Rodney A. Bray

Phylogeny and classification of the Digenea (Platyhelminthes: Trematoda).

Complete small subunit ribosomal RNA gene (ssrDNA) and partial (D1-D3) large subunit ribosomal RNA gene (lsrDNA) sequences were used to estimate the phylogeny of the Digenea via maximum parsimony and Bayesian inference. Here we contribute 80 new ssrDNA and 124 new lsrDNA sequences. Fully complementary data sets of the two genes were assembled from newly generated and previously published sequences and comprised 163 digenean taxa representing 77 nominal families and seven aspidogastrean outgroup taxa representing three families. Analyses were conducted on the genes independently as well as combined and separate analyses including only the higher plagiorchiidan taxa were performed using a reduced-taxon alignment including additional characters that could not be otherwise unambiguously aligned. The combined data analyses yielded the most strongly supported results and differences between the two methods of analysis were primarily in their degree of resolution. The Bayesian analysis including all taxa and characters, and incorporating a model of nucleotide substitution (general-time-reversible with among-site rate heterogeneity), was considered the best estimate of the phylogeny and was used to evaluate their classification and evolution. In broad terms, the Digenea forms a dichotomy that is split between a lineage leading to the Brachylaimoidea, Diplostomoidea and Schistosomatoidea (collectively the Diplostomida nomen novum (nom. nov.)) and the remainder of the Digenea (the Plagiorchiida), in which the Bivesiculata nom. nov. and Transversotremata nom. nov. form the two most basal lineages, followed by the Hemiurata. The remainder of the Plagiorchiida forms a large number of independent lineages leading to the crown clade Xiphidiata nom. nov. that comprises the Allocreadioidea, Gorgoderoidea, Microphalloidea and Plagiorchioidea, which are united by the presence of a penetrating stylet in their cercariae. Although a majority of families and to a lesser degree, superfamilies are supported as currently defined, the traditional divisions of the Echinostomida, Plagiorchiida and Strigeida were found to comprise non-natural assemblages. Therefore, the membership of established higher taxa are emended, new taxa erected and a revised, phylogenetically based classification proposed and discussed in light of ontogeny, morphology and taxonomic history.

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

A DNA-based demonstration of a three-host life-cycle for the Bivesiculidae (Platyhelminthes : Digenea)

Immature bivesiculid trematodes collected from the intestine of Thlalassoma lunare (Labridae) are shown to be morphologically consistent with adults of Bivesicula claviformis from Epinephelus fasciatus (Serranidae). In addition, the immature bivesiculids have the same sequence for the second internal transcribed spacer of the ribosomal DNA. Comparison with three other species of Bivesiculidae showed differences of between 23% and 30%. These results show that bivesiculids may have three-host life-cycles in addition to the two-host life-cycles that have been demonstrated previously. The three-host life-cycle enables bivesiculids to infect large carnivorous fishes.

Gut wash, body soak, blender and heat-fixation: approaches to the effective collection, fixation and preservation of trematodes of fishes.

Advice is offered on some effective methods for collecting and preserving trematodes from fishes for taxonomy and systematics. Emphasis is placed on obtaining high-quality specimens that have reliable data and that are amenable to study by both morphological and molecular approaches. We emphasise the importance of the freshness of the host specimen, the reliability of its provenance and the labelling of the specimens. For the collecting itself, we recommend a ‘gut-wash’ approach for gastro-intestinal species and specific searches for atypical taxa such as didymozoids, aporocotylids, Saturnius Manter, 1969 and transversotrematids. For metacercariae, we recommend a ‘blender’ approach to release parasites from host tissues. For fixation, we argue in favour of heat-killing in fluid at close to boiling temperature. We recommend against flattening as a routine procedure for collecting specimens for morphology. Preservation for morphological study is best in formalin or alcohol, and alcohol works well for molecular samples. The importance of reliable labelling and the deposition of specimens in museums is emphasised.

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.

The phylogeny of the Lepocreadioidea (Platyhelminthes, Digenea) inferred from nuclear and mitochondrial genes: Implications for their systematics and evolution

The phylogenetic relationships of representative species of the superfamily Lepocreadioidea were assessed using partial lsrDNA and nad1 sequences. Forty-two members of the family Lepocreadiidae, six putative members of the Enenteridae, six gyliauchenid species and one Gorgocephalidae, were studied along with 22 species representing 8 families. The Lepocreadioidea is found to be monophyletic, except for the two species of the putative enenterid genus Cadenatella, which are found to be only distantly related to the lepocreadioids. The Lepocreadioidea is formed of five clades in a polytomy, the Gorgocephalidae, a clade containing the Enenteridae and Gyliauchenidae, a small clade of atypical lepocreadiines and the deep-sea lepidapedine lepocreadiids, a small clade consisting of a freshwater form and a group of shallow-water putative lepidapedines and the final clade includes the remaining lepocreadiids. Thus, the generally accepted concept of the Lepocreadiidae is polyphyletic. The Enenteridae (minus Cadenatella) and the Gyliauchenidae are jointly and individually monophyletic, and are sister groups. The nad1 gene on its own places a deep-sea lepocreadiine with the deep-sea lepidapedines, whereas lsrDNA, combined sequences and morphology place this deep-sea lepocreadiine within a group of typical lepocreadiids. It could not be demonstrated that a significant proportion of sites in the nad1 gene evolved under positive selection; this anomalous relationship therefore remains unexplained. Most deep-sea species are in a monophyletic group, a few of which also occur in shallow waters, retaining some characters of the deep-sea clade. Many lepocreadioid species infect herbivorous fish, and it may be that the recently discovered life-cycle involving a bivalve first intermediate host and metacercariae encysted on vegetation is a common life-cycle pattern. The host relationships show no indication of co-speciation, although the host-spectrums exhibited are not random, with related worms tending to utilize related hosts. There are, however, many exceptions. Morphology is found to be of limited value in indicating higher level relationships. For example, even with the benefit of hindsight the gyliauchenids show little morphological similarity to their sister group, the Enenteridae.

Digeneans of the family Opecoelidae Ozaki, 1925 from the southern Great Barrier Reef, including a new genus and three new species

The following Digenea are described, recorded or figured from Heron Island and Fairfax Island in the southern Great Barrier Reef, off Queensland, northeastern Australia. Opegaster ditrematis from Apogon sp., Allopodocotyle epinepheli from Epinephelus quoyanus, Podocotyloides stenometra from Chaetodon rainfordi and C. plebius, Cainocreadium epinepheli from E. quoyanus and E. merra, Pacificreadium serrani (syn: Hamacreadium ghardagense) from Plectropomus leopardus, Hamacreadium mutabile (with 10 new synonyms) from Lutjanus amabilis, Helicometra fasciata from E. fasciata and E. merra, Macvicaria macassarensis n. comb. from Lethrinus chrysostomus, M. heronensis sp. nov. from L. chrysostomus and Gymnocranius bitorquatus, Pseudoplagioporus interruptus from L. chrysostomus, Orthodena tropica from L. chrysostomus, Propycnadenoides philippinensis (syn: Labrifer gymnocrani) from G. bitorquatus, Neochoanostoma avidabira gen, et sp. nov. from G. bitorquatus, N. bariadiva sp. nov. from G. bitorquatus. Plagioporus japo...

Digenean parasites of deep-sea teleosts: a review and case studies of intrageneric phylogenies.

Studies on the digenean parasites of deep-sea (> 200 m depth) teleosts are reviewed and two case study generic phylogenies are presented based on LSU rDNA and ND1 mtDNA sequences. The phylogeny of the lepocreadiid genus Lepidapedon, the most common deep-sea digenean genus, is not clearly resolved as the two gene trees are not compatible. It can be inferred, however, that the genus has radiated in the deeper waters off the continental shelf, mainly in fishes of the gadiform family Macrouridae. Steringophorus, a fellodistomid genus, is better resolved. In this case a deep-sea radiation is also indicated, but the pattern of host-specificity is not clear, with evidence of much host-switching. Results of studies of the parasites of the macrourid fish Coryphaenoides (Nematonurus) armatus from various depths have reinforced recent views on the lack of zoned depth-related communities in the deep-sea. The diversity of deep-sea digeneans is relatively low with only 18 families (of about 60) reported. Little, or nothing, is known from most deep-sea areas and nothing from trenches and mid-ocean ridge systems.

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.