Life cycle and structure of the fish digenean Brachyphallus crenatus (Hemiuridae).

Cystophorous cercariae from Retusa obtusa (Montagu) (Gastropoda, Opisthobranchia, Retusidae) develop into adults of Brachyphallus crenatus (Rudolphi, 1802) Odhner, 1905 (Hemiuridae). The free-swimming cercariae were ingested by laboratory-reared Acartia tonsa Dana, and the cercarial body was injected into the hemocoel of the copepod. Two-week-old metacercariae held at 15 C were infective to stickleback Gasterosteus aculeatus Linnaeus. The cercariae of B. crenatus are very similar to the cercariae of Hemiurus luehei Odhner, 1905, and Lecithocladium excisum (Rudolphi, 1819) Lühe, 1901 (Hemiuridae), which develop in closely related opisthobranch snails. Scanning electron microscopy of metacercariae and adults of B. crenatus revealed the annular plications of most of the external surface to be scalelike. The area surrounding the genital pore and the presomatic pit was densely plicated.     

On Podocotyle scorpaenae,Poracanthium furcatum and Derogenes latus,three poorly known digenean parasites of western Mediterranean teleosts

Three little-known digeneans, two opecoelids and a derogenid, from marine fishes off Corsica are redescribed and their systematics discussed. Distoma scorpaenae Rudolphi, 1819, from Scorpaena porcus, S. scrofa and S. notata, is transferred to the genus Podocotyle as P. scorpaenae (Rudolphi, 1819) n. comb. The authority for the taxon Poracanthium furcatum is amended to Dollfus (1948). This species is described from Mullus surmuletus and distinguished from Opecoeloides furcatus (Bremser in Rudolphi, 1819). Derogenes latus Janiszewska, 1953 is redescribed from Mullus surmuletus and discussed in relation to D. ruber Lühe, 1900.     

Karyological studies on three strigeid digeneans: Ichthyocotylurus erraticus (Rudolphi, 1809), I. variegatus (Creplin, 1825) and Apatemon gracilis (Rudolphi, 1819)

Previous work has shown that karyology may be a valuable technique for discriminating morphologically similar species. In the present study, chromosome number and morphology were described for three strigeid species, Ichthyocotylurus erraticus (Rudolphi, 1809), I. variegatus (Creplin, 1825) and Apatemon gracilis (Rudolphi, 1819). The results show that these species possess the same diploid number of chromosomes (2n = 20) in somatic cells. The relative length and the position of the centromere were determined, and significant inter-specific differences in the karyotypes are demonstrated, enabling the ready discrimination of I. erraticus and I. variegatus cercariae. A review of known karyotypes of the family Strigeidae suggests that possible routes of evolutionary changes involve pericentric inversions within chromosomes rather than Robertsonian translocations between elements.     

Larval trematodes (Digenea) of planorbid snails (Gastropoda: Pulmonata) in Central Europe: a survey of species and key to their identification

A survey of the larval stages (cercariae and metacercariae) of trematodes (Digenea) found in planorbid snails in Central Europe (Austria, Czech Republic, south-east Germany, Hungary, Poland and the Slovak Republic) is presented based on a study of 7,628 snails of 12 species examined between 1998-2006. A total of 34 trematode larval stages, comprising cercariae of 28 species and metacercariae of seven species (one species occurred both as cercaria and metacercaria) of nine families were found in 898 (11.5%) snails of eight species. The dominant cercariae were those belonging to the Rubenstrema exasperatum (Rudolphi, 1819)/Neoglyphe locellus (Kossack, 1910) species complex, Tylodelphys excavata (Rudolphi, 1803) and Echinostoma spiniferum (La Valette, 1855) sensu Nasincová (1992), all from Planorbarius corneus (Linnaeus). Almost the same spectrum of cercariae of the families Echinostomatidae, Plagiorchiidae and Omphalometridae was found in the present study as in previous reports; however, a considerably lower spectrum of cercariae of the families Diplostomidae and Strigeidae was recorded. The most frequent metacercariae were those of Echinoparyphium aconiatum Dietz, 1909, Neoglyphe locellus and Moliniella anceps (Molin, 1859), all occurring mainly in P. corneus. The most heavily infected snail species was P. corneus, followed by Planorbis planorbis (Linnaeus) and Segmentina nitida (Müller). The widest spectrum of trematode species was found in P. planorbis and P. corneus. Forty-two cercariae identified to the species level belonging to 15 families, plus an additional 43 taxa recorded under generic or provisional names, were reported from 11 species of planorbids in previous studies carried out in Central Europe. However, the actual number of trematode species occurring in the planorbid snails is probably much lower, because many, if not most, larval stages reported under provisional names or unidentified to the species level may be conspecific with identified adult forms. A key to the cercariae and metacercariae recorded from planorbids in Central Europe, together with illustrations of those species encountered most frequently in the field, is provided to facilitate identification.     

Chemical Nature and Mode of Stabilization of Egg-shell in Helicometra pulchella (Rudolphi, 1819) (Digenea: Opecoelidae)

The chemical nature and mode of stabilization of egg-shell protein in digenetic trematode Helicometra pulchella (Rudolphi, 1819) have been investigated using histochemical techniques. It was found that the egg-shell is stabilized by quinone-tanning together with dityrosine. Other structural proteins (elastin, collagen and keratin-like proteins), glycogen and acid mucopolysaccharides were absent in egg-shell. Tyrosine was present in vitelline cells and immature egg-shell indicating that the proteins involved in quinone-tanning were tyrosine rich and tyrosyl residues are modified to form dityrosine in mature egg-shell.     

Cestodes of the family Dilepididae (Cestoda:Cyclophyllidea) from fish-eating birds in Mexico: a survey of species

A survey of adults of dilepidid tapeworms (Cyclophyllidea) from piscivorous birds from Mexico is presented on the basis of the taxonomic evaluation of freshly collected and voucher specimens. The following species are reported (first records from Mexico marked with an asterisk): Cyclustera capito (Rudolphi, 1819); ^* C. ibisae (Schmidt & Bush, 1972); ^* Dendrouterina ardeae Rausch, 1955; ^* D. herodiae Fuhrmann, 1912; ^* D. papillifera (Fuhrmann, 1908); Glossocercus auritus (Rudolphi, 1819); ^* Neogryporhynchus cheilancristrotus (Wedl, 1855); Paradilepis caballeroi Rysavy & Macko, 1973; Paradilepis sp.; Parvitaenia cochlearii Coil, 1955; and Valipora mutabilis Linton, 1927. Dendrouteria herodiae is reported from America for the first time. New definitive hosts are Phalacrocorax olivaceus for C. capito, N. cheilancristrotus and P. caballeroi; Casmerodius albus and Egretta thula for G. auritus; and E. thula for D. herodiae. Data on the morphology of the rostellar hooks of all species, their hosts and distribution in Mexico are provided.     

Metacestodes of the family Dilepididae (Cestoda: Cyclophyllidea) parasitising fishes in Mexico

A survey of metacestodes of dilepidid tapeworms (Cyclophyllidea) occurring in fish from Mexico is presented. They belong to the following species (those first reported from Mexico marked with an asterisk): Cyclustera capito (Rudolphi, 1819); ^* Cyclustera cf. ralli (Underwood & Dronen, 1986); Dendrouterina pilherodiae Mahon, 1956; ^* Glossocercus auritus (Rudolphi, 1819); ^* G. caribaensis (Rysavy & Macko, 1973); ^* Paradilepis caballeroi Rysavy & Macko, 1973; ^* Paradilepis cf. urceus (Wedl, 1855); ^* Paradilepis sp.; Parvitaenia cochlearii Coil, 1955; ^* Parvitaenia macropeos (Wedl, 1855); ^* Valipora campylancristrota (Wedl, 1855); ^* V. mutabilis Linton, 1927; and ^* V. minuta (Coil, 1950). Metacestodes of Dendrouterina papillifera (Fuhrmann, 1908), previously reported from the gall-bladder of the pimelodid catfish Rhamdia guatemalensis from Mexico by Scholz et al. (1996), belong actually to V. minuta. Data on the morphology of metacestodes, their fish hosts and rate of infection, site and distribution in Mexico are provided.     

Critical studies on the genus Callitetrarhynchus (Cestoda: Trypanorhyncha) with recognition of Rhynchobothrium speciosum Linton, 1897 as a valid species of the genus Callitetrarhynchus

Summary Callitetrarhynchus speciosus (Linton, 1897) n. comb. for Rhynchobothrium speciosum is redescribed from Pomatomus saltatrix and is compared with the only other species of the genus. C. gracilis (Rudolphi, 1819), also found in the same fish. The arrangement of hooks on the tentacle of both species is illustrated. The two species, which have been included under the name C. gracilis in the past, differ mainly in the oncotaxy, different shape of the hooks of the chainette, distinct distribution of frontal glands and in the different depth of the marginal bothidial groove. ac]19840904     

The Opecoelidae (Digenea) of sparid fishes of the western Mediterranean. I. Pachycreadium Manter, 1954

Problems of the systematics of the Opecoelidae in the Mediterranean region are discussed. The genus Pachycreadium Manter, 1954 is redefined and its validity commented upon. Pachycreadium carnosum (Rud., 1819) is described from Sparus pagrus and Pagellus erythrinus off Corsica (Scandola) and compared with P. gastrocotylum (Manter, 1940) and P. lerneri Sogandares-Bernal, 1959.

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Résumé Les problèmes concernant la systématique des Opécoelidés de la région méditerranéenne sont abordés. Les auteurs redéfinissent et discutent la validité du genre Pachycreadium Manter, 1954. Pachycreadium carnosum (Rudolphi, 1819) est décrit à partlr d'exemplaires parasites de Sparus pagrus et de Pagellus erythrinus des côtes de Corse (Scandola), puis comparé à P. gastrocotylum (Manter, 1940) et à P. lerneri Sogandares-Bernal, 1959.

     

Variation in the morphology of adult Apatemon gracilis Rudolphi, 1819 (Digenea: Strigeidae) reared in different avian hosts

Adult Apatemon gracilis (Rudolphi, 1819) were reared experimentally in three different avian hosts: herring gulls Larus argentatus Gmelin, domestic chicks Gallus gallus (L.) and eider ducklings Somateria mollissima (L.). Comparisons of size, body proportions and fecundity were made between these and specimens obtained from a naturally infected goosander Mergus merganser L. The eider duck proved to be a suitable experimental host, rearing adults of comparable size and fecundity to those from the natural host. The growth and development of the parasite in domestic chicks and herring gulls were significantly reduced. Similar conditions are likely to exist in the natural environment and this should be taken into consideration when choosing experimental hosts for use in the laboratory or when identifying species.     

Clinostomum complanatum and Clinostomum marginatum (Rudolphi, 1819) (Digenea: Clinostomidae) are separate species based on differences in ribosomal DNA

Infections by metacercariae of Clinostomum (Leidy, 1856) species adversely affect aquacultured fish and are potentially transmissible to humans. Molecular methodologies are efficient tools, which enable diagnosis of all life-history stages of trematodes in their diverse hosts. The small subunit of ribosomal DNA genes of adults of the Old World Clinostomum complanatum (Rudolphi, 1819) and the New World Clinostomum marginatum (Rudolphi, 1819), obtained from a little egret Egretta garzetta (Linnaeus, 1766) and the great blue heron Ardea herodias (Linnaeus, 1758), respectively, were amplified, sequenced, and aligned. The resulting alignment was used to develop a genetic assay to differentiate between these species.     

Descriptions of digeneans from <Emphasis Type="Italic">Sardina pilchardus</Emphasis> (Walbaum) (Clupeidae) off the Algerian coast of the western Mediterranean,with a complete list of its helminth parasites

Five species of digeneans parasitic in the pilchard Sardina pilchardus (Walbaum), a little studied host, from off the Algerian coast of the western Mediterranean are redescribed. These are Parahemiurus merus (Linton, 1910) Manter, 1940, Aphanurus stossichii (Monticelli, 1891) Looss, 1907, Aphanurus virgula Looss, 1907, Lecithaster confusus Odhner, 1905 and Pronoprymna ventricosa (Rudolphi, 1819) Poche, 1926. One of these, A. virgula, is a new record for this host. One other digenean, Hemiurus luehei Odhner, 1905, was also recorded from this host. A complete checklist of the helminth parasites of S. pilchardus throughout its distributional range, comprising 104 host-parasite records of 39 taxa, is presented.     

<Emphasis Type="Italic">Clestobothrium gibsoni</Emphasis> n. sp. (Cestoda: Bothriocephalidae) from the bullseye grenadier <Emphasis Type="Italic">Bathygadus macrops</Emphasis> Goode &; Bean (Macrouridae) in the Gulf of Mexico

Clestobothrium gibsoni n. sp. is described from the intestine of the bullseye grenadier Bathygadus macrops (Macrouridae) collected in the northeastern Gulf of Mexico. The new species can be distinguished from both C. crassiceps (Rudolphi, 1819), the type-species of the genus, and C. neglectum (Lönnberg, 1893), the second species in the genus, by its unique ovary, which is transversely elongate and tapered on both ends rather than being U-or H-shaped, and by having more testes (60-65 vs 40-50 and 35-45 per proglottid). The new species is also compared to Bothriocephalus acheilognathi Yamaguti, 1934 and B. kivuensis Baer & Fain, 1954, two species with similar scoleces which have previously been assigned to Clestobothrium . The generic diagnosis of Clestobothrium is amended to include species with either anoperculate or operculate eggs. This is the first report of an adult tapeworm from a species of Bathygadus , and the first report of a species of Clestobothrium Lühe, 1899 (Bothriocephalidae) from the Gulf of Mexico.     

The life-cycle of Plagiorchis maculosus (Rudolphi, 1802) Braun, 1902 (Trematoda: Plagiorchiidae), a parasite of swallows (Hirundinidae)

During 1984 eggs of Plagiorchis maculosus were obtained from the faeces of naturally infested nestlings of Hirundo rustica and Delichon urbica near Ulm, Federal Republic of Germany. Developmental stages and adults were reared in the laboratory using Lymnaea stagnalis and Radix auricularia for daughter-sporocysts and cercariae, larvae of Chaoborus for metacercariae, and a canary for adults. Eggs from the faeces of the canary were reared once more up to the metacercarial stage for comparison. Infection experiments were negative with Radix peregra and Galba palustris as first intermediate hosts and chickens as final hosts. The stages of the life-cycle are figured and described in detail, including the chaetotaxy of the cercaria. Characteristics distinguishing P. maculosus from related species are discussed. A medium for in vitro excystation of metacercariae is presented. It is suggested that the range of the final hosts and the geographical distribution of P. maculosus be reconsidered in the light of study of its larval stages. ac]19860715     

Prosorhynchoides gracilescens (Rudolphi, 1819) (Digenea: Bucephalidae) from Lophius piscatorius L. is a species complex: a redescription of this species (sensu stricto) from the western Mediterranean and the description of P. borealis n. sp. from the northern North-East Atlantic

The bucephalid digenean Prosorhynchoides gracilescens (Rudolphi, 1819) is a common intestinal parasite of the angler fish Lophius piscatorius in European marine waters. Detailed studies of new material collected off the coasts of both Marseilles and Corsica in the western Mediterranean, and comparison with museum material from the northern North-East Atlantic, indicated that the accepted concept of this species comprises two distinct taxa. The Mediterranean form occurs in relatively small numbers and has small eggs, a large rhynchus and a vitelline distribution that finishes well short of the rhynchus, whereas the NE Atlantic form, which comprises the majority of records, occurs often in large numbers, has larger eggs, a relatively smaller rhynchus and a vitelline distribution that tends to reach the rhynchus. Since the type-material is from the Mediterranean and resembles the Mediterranean form, there was little option but to consider the latter as P. gracilescens (sensu stricto) and to describe the NE Atlantic form as a new species, for which the name P. borealis n. sp. is coined to reflect its northerly distribution. Both species are described and figured in detail, and a table and illustration of the diagnostic features are presented. In addition, some discussion is included on the distribution of these two species and whether P. gracilescens (s. str.) might be a relict species, and on non-European records of P. gracilescens (sensu lato).     

In vitro Excystation of Metacercariae of Clinostomum complanatum (Rudolphi, 1819) (Digenea: Clinostomatidae)

In vitro excystation of metacercariae of Clinostomum complanatum (Rudolphi, 1819) was studied. Excystation was an active process, initiated by a rise in temperature. The metacercariae excysted in enzymic as well as non enzymic medium, but the rate of excystation was affected by the temperature and/or pH of the medium. The optimal excystation was obtained in pepsin-Tyrode at pH 2.3-3.5 and a temperature of 42°C. Trypsin treatment was not required.     

Analyse phénétique des Microphalloidea (Trematoda) d'après la chétotaxie des cercaires

Résumé L'intérêt principal de la chétotaxie des cercaires de Digènes réside dans sa relation avec le système nerveux très stable et à évolution très lente. L'analyse phénétique de la chétotaxie des cercaires est réalisée chez 12 Microphallidae, dont cinq Maritrema, cinq Microphallus, un Megalophallus, un Gynaecotyla, trois Lecithodendriidae, dont un Pseudocephalotrema, un Prosotocus, un Pleurogenoides et trois Renicolidae: Renicola sp., Cercaria sp. 7 et Cercaria sp. 8 de Richard (1971). Les sensilles des cercaires sont mises en évidence par imprégnation au nitrate d'argent. Il est admis qu'une ou plusieurs sensilles, repérées dans un même site chez des cercaires différentes, sont homologues et, qu'au cours de l'évolution, la chétotaxie tend à se compliquer. Aux niveaux pris en compte, les sensilles sont répertoriées en absence, présence et nombre. Ceci permet de classer les cercaires de la plus simple à la plus complexe, à l'intérieur de chaque genre, puis de proche en proche au sein d'une même famille. Les familles peuvent être comparées entre elles, à leur tour. Le total des sensilles C+A_ID+P+U est de 36 à 47 pour les Maritrema, 40 à 52 pour les Microphallus, 51 à 52 pour Megalophallus, 57 à 58 pour Gynaecotyla. Ces cercaires n'ont ni acétabulum, ni sensille S. Le total correspondant est de 56 à 64 pour Pseudocephalotrema, 60 à 68 pour Prosotocus, 66 à 72 pour Pleurogenoides, 67 à 79 pour Renicola. Ces cercaires ont un acétabulum et le nombre de sensilles S doit s'ajouter au total des autres papilles prises en compte. Ces données suggèrent que, dans l'ensemble analysé, le genre Maritrema est le plus primitif et Renicola le plus évolué. Les auteurs admettent une origine commune aux trois familles considérées et proposent leur regroupement en superfamille Microphalloidea.La chétotaxie des Plagiorchioidea est connue pour les cercaires de Cephalogonimus. Plagiorchis, Astiotrema, Leptophallus, Opisthioglyphe, Haplometra, Haematoloechus, Skrjabinoeces, Macrodera et Omphalometra. Toutes ces cercaires ont plus de 80 sensilles C+A_ID+P+U et présentent une relative homogénéité; pour ces raisons, seule la chétotaxie d'Omphalometra est comparée à celle des 16 Microphalloidea. Cette comparaison paraît exclure l'hypothèse d'une origine plagiorchioïde des Microphallidae. Dans le sous-ordre des Plagiorchiata, la superfamille Microphalloidea serait la plus primitive.

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The main interest of digenean cercarial chaetotaxy lies in its close association with the nervous system, which is very stable and evolves very slowly. A phenetic analysis of the chaetotaxy was completed for the following: (i) 12 microphallids, including five Maritrema spp., five Microphallus spp., one Megalophallus sp. and one Gynaecotyla sp., (ii) three lecithodendriids, including one Pseudocephalotrema sp., one Prosotocus sp. and one Pleurogenoides sp.; (iii) three renicolids, Renicola sp., Cercaria sp. 7 and Cercaria sp. 8 of Richard (1971). The cercarial sensilla were stained using a silver nitrate impregnation technique. It was assumed that, when one or several sensilla are observed in the same locus in different cercariae, they are homologous, and that, during the course of evolution, chaetotaxy becomes more complicated. At each locus, the presence or absence and the number of sensilla were listed. This allowed a classification of the cercariae from the simplest to the most complex, firstly within each genus and subsequently within the same family. The families themselves were then compared. The total number of sensilla, C+A_ID+P+U, was 36–47 in Maritrema, 40–52 in Microphallus, 51–52 in Megalophallus and 57–58 in Gynaecotyla. These cercariae have no acetabulum or S sensilla. The total number of sensilla, C+A_ID+P+U, was 56–64 in Pseudocephalotrema, 60–68 in Prosotocus, 66–72 in Pleurogenoides and 67–79 in Renicola. These cercariae have an acetabulum and the number of the S sensilla must be added to the total. These data suggest that, within the sample analysed, the genus Maritrema is the most primitive and the genus Renicola the most evolved. The authors assume that the three families studied here have a common origin and may be grouped together in the superfamily Microphalloidea. The cercarial chaetotaxy of the Plagiorchioidea is known for Cephalogonimus, Plagiorchis, Astiotrema, Leptophallus, Opisthioglyphe, Haplometra, Haematoloechus, Skrjabinoeces, Macrodera and Omphalometra. All of these cercariae exhibit more than 80 C+A_ID+P+U sensilla and display a relative homogeneity; for these reasons, only the chaetotaxy of Omphalometra is compared with those of the 16 microphalloids. This comparison allows us to reject the hypothesis for the origin of the Microphalloidea within the Plagiorchioidea. In the suborder Plagiorchiata, the superfamily Microphalloidea appears to be the most primitive.