallanus cotti displayed seasonal differences in prevalence and mean abundance, whereas B. acheilognathi did not. Camallanus cotti prevalence and mean abundance were higher in the Hawaiian summer (47.7%, 0.79) than in winter (25.8%, 0.36). A seasonal relationship of C. cotti levels is likely explained by extensive rains associated with the Hawaiian winter season, which may act to decrease parasite transmission by flushing infected poeciliid hosts, intermediate copepod hosts, and possibly free-living infective worm stages downstream. Bothriocephalus acheilognathi displayed low prevalence and mean abundance in both summer (4.0%, 0.06) and winter (6.5%, 0.07), and it may be difficult to detect seasonal changes due to these low levels. Camallanus cotti prevalence and mean abundance remained relatively constant from the summer of 1995 to the summer of 1999, indicating that levels of this roundworm are stable in Waianu Stream. Whereas B. acheilognathi prevalence and mean abundance were low during the summer of 1995 and the summer of 1997, a dramatic peak in prevalence and mean abundance was observed in the summer of 1998 (41.2%, 1.06), with levels decreasing sharply in the summer of 1999 (4.4%, 0.07). It appears that B. acheilognathi also is present in stable populations at low levels, even though levels rose sharply during a single year.     

Intestinal helminths of some Nile fishes near Cairo, Egypt with redescriptions of Camallanus kirandensis Baylis 1928 (Nematoda) and Bothriocephalus aegyptiacus Rysavy and Moravec 1975 (Cestoda)

Of 10 species of Nile fishes collected during the summer of 1975 at Giza near Cairo, Egypt, 7 harbored 7 helminth species. Recovered material includes 3 species of nematodes: Camallanus kirandensis Baylis 1928 (new host and geographical record), Cucullanus barbi Baylis 1923, and Rhabdochona congolensis Campana-Rouget 1961 (new host record); three species of cestodes: Khawia sp. (new in Africa), Polyonchobothrium clarias (Woodland 1925) Meggitt 1930, and Bothriocephalus aegyptiacus Rysavy and Moravec 1975; and one acanthocephalan species, Acanthosentis tilapiae Baylis 1947 (new geographical record). Morphologic observations of each species are reported. C. kirandensis and B. aegyptiacus are redescribed.     

Camallanus cotti Fujita, 1927 (Nematoda, Camallanoidea) in ornamental aquarium fishes: pathology and morphology

The pathology induced by the nematode Camallanus cotti in the aquarium fishes Beta splendens (beta fish) and Poecilia reticulata (guppy) consisted of gross and microscopic lesions, the former characterized by abdominal swelling with reddish parasites protruding from the anus in both fish hosts and the latter, similar in the beta fishes and guppies, by hemorrhage, congestion, edema, a few glandular elements, and extensive erosion areas in the rectum mucosa, with a marked thickening of the wall and absence of inflammatory infiltrate. Lesions were associated with the presence of several worms attached to the wall or free in the rectal lumen. This is the second reference of the parasite in Brazil and the first report of pathological findings related to this nematode species that is also briefly redescribed and illustrated for the first time on the basis of Brazilian samples.     

Bothriocephalus acheilognathi (Cestoda) in the endangered fish Profundulus hildebrandi (Cyprinodontiformes), Mexico

The Asian fish tapeworm, Bothriocephalus acheilognathi, has been considered one of the most dangerous parasites for cultured carp and a risk for native freshwater fish populations worldwide. This cestode is highly pathogenic for fishes especially fry. In this paper we record B. acheilognathi parasitizing the endangered and endemic freshwater fish Profundulus hildebrandi from the endorheic basin of San Crist6bal de las Casas, Chiapas, Mexico. B. acheilognathi was recorded from 10 of the 11 sampled localities, with high values of prevalence (> 60%) and mean abundance (> 4.50). The infection was persistent all through the year; gravid cestodes were recorded in all samples. It is assumed that B. acheilognathi entered to this area through the introduction of common carp Cyprinus carpio, for aquacultural purposes. The data presented in this paper document the successful introduction, colonization and establishment of this alien species into the endangered P. hildebrandi.     

Geographical divergence in Bothriocephalus (Cestoda) of fishes demonstrated by enzyme electrophoresis

Geographical divergence in Bothriocephalus (Cestoda) of fishes demonstrated by enzyme electrophoresis. International Journal for Parasitology16: 553–558. The study of the geographical differentiation of two Bothriocephalus species, B. gregarius a parasite of Psetta maxima and B. barbatus a parasite of Scophthalmus rhombus, has revealed that, whereas Atlantic and Mediterranean populations of B. barbatus are genetically similar, those of B. gregarius present important genetic differences.     

First identification of eggs of the Asian fish tapeworm Bothriocephalus acheilognathi (Cestoda: Bothriocephalidea) in human stool

We report the first case of egg isolation of the Asian fish tapeworm Bothriocephalus acheilognathi (Bothriocephalidea) from human stool. A male patient from Saint Laurent du Maroni (French Guiana) presenting abdominal pain was examined in France for the diagnosis of intestinal parasites. Diphyllobothrium-like eggs were observed in his stool. However, molecular phylogenetic analyses based on sequences of rDNA and COI genes showed that the eggs observed belong to a bothriocephalidean cestode B. acheilognathi. The adult life stages of B. acheilognathi cestodes are known as invasive parasites of a wide spectrum of fish; however, they have not been described to parasitize any mammals. This human infection seems to be accidental and represents a parasite passage through human intestine after the consumption of an infected fish host.     

The development and morphogenesis of Camallanus cotti Fujita, 1927 (Nematoda: Camallanidae), with notes on its phylogeny and definitive host range

The freshwater fish nematode Camallanus cotti Fujita, 1927 (Spirurida: Camallanidae) is naturally distributed in East, South and Southeast Asia. During the past three or four decades the species has been disseminated to Europe, North America, Australia and Hawaii, mainly due to the extensive ornamental fish trade. In the present study, its development and larval morphogenesis is described. Newborn first-stage larvae are ingested by copepods and within hours reach the haemocoel, where the worms moult twice. At 22°C ambient temperature, fully-developed third-stage larvae appear on day 11 p.i. After transmission into the fish intestine two further moults occur before the adult stage is reached. At 23°C water temperature, the final moult is initiated around day 33 p.i. in males and between 34 and 42 days p.i. in females. Morphologically the young and older adults are similar, but the buccal capsule of both young males and young females is not yet fully sclerotised. Based on the close similarity in the development and adult morphology of the buccal capsule in C. cotti and three congeners from Europe and North America, we suggest, in general agreement with earlier workers, that the Camallanus Railliet & Henry, 1915 originated in tropical Asia and subsequently radiated to species when adapting to new climatic and/or host-related conditions in the Old World and the New World. C. cotti may thus represent a lineage of speciation which did not apparently involve extensive changes in relation to their natural geographical distribution or definitive host range.     

Molecular variation of Bothriocephalus acheilognathi Yamaguti, 1934 (Cestoda: Pseudophyllidea) in different fish host species based on ITS rDNA sequences

The molecular variation in Bothriocephalus acheilognathi Yamaguti, 1934 from 11 species of freshwater fish collected in Australia, China, the Czech Republic, England and Hawaii was investigated by determining the nucleotide sequences of the internal transcribed spacer region. The length of the first and second internal transcribed spacer sequences of multiple individuals ranged from 553 to 571 bp and 553 to 615 bp, and the G + C content from 53.1 to 53.5%. The percentage sequence divergence varied between 0 and 0.9% in the ITS1 and 0 and 6.6% in the ITS2, respectively, indicating the occurrence of intraspecific variation. It is demonstrated that the fragment length variation resulted primarily from microsatellite polymorphisms present in the ITS region, especially in the ITS2 region. Phylogenetic analyses revealed that B. acheilognathi examined in this study consisted of three closely related genotypes with certain degrees of host-specificity, and the genotype representing isolates from Cyprinus carpio L. was the most common and diverse form within the species B. acheilognathi.     

A revision of the species of Bothriocephalus Rudolphi, 1808 (Cestoda: Pseudophyllidea) parasitic in American freshwater fishes

The species of the pseudophyllidean genus Bothriocephalus Rudolphi, 1808 parasitising freshwater fishes in America are revised, based on the examination of type and voucher specimens of seven taxa. There are five valid species: Bothriocephalus claviceps (Goeze, 1782), B. cuspidatus Cooper, 1917, B. formosus Mueller & Van Cleave, 1932, B. acheilognathi Yamaguti, 1934, and B. pearsei Scholz, Vargas-Vázquez & Moravec, 1996. B. texomensis Self, 1954 from Hiodon alosoides in the USA, and B. musculosus Baer, 1937 from a cichlid Cichlasoma biocellatum (= C. octofasciatum) which died in an aquarium in Switzerland, are synonymised with B. cuspidatus. B. schilbeodis Cheng & James, 1960 from Schilbeodes insignis in the USA, B. speciosus (Leidy, 1858) Leidy, 1872 from Boleostoma olmstedi in the USA, and B. cestus Leidy, 1885 from Salvelinus sp. in Canada are considered to be species inquirendae until new material for the evaluation of their taxonomic status is available. B. cordiceps (Leidy, 1872) from Salmo (= Salvelinus) fontinalis in North America is in fact a larva (plerocercoid) of a Diphyllobothrium species. The study showed that there have been many misidentifications, mostly of B. cuspidatus erroneously designated as B. formosus or B. claviceps. The five valid species are redescribed and illustrated, with emphasis on scolex morphology. The distribution of individual taxa and the spectrum of their definitive hosts are briefly reviewed and a key facilitating identification of individual species is also provided.     

A new Huffmanela species (Nematoda: Trichosomoididae) parasitizing atherinid fishes in north Patagonian Gulfs, Argentina

Huffmanela moraveci n. sp. (Nematode: Trichosomoididae) is described from the skin of fins and gills of the silversides Odontesthes smitti Lahille, 1949, and Odontesthes nigricans Richardson, 1848 (Pisces: Atheriniformes), from southwestern Atlantic coast, on the basis of the morphology of adults and eggs found in the host tissues. Huffmanela moraveci n. sp. can be distinguished from Huffmanela carcharini, H. banningi, H. japonica, H. mexicana, H. paronai, H. schouteni, H. shikokuensis, H. branchialis, H. filamentosa, H. ossicola, and H. lata by the size and shape of the eggs. The adult stage of H. moraveci n. sp. can be differentiated from H. hufmani and H. canadensis by the position of the nerve ring and by the total esophagus length/body length ratio. Huffmanela moraveci n. sp. also differs from H. huffmani by the presence of bacillary bands and by the body length. This is the first report of a species of Huffmanela in South America, the first report of a species of Huffmanela with Odontesthes spp. as host, and the third known adult form in the genus.     

Redescription of Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 (Nematoda: Camallanidae) and its first record from fishes in China

The nematode Camallanus hypophthalmichthys Dogel and Akhmerov, 1959 is redescribed from specimens collected from the intestine of the bighead carp Aristichthys nobilis, from Liangzihu Lake (Yangtze River basin), Hubei Province, central China. The light and scanning electron microscopical examination made it possible to study in detail the morphology of this so far little-known species and to confirm its validity. The main specific features of C. hypophthalmichthys distinguishing it from the most similar Camallanus spp. is the presence of 3 small caudal processes on the male tail tip, 13-16 longitudinal ridges on the inner surface of the valve of the buccal capsule, and the arrangement of preanal and postanal genital papillae in the male. This finding represents a new host record, the first record of this parasite in the Yangtze River basin, and the first documented record of C. hypophthalmichthys from China. Camallanus hypophthalmichthys is considered a specific intestinal parasite of fishes of the cyprinid Hypophthalmichthyinae.     

New genus, new species of Cestoda (Anoplocephalidae), new species of Nematoda (Cosmocercidae) and other helminths in Cyrtodactylus louisiadensis (Sauria: Gekkonidae) from Papua New Guinea

Gekkotaenia novaeguineaensis n. gen., n. sp. (Cestoda: Anoplocephalidae) from the small intestine and Cosmocerca zugi n. sp. (Nematoda: Cosmocercidae) from the large intestine of the ring-tailed gecko, Cyrtodactylus louisiadensis (Sauria: Gekkonidae) are described and illustrated. Gekkotaenia novaeguineaensis n. gen., n. sp. is unique among the acraspedote Linstowiinae in possessing a poral female reproductory system. Cosmocerca zugi n. sp. is the 22nd species to be assigned to the genus and differs from other species in the genus by possessing 4 pairs of rosette papillae on plectanes and having a gubernaculum longer than the spicules. It is the fifth species to be described from the Australian biogeographical region. Eight additional helminth species were found: the digenean, Allopharynx macallisteri; 2 cestodes, cysticercoids of Cyclophyllidea gen. sp. and tetrathyridia of Mesocestoides sp.; 5 nematodes, larvae in cysts of Abbreviata sp., Aplectana macintoshii, Oswaldocruzia bakeri, Parapharyngodon maplestonei, and an undescribed species of Physalopteroides. Cyrtodactylus louisiadensis represents a new host record for each of these helminths.     

Effects of the Nematode Parasite Camallanus cotti on Sexual and Non-Sexual Behaviors in the Guppy (Poecilia reticulata)

Since the publication of Hamilton and Zuk's model of sexualselection there have been many studies on the effects of parasiteinfection on host mate choice and sexual behavior. In this paperI discuss the effects of nematode parasites on sexual behaviorin the guppy and the parallel effectson non-sexual behavior.This more general approach allows a test of the hypothesis thatsexual displays are particularly selected to reveal parasiteinfection in the host.     

Bothriocephalus gadellus n. sp. (Cestoda: Bothriocephalidae) from the beardless codling Gadella imberbis (Vaillant) (Moridae) in the southwestern Gulf of Mexico,with a review of species of Bothriocephalus Rudolphi, 1808 reported from gadiform fishes

Bothriocephalus gadellus n. sp. is described from the intestine of the beardless codling Gadella imberbis (Gadiformes: Moridae) from the southwestern Gulf of Mexico. It resembles B. scorpii, the type-species of Bothriocephalus, and B. manubriformis, the only species of the genus reported from the Gulf of Mexico. B. gadellus n. sp. differs from both species in having four excretory canals on each side of the proglottid (three per side in B. scorpii; two per side anastomosing to form an extensive plexus throughout the medulla in B. manubriformis ), 24-33 testes per proglottid (30-60 in B. scorpii; 60-100 in B. manubriformis), a total length of 31-47 mm (32-950 mm in B. scorpii; 130-1,000 mm in B. manubriformis), and a seminal receptacle and wing-like expansions on each proglottid (absent in B. scorpii and B. manubriformis), as well as lacking two sets of reproductive organs per proglottid (present in B. scorpii) and a vagina with a bulbous sphincter near the opening (present in B. manubriformis). An amendment to the generic diagnosis of Bothriocephalus might be warranted if other species of this genus are found to possess a seminal receptacle. B. gadellus n. sp. appears to be like those species of Bothriocephalus that can utilise two intermediate hosts (copepod and fish). B. ellipticus and B. neglectus are designated as species inquirendae. This is the first report of a cestode from a morid fish in the Gulf of Mexico, and the first report of a parasite from a species of Gadellus.     

The population biology of Camallanus lacustris (Zoega) in eels, Anguilla anguilla (Linnaeus), and their status as its host

The population biology of Camallanus lacustris (Zoega) and the status of the eel, Anguilla anguilla (Linnaeus), as its definitive host have been studied in a small Devon lake. No clear seasonal pattern in prevalence and abundance was observed, and recruitment of the new generation may occur in all seasons. However, reproduction exhibits some seasonality as adult nematodes were the commonest stage in the parasite population from early summer onwards and production of first-stage larvae appeared to occur primarily during this period. These larvae were viable, and shown experimentally to be infective to copepods. The occurrence of the nematode and its development to full maturity in eels, the absence of its typical definitive host ( Perca fluviatilis Linnaeus) from the lake and the absence of the nematode from other species of fish in the lake indicate that eels serve as the only, true definitive host of the nematode in this locality. It is suggested that account must be taken of this alternative host when the population of C. lacustris is investigated in the future.     

Interplay of host specificity and biogeography in the population structure of a cosmopolitan endoparasite: microsatellite study of Ligula intestinalis (Cestoda)

Organisms with wide geographical or phenotypic diversity often constitute assemblages of genetically distinct species or lineages. Within parasites, an emergence of host-specific lineages is assumed to create such cryptic variability; however, empirical evaluation of these processes is scarce. Here, we analyse populations of a parasite with a complex life cycle, wide host spectrum and global distribution, with the aim to reveal factors underlying the evolution of host- or geography-dependent lineages. Using 15 microsatellite loci, deep genetic distances were observed between populations from distant geographical areas. On the local scale, host-mediated genetic structure was found among sympatric samples. Two lineages differing in the spectrum of infected hosts co-occurred in the Euro-Mediterranean area, and two distinct lineages were recovered from Lake Tana in Ethiopia. Although sampled across several host taxa and multiple localities, a lack of marked genetic structure was seen in the populations belonging to one of the European lineages. Only weak genetic differentiation between sympatric samples from two host species was found. Complexity of the parasite life-cycle contributed to such a stratified pattern. Differences in the immune response between fish hosts were suggested as the factor diversifying the populations locally; conversely, high mobility of the parasite due to migration with its bird (definitive) host were assessed to homogenize populations across the area of distribution. However, despite the high mobility, large bodies of salt water prevent the parasite from long-distance migrations, as was demonstrated in an example of the Mediterranean Sea which represented an effective barrier to gene flow.     

Variability and phenotypic structure of Proteocephalus torulosus (Cestoda: Proteocephalidea)--a parasite of cyprinid fishes

Variability of 5 qualitative features of Proteocephalus torulosus from 6 fish species belonging to 5 genera of the subfamily Leuciscinae was studied. Itraspecific diversity is represented by 3 scolex forms, 2 types of proglottid structure, 3 proglottid shapes, and 2 variations of the female reproductive system characteristics. The parasite living in different host species form separate ecological forms differing in the number of phenotypes and their ratio. However, the same scolex and strobila phenotypes dominate in the range of the parasite. Two P. torulosus groupings have been recognised the European and Asian ones, which differ in the representation of the proglottid structure types.