Host specificity, molecular phylogeny and morphological differences of Phyllodistomum pseudofolium Nybelin, 1926 and Phyllodistomum angulatum Linstow, 1907 (Trematoda: Gorgoderidae) with notes on Eurasian ruffe as final host for Phyllodistomum spp.

Abstract

BackgroundHost-specificity patterns are not well-defined for trematodes of the genus Phyllodistomum Braun, 1899. The Eurasian ruffe, Gymnocephalus cernuus L., has been recorded as a definitive host for Phyllodistomum folium (Olfers, 1816), P. angulatum Linstow, 1907 and P. megalorchis Nybelin, 1926 and as the type-host for P. pseudofolium Nybelin (1926). A wide range of other host fishes have been recorded for these species as well. All present host records have been based on light microscopy and the life-cycles of P. pseudofolium, P. angulatum and P. megalorchis are unknown. The validity of P. pseudofolium and P. megalorchis require verification. In this study, rDNA sequences generated from adult Phyllodistomum spp., as well as from larval stages developing in Pisidium amnicum Müller, were analysed to establish the real number of Phyllodistomum species utilizing G. cernuus, and to associate larvae with the corresponding adult forms.ResultsPhylogenetic analyses of adult and larval stages of Phyllodistomum spp. based on ITS2 and partial 28S rDNA data allowed the confirmation of the validity of P. pseudofolium. A macrocercous cercaria, known as Phyllodistomum sp. from P. amnicum is genetically identical to adult P. pseudofolium. Phyllodistomum megalorchis obtained from its type-host, Lota lota L., showed no genetic differences from P. angulatum parasitizing Sander lucioperca L. In our analysis, P. pseudofolium, P. angulatum and P. macrocotyle formed a highly supported clade despite the fact that these species appear to be associated with distinct patterns of first intermediate host identity and cercarial morphology. Some morphological differences between gravid specimens of P. pseudofolium and P. angulatum were observed and their SEM tegumental surface topography is described.ConclusionsThe results lead us to the perception that macroevolutionary host switching in the genus Phyllodistomum is independent of host phylogeny. This study suggests strict host-specificity (oioxeny) for P. pseudofolium using one first intermediate host species (P. amnicum) and one definitive host species (G. cernuus). Phyllodistomum megalorchis is to be regarded as a synonym of P. angulatum. The close phylogenetic relatives, P. pseudofolium and P. angulatum, can be differentiated by morphological traits, the micromorphology and tegumental surface topography of these two species is intended to provide useful data for their identification and support the use of such features as a valuable taxonomic criterion. Molecular data showed that G. cernuus is a definitive host for two species: the oioxenous P. pseudofolium and the euryxenous P. folium.

New morphological and molecular data for Xystretrum solidum (Gorgoderidae, Gorgoderinae) from Sphoeroides testudineus (Tetraodontiformes, Tetraodontidae) in Mexican waters

“…In the phylogenetic tree obtained from the 28S dataset, all members of the genus Xystretrum included in the analysis formed a well-supported clade, but without nodal support with their sister clade. A similar result has been reported in previous phylogenetic analyses carried out for similar taxa using the same gene (e.g., Cutmore et al 2013;Razo-Mendivil et al 2013;Pérez-Ponce de León et al 2015;Petkevičiūtė et al 2015;Urabe et al 2015;Stunžėnas et al 2017). Cutmore et al (2013) detected that the species of Xystretrum genus are not closely related to marine representatives of the family Gorgoderidae.…”

Phyllodistomum vaili(Plagiorchiida: Gorgoderidae) infecting Parupeneus rubescens (Perciformes: Mullidae): morphology and phylogeny

“…folium Olfers, 1816 infecting Gymnocephalus cernuus from Lithuania (19, 12%, respectively; Stunžėnas et al, 2017); P. punctati infecting Channa punctata from Ozhakkodi Wayanad, Kerala, India (7%, Jithila & Prasadan, 2018); and P. thunni Baudin-Laurencin & Richard, 1973 infecting Thunnus albacares from Gulf of Guinea (14.8%, Guidelli et al, 2018). However, it is lower than P. inecoli infecting Heterandria bimaculata from Creek at Aqua Bendita, Xico, Veracruz, Mexico (96%, Razo-Mendivil et al, 2013); P. hohhettae infecting Plectropomus leopardus from Lizard Island, Northern Great Barrier Reef (80%, Ho et al, 2014); P. vaili infecting Mulloidichthys vanicolensis from Lizard Island, Northern Great Barrier Reef (100%, Ho et al, 2014); and P. angulatum infecting S. lucioperca from Lithuania (100%; Stunžėnas et al, 2017).…”

Phyllodistomum kupermani n. sp. from the European perch, Perca fluviatilis L. (Perciformes: Percidae), and redescription of Phyllodistomum macrocotyle (Lühe, 1909) with notes on the species diversity and host specificity in the European Phyllodistomum spp. (Trematoda: Gorgoderidae)

“…in European freshwater fishes, the species composition of the genus is under scrutiny and remains controversial. Our recent studies [ 5 , 6 , 9 ] have challenged previous data on species diversity and life-cycles in this presumably well-known group of trematodes. However, there are still serious gaps in our knowledge of the genus Phyllodistomum and a number of unanswered questions concerning the validity and specificity of the nominal species and the identity of unidentified genetic lineages are still awaiting clarification.…”

“…Phyllodistomum Braun, 1899 is one of the most speciose digenean genera, comprised of species parasitizing in the urinary bladder and/or ureters of freshwater and marine fish and, more rarely, amphibians throughout the world [ 1 – 6 ], and new species descriptions continue to be published on a regular basis [ 3 , 4 , 7 , 8 ]. Species of Phyllodistomum infecting fishes of Europe have been studied for more than two centuries, starting with the description of Phyllodistomum umblae (Fabricius, 1780) (as Fasciola umblae ) from the Arctic char, Salvelinus alpinus (L.) in Norway.…”

“…(preliminary identified as P. pseudofolium Nybelin (1926)) obtained from the urinary bladder of the European perch, Perca fluviatilis L., from Volga River basin, Russia, represent distinct genetic lineage (presumably an undescribed species), resolving between P . folium (Olfers, 1816) and P. umblae clades in the ITS2 and 28S phylograms [ 6 ]. To validate the independent taxonomic status of this genetic linage, a comparative morphological study of Phyllodistomum species from P. fluviatilis was required.…”