David I. Gibson

Keys to the Trematoda: Volume 1.

The authors are affiliated with the Natural History Museum, London. The list of contributors includes 15 international specialists from UK, USA, Australia, Bulgaria, Czech Republic and Poland. The trematodes are parasitic worms infecting all vertebrate groups, they include families of significance to human and animal health, with considerable economic impact. As affirmed in general introduction by the editors, the aim of this present work is to provide keys for the identification of the sexual adults of trematodes (normally found in vertebrate hosts). The present volume is composed of 53 chapters introducing classes, subclasses, superfamilies, families and genera of the Trematoda – a class of the phylum Plathelminthes (flatworms), which are commonly referred to as flukes. This class comprises two subclasses, the Aspidogastrea (chapter 2) and the Digenea (chapter 3 and the rest of chapters). Aspidogastreans are a small group composed only of a score of nominal genera parasitic in molluscs, fishes and chelonians. The Digenea are a much larger group, comprising more than 2500 nominal genera, the vast majority of which use molluscs as primary hosts and vertebrates as final hosts. Since the middle of the 19th century, various attempts have been made to find useful criteria upon which an acceptable classification of this subclass could be based. In the chapter 1 a key to both subclasses is given. Chapter 2 is devoted to the Aspidogastrea. Chapter 3 introduces Gibson, D. I., Jones, Arlene, Bray, R. A., editors

study and reorganization of Plagioporus Stafford, 1904 (Digenea: Opecoelidae) and related genera, with special reference to forms from European Atlantic waters

Summary The families Opecoelidae, Lepocreadiidae and Enenteridae are differentiated. The Enenteridae is considered to consist of three subfamilies, the Enenterinae, the Cadenatellinae subfam. nov. and the Pseudolepidapedinae, whose constituent genera are listed. The diagnostic features of the opecoelid subfamilies Opecoelinae, Plagioporinae and Stenakrinae are presented. Plagioporus is restricted to freshwater forms, and Lebouria is considered a synonym of Peracreadium, following the transfer of L. idonea Nicoll, 1909, to the latter genus as P. idoneum comb. nov. Caudotestis is considered to belong to the Stenakrinae, Trematichtys to the Allocreadiidae, Spinoplagioporus to the Enenterinae and Pycnadenoides to the Plagioporinae. Macvicaria gen. nov., with the type-species M. [Plagioporus] alacris (Looss, 1901) and also containing M. [Distoma] soleae (Dujardin, 1845) (syn. Plagioporus varius) is erected for some of the marine forms previously allocated to Plagioporus. Neolebouria is briefly discussed and N....

The evolutionary expansion and host-parasite relationships of the Digenea

Relevant data on the Digenea extracted from a host-parasite data-base are analysed in relation to host-groups, host-specificity, speciation, radiation and geographical distribution. The classification, evolution, co-evolution, and co-speciation of the group are discussed. Principal components analyses indicated that 119 families formed 11 groups in relation to their vertebrate hosts and the 55 families with molluscan records formed 6 groups in relation to their molluscan hosts. The most prominent host-groups are the Fish and Mammals. Individual digenean families did not exhibit the host combinations Fish+Birds, Fish+Mammals, Herpetiles+Birds and Herpetiles+Mammals. Families with Fish hosts tended to use Prosobranch and, to a lesser extent Bivalve, molluscs, whereas families in Herpetiles, Birds and Mammals tended to use Pulmonates. Families using 3 or 4 mixed vertebrate groups tended to use mixed molluscan groups. Families using Herpetiles as the vertebrate host tend to be the most host-specific and the least speciose, whereas those using 3 to 4 mixed vertebrate groups are the most speciose. In a detailed examination of three zoogonid genera, few indications of co-evolution with their vertebrate hosts were detected, and geographical information from the data-base appeared to shed no light upon the geographical origins of the Digenea. Some of these findings are commented upon in relation to the evolution of the Digenea.

Genetic and Morphological Approaches Distinguish the Three Sibling Species of the Anisakis simplex Species Complex, with a Species Designation as Anisakis berlandi n. sp. for A. simplex sp. C (Nematoda: Anisakidae)

Abstract:  Numerous specimens of the 3 sibling species of the Anisakis simplex species complex (A. pegreffii, A. simplex (senso stricto)), and A. simplex sp. C) recovered from cetacean species stranded within the known geographical ranges of these nematodes were studied morphologically and genetically. The genetic characterization was performed on diagnostic allozymes and sequences analysis of nuclear (internal transcribed spacer [ITS] of ribosomal [r]DNA) and mitochondrial (mitochondrial [mt]DNA cox2 and rrnS) genes. These markers showed (1) the occurrence of sympatry of the 2 sibling species A. pegreffii and A. simplex sp. C in the same individual host, the pilot whale, Globicephala melas Traill, from New Zealand waters; (2) the identification of specimens of A. pegreffii in the striped dolphin, Stenella coeruleoalba (Meyen), from the Mediterranean Sea; and (3) the presence of A. simplex (s.s.) in the pilot whale and the minke whale, Balaenoptera acutorostrata Lacépède, from the northeastern Atlantic waters. No F1 hybrids were detected among the 3 species using the nuclear markers. The phylogenetic inference, obtained by maximum parsimony (MP) analysis of separate nuclear (ITS rDNA region), combined mitochondrial (mtDNA cox2 and rrnS) sequences datasets, and by concatenated analysis obtained at both MP and Bayesian inference (BI) of the sequences datasets at the 3 studied genes, resulted in a similar topology. They were congruent in depicting the existence of the 3 species as distinct phylogenetic lineages, and the tree topologies support the finding that A. simplex (s.s.), A. pegreffii, and A. berlandi n. sp. (=A. simplex sp. C) represent a monophyletic group. The morphological and morphometric analyses revealed the presence of morphological features that differed among the 3 biological species. Morphological analysis using principal component analysis, and Procrustes analysis, combining morphological and genetic datasets, showed the specimens clustering into 3 well-defined groups. Nomenclatural designation and formal description are given for A. simplex species C: the name Anisakis berlandi n. sp. is proposed. Key morphological diagnostic traits are as follows between A. berlandi n. sp. and A. simplex (s.s.): ventriculus length, tail shape, tail length/total body length ratio, and left spicule length/total body length ratio; between A. berlandi n. sp. and A. pegreffii: ventriculus length and plectane 1 width/plectane 3 width ratio; and between A. simplex (s.s.) and A. pegreffii: ventriculus length, left and right spicule length/total body length ratios, and tail length/total body length ratio. Ecological data pertaining to the geographical ranges and host distribution of the 3 species are updated.

A catalogue of the nominal species of the monogenean genus Dactylogyrus Diesing, 1850 and their host genera

Dactylogyrus is the largest helminth genus, with more than 900 nominal species, and is consequently in a state of considerable confusion. In an attempt to consolidate our knowledge of this large taxon, this work surveys the nominal species and catalogues them and their hosts (to the generic level) in the form of a species list which is cross-referenced to host-parasite list. A reference list to the authorities for the taxa is included.

Digenean species diversity in teleost fish from a nature reserve off Corsica, France (Western Mediterranean), and a comparison with other Mediterranean regions

Data on the digenean parasites of 2238 teleosts from the Scandola Nature Reserve off Corsica are presented. These represent the largest general survey of digenean parasites attempted in the Mediterranean region and is the result of major collections and systematic reports published over the past 20 years. The number of different digenean species recorded from 63 fish species was 102. Full parasite-host and host-parasite lists are presented, with information on the geographical distribution of the parasites, their site within the host and the prevalence, adundance and intensity of the infections. The digenean fauna of teleosts off Corsica is compared with that in other regions of the Mediterranean and the Black Sea. A more detailed analysis of the diversity of these parasites in sparid fishes indicates that the digenean diversity off Corsica is far greater than that in other parts of the Mediterranean.

Studies on bucephalid digeneans parasitising molluscs and fishes in Finland I. Ecological data and experimental studies

Two types of bucephalid cercariae are reported from the bivalve Anodonta anatina in two Finnish lakes. One, Type A, resembles in gross morphology the cercaria of Bucephalus polymorphus, and the other, Type B, resembles the cercaria of Rhipidocotyle campanula. Type A daughter-sporocysts develop more slowly, have a greater cercarial productivity and exhibit a differential diurnal rhythm to that of Type B. Cercariae of Type A have a shorter longevity than Type B and tend to encyst in the fins rather than the gill-arches of fish intermediate hosts. The main definitive host of Type A is pike Esox lucius and, in the case of Type B, perch Perca fluviatilis. Adults of Types A and B are morphologically very similar and both species belong to the genus Rhipidocotyle.

A key to three species of larval Diphyllobothrium Cobbold, 1858 (Cestoda: Pseudophyllidea) occurring in European and North American freshwater fishes.

A key is presented to the plerocercoids of the three species of Diphyllobothrium frequently occurring in fishes of Europe and North America. The key is intended for use by both helminthologists and fish biologists. It is designed in four parts: readily visible features of gross-morphology; body-size and site data; features of gross-morphology more clearly seen under the scanning electron microscope; and features visible in histological sections.

The Lepocreadiidae (Digenea) of fishes of the north-east Atlantic: review of the genera Opechona Looss, 1907 and Prodistomum Linton, 1910

The genera Opechona Looss and Prodistomum Linton are redefined: the latter is re-established, its diagnostic character being the lack of a uroproct. Pharyngora Lebour and Neopechona Stunkard are considered synonyms of Opechona, and Acanthocolpoides Travassos, Freitas & Bührnheim is considered a synonym of Prodistomum. Opechona bacillaris (Molin) and Prodistomum [originally Distomum] polonii (Molin) n. comb. are described from the NE Atlantic Ocean. Separate revisions with keys to Opechona, Prodistomum and ‘Opechona-like’ species incertae sedis are presented. Opechona is considered to contain: O. bacillaris (type-species), O. alaskensis Ward & Fillingham, O. [originally Neopechona] cablei (Stunkard) n. comb., O. chloroscombri Nahhas & Cable, O. occidentalis Montgomery, O. parvasoma Ching sp. inq., O. pharyngodactyla Manter, O. [originally Distomum] pyriforme (Linton) n. comb. and O. sebastodis (Yamaguti). Prodistomum includes: P. gracile Linton (type-species), P. [originally Opechona] girellae (Yamaguti) n. comb., P. [originally Opechona] hynnodi (Yamaguti) n. comb., P. [originally Opechona] menidiae (Manter) n. comb., P. [originally Pharyngora] orientalis (Layman) n. comb., P. polonii and P. [originally Opechona] waltairensis (Madhavi) n. comb. Some species are considered ‘Opechona-like’ species incertae sedis: O. formiae Oshmarin, O. siddiqii Ahmad, 1986 nec 1984, O. mohsini Ahmad, O. magnatestis Gaevskaya & Kovaleva, O. vinodae Ahmad, O. travassosi Ahmad, ‘Lepidapedon’ nelsoni Gupta & Mehrotra and O. siddiqi Ahmad, 1984 nec 1986. The related genera Cephalolepidapedon Yamaguti and Clavogalea Bray and the synonymies of their constituent species are discussed, and further comments are made on related genera and misplaced species. The new combination Clavogalea [originally Stephanostomum] trachinoti (Fischthal & Thomas) is made. The taxonomy, life-history, host-specificity and zoogeography of the genera are briefly discussed.

Distribution and characterization of species of Gyrodactylus Nordmann, 1832 (Monogenea) parasitizing salmonids in the UK, and their discrimination from G. salaris Malmberg, 1957

The reported pathogenicity of the monogenean Gyrodactylus salaris Malmberg, 1957 on Atlantic Salmo salar in Norway has necessitated a national survey of salmonid sites throughout the British Isles to determine which species of the genus Gyrodactylus are resident on these hosts in British waters. Eight morphotypes were identified following examination of the opisthaptoral sclerites at both the light and scanning electron microscope level. Gyrodactylus truttae Glaser, 1974 was found on wild brown trout Salmo trutta in Scotland, England and Wales with an uncharacteristic morphotype, having long, thin marginal hooks. Two morphotypes of Gyrodactylus derjavini Mikailov, 1975 were recorded for the first time from Britain. G. caledoniensis n. sp. from Scottish S. salar is erected, based on differences in the shape and size of the marginal hooks. Two possible new species from English Salvelinus alpinus and a possible new species from Welsh S. salar and Scottish O. mykiss are described.