ArticlePublisher preview available

Description of a metacercaria of a zoogonid trematode Steganoderma cf. eamiqtrema Blend and Racz, 2020 (Microphalloidea: Zoogonidae), with notes on the phylogenetic position of the genus Steganoderma Stafford, 1904, and resurrection of the subfamily Lecithostaphylinae Odhner, 1911

Authors:
Sergey G. Sokolov at Severtsov Institute of Ecology and Evolution
Sergey G. Sokolov
Sergei Shchenkov
Sergei Shchenkov
Sergei Shchenkov
  • This person is not on ResearchGate, or hasn't claimed this research yet.
Ilya I. Gordeev at Russian Federal Research Institute of Fisheries and Oceanography
Ilya I. Gordeev
T. V. Ryazanova at Kamchatka Research Institute of Fisheries and Oceanography, Petropevlovsk-Kamchatsky, Russia
T. V. Ryazanova
  • Kamchatka Research Institute of Fisheries and Oceanography, Petropevlovsk-Kamchatsky, Russia
Read publisher preview
Download citation
To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

Metacercariae of the zoogonid trematode Steganoderma cf. eamiqtrema ex crab Chionoecetes bairdi caught in the Sea of Okhotsk were described using morphological and molecular-genetic (ITS2 region, 28S rRNA and nd1 genes) data. These are the first molecular-genetic data for the genus Steganoderma. The studied trematodes differed from S. eamiqtrema in having a much larger body size. The phylogenetic analysis based on the 28S rRNA gene supported neither the current taxonomic hypothesis that Steganoderma belongs to the subfamily Lepidophyllinae nor the earlier views that the Steganodermatinae and the Lecithostaphylinae are synonymous. The topology of the phylogenetic tree shows that the Steganodermatinae and the Lecithostaphylinae are independent subfamilies. However, morphological differences between them are obscure. Until morphological evidence for the Steganodermatinae is found, we propose to distinguish the subfamily Lepidophyllinae sensu stricto with the genera Lepidophyllus and Urinatrema, and the subfamily Lecithostaphylinae sensu lato uniting all the other former lepidophyllines. Thus, for now, we propose to consider the Steganodermatinae as a conditional synonym for Lecithostaphylinae sensu lato.
Figures - available from: Parasitology Research
This content is subject to copyright. Terms and conditions apply.
A preview of this full-text is provided by Springer Nature.
Learn more
Content available from Parasitology Research
This content is subject to copyright. Terms and conditions apply.
GENETICS, EVOLUTION, AND PHYLOGENY - ORIGINAL PAPER
Description of a metacercaria of a zoogonid trematode
Steganoderma cf. eamiqtrema Blend and Racz, 2020
(Microphalloidea: Zoogonidae), with notes on the phylogenetic
position of the genus Steganoderma Stafford, 1904, and resurrection
of the subfamily Lecithostaphylinae Odhner, 1911
Sergey Sokolov
1
&Sergey Shchenkov
2
&Ilya Gordeev
3,4
&Tatyana Ryazanova
5
Received: 6 December 2020 /Accepted: 4 April 2021
#The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2021
Abstract
Metacercariae of the zoogonid trematode Steganoderma cf. eamiqtrema ex crab Chionoecetes bairdi caught in the Sea of
Okhotsk were described using morphological and molecular-genetic (ITS2 region, 28S rRNA and nd1 genes) data. These are
the first molecular-genetic data for the genus Steganoderma. The studied trematodes differed from S. eamiqtrema in having a
much larger body size. The phylogenetic analysis based on the 28S rRNA gene supported neither the current taxonomic
hypothesis that Steganoderma belongs to the subfamily Lepidophyllinae nor the earlier views that the Steganodermatinae and
the Lecithostaphylinae are synonymous. The topology of the phylogenetic tree shows that the Steganodermatinae and the
Lecithostaphylinae are independent subfamilies. However, morphological differences between them are obscure. Until morpho-
logical evidence for the Steganodermatinae is found, we propose to distinguish the subfamily Lepidophyllinae sensu stricto with
the genera Lepidophyllus and Urinatrema, and the subfamily Lecithostaphylinae sensu lato uniting all the other former
lepidophyllines. Thus, for now, we propose to consider the Steganodermatinae as a conditional synonym for
Lecithostaphylinae sensu lato.
Keywords Chionoecetes bairdi .Steganodermatinae .Lepidophyllinae .The Sea of Okhotsk .28S rRNA gene .Metacercaria .
Steganoderma cf. eamiqtrema
Introduction
The family Zoogonidae Odhner, 1902, comprises microphalloid
trematodes parasitizing marine and, more rarely, freshwater fish
(Bray 2008). According to the current taxonomic model, the
zoogonid genera are grouped into three subfamilies: the
Zoogoninae Odhner, 1902, the Cephaloporinae Yamaguti 1934,
and the Lepidophyllinae Stossich, 1904 (Cutmore et al. 2014;
Blend et al. 2020). The establishment of these subfamilies is
based on morphological evidence (Bray 1987,2008), with only
some molecular data being taken into account (Cutmore et al.
2014).
AccordingtoBlendetal.(2020), the list of synonyms of the
Lepidophyllinae includes the names Hudsoniinae Campbell,
1975, Lecithostaphylinae Odhner 1911, Pseudopalaeorchiinae
Yamaguti 1971, and Steganodermatinae Yamaguti 1934.The
subfamily Lecithostaphylinae was erected by Odhner (1911)
simultaneously with the description of the genus
Lecithostaphylus Odhner 1911. Yamaguti (1934) synonymized
Lecithostaphylus with Steganoderma Stafford, 1904, and
replaced the name of the subfamily Lecithostaphylinae with
the Steganodermatinae Yamaguti 1934. However, Fantham
Handling Editor: Julia Walochnik
*Ilya Gordeev
gordeev_ilya@bk.ru
1
A.N. Severtsov Institute of Ecology and Evolution, Moscow, Russia
2
Department of Invertebrate Zoology, St. Petersburg State University,
St. Petersburg, Russia
3
Russian Federal Research Institute of Fisheries and Oceanography,
Moscow, Russia
4
Lomonosov Moscow State University, Moscow, Russia
5
Kamchatka branch of Russian Federal Research Institute of Fisheries
and Oceanography, Petropavlovsk-Kamchatsky, Russia
https://doi.org/10.1007/s00436-021-07151-6
/ Published online: 9 April 2021
Parasitology Research (2021) 120:1669–1676
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... The family Zoogonidae Odhner, 1902 is one of the taxonomically problematic groups of trematodes, which was periodically revised on the basis of the morphological and biological features of its representatives (Bray and Gibson, 1986;Bray, 1986, Bray, 2008, Blend et al., 2020Sokolov et al., 2021a, Kremnev et al., 2023. Bray (2008) recognised two subfamilies within the family Zoogonidae: Zoogoninae Odhner, 1902 andLepidophyllinae Stossich, 1903. ...
... Bray (2008) recognised two subfamilies within the family Zoogonidae: Zoogoninae Odhner, 1902 andLepidophyllinae Stossich, 1903. Recently, the subfamilies Cephaloporinae Yamaguti, 1934 andLecithostaphyllinae Odhner, 1911 were resurrected within Zoogonidae (Blend et al., 2020;Sokolov et al., 2021a). According to Bray (2008), the subfamily Zoogoninae comprises nine genera of intestinal trematodes of marine, anadromous, and amphidromic fishes. ...
... Kremnev et al., 2023). Results of several phylogenetic studies based on molecular data show that Zoogonodae is non-monophyletic, but formed strongly supported monophyly with representatives of Faustulidae; the problem actively discussed and still unresolved (Hall et al., 1999;Sun et al., 2014;Sokolov et al., 2021a;2021b). ...
Morphological and molecular data on Pseudozoogonoides ugui Shimazu, 1974 (Digenea: Microphalloidea: Zoogonidae) ex Pseudaspius hakonensis (Günther, 1877) and taxonomic problems in Zoogoninae genera
Article
  • Apr 2024
  • J HELMINTHOL
New morphological and molecular data were generated for trematodes recovered from the intestines of the fish Pseudaspius hakonensis from two locations in the south of the Russian Far East. Morphologically, these trematodes are identical to Pseudozoogonoides ugui (Microphalloidea: Zoogonidae) from Japan. According to results of phylogenetic analysis based on 28S rDNA sequence data, P. ugui was closely related to Zoogonoides viviparus , and P. subaequiporus appears as a sister taxon to these two species. Genetic distance values, calculated based on both 28S rDNA and ITS2 rDNA, between P. ugui and Z. viviparus represents an interspecific differentiation level. Our results have an ambiguous explanation, indicating that the implication of the presence of one or two compact vitellarial aggregations for the differentiation of Zoogonoides and Pseudozoogonoides should be reconsidered or that our results open up the question of the taxonomical status of trematodes previously denoted as Z. viviparus and P. subaequiporus.
View
... Bray (2008 considered Lecithostaphylus as a valid genus of the subfamily Lepidophyllinae Stossich, 1904. Later, several complex studies indicated that Lecithostaphylus was phylogenetically distant from the genus Lepidophyllum Odhner, 1902 and could be separated into a distinct subfamily Lecithostaphylinae Odhner, 1911(Cabañas-Granillo et al., 2020Sokolov et al., 2021a;2021b). On the basis of molecular-based species clustering, Sokolov et al. (2021b) resurrected the subfamily Lecithostaphylinae and provided a diagnosis of Lecithostaphylinae sensu lato, including the genera Lecithostaphylus (as the type genus), Deretrema Linton, 1910, Proctophantases Odhner, 1911and Steganoderma Stafford, 1904. ...
... Later, several complex studies indicated that Lecithostaphylus was phylogenetically distant from the genus Lepidophyllum Odhner, 1902 and could be separated into a distinct subfamily Lecithostaphylinae Odhner, 1911(Cabañas-Granillo et al., 2020Sokolov et al., 2021a;2021b). On the basis of molecular-based species clustering, Sokolov et al. (2021b) resurrected the subfamily Lecithostaphylinae and provided a diagnosis of Lecithostaphylinae sensu lato, including the genera Lecithostaphylus (as the type genus), Deretrema Linton, 1910, Proctophantases Odhner, 1911and Steganoderma Stafford, 1904. ...
... Steganoderma eamiqtrema has high p-distance values, 20.44 ± 1.21%-23.68 ± 1.23%, as compared with species of Lecithostaphylinae sensu stricto by 28S rDNA sequence data, and the phylogenetic relationships of this species are poorly supported in the study by Sokolov et al. (2021b). Moreover, in our study, S. eamiqtrema (Zoogonidae) was sister to [Lecithostapyhllinae + Zoogoninae + Faustulidae (Antorchis pomacanthi, Trigonocryptus conus and Bacciger lesteri)] clade on both ML and BI trees with a high support (figs 2 and 3). ...
New trematode species Lecithostaphylus halongi n. sp. (Zoogonidae, Microphalloidea) and Gymnotergestia strongyluri n. sp. (Fellodistomidae, Gymnophalloidea) from beloniform fishes in Vietnam
Article
  • Mar 2022
In this study we described two new trematode species, Lecithostaphylus halongi n. sp. (Zoogonidae, Lecithostaphylinae) and Gymnotergestia strongyluri n. sp. (Fellodistomidae, Tergestiinae), on the basis of morphological and molecular data. Adult worms of these two species were collected from, respectively, Hemiramphus spp. (Hemiramphidae) and Strongylura strongylura (Belonidae) caught in the coastal waters of Vietnam. Adult worms of L . halongi n. sp. are morphologically close to Lecithostaphylus gibsoni Cribb, Bray & Barker, 1992 ex Abudefduf whitleyi from Heron Island and Lecithostaphylus depauperati Yamaguti, 1970 ex Hemiramphus depauperatus from Hawaii, but differ from these species in having a larger cirrus sac and a different arrangement of vitelline fields. They also differ from Lecithostaphylus brayi Cabañas-Granillo, Solórzano-García, Mendoza-Garfias & Pérez-Ponce de León, 2020 in the 28S ribosomal DNA (rDNA) sequence data at the interspecific level. Adult worms of G . strongyluri n. sp. ex S . strongylura are morphologically similar to Gymnotergestia chaetodipteri , the only previously known species of this genus, described from Chaetodipterus faber in Jamaica. The new species differs from G . chaetodipteri in body shape, testicular arrangement and the size of the pharynx and eggs. The 28S rDNA-based phylogenetic analysis indicates that G . strongyluri n. sp. is closely related to Tergestia spp., rendering Tergestia paraphyletic. Genetic divergence values between G . strongyluri n. sp. and Tergestia spp. are similar to those among species in the genera Tergestia , Steringophorus and Proctoeces . Our molecular results indicate that G . strongyluri n. sp. and Tergestia spp. may belong the same genus, but additional molecular data are needed for the final conclusion.
View
... Similarly to previous studies [37][38][39][40], the Zoogonidae was resolved within the Microphalloidea as a well-supported clade, though containing some members of the family Faustulidae ( Figure 2). The latter is known to be polyphyletic as several faustulid species fall into the superfamily Gymnophalloidea [41][42][43], thus we place this family name into the quotation marks. ...
... Monophyly of the latter was poorly supported. The former Lepidophyllinae was resolved as highly paraphyletic, and the Zoogoninae was inferred as the closest relative of the "faustulids", similarly to previous studies [37][38][39][40][41][42][43]. Other reported hosts: 20 fish species (summarized in [44]). ...
No Tail No Fail: Life Cycles of the Zoogonidae (Digenea)
Article
Full-text available
  • Jan 2023
  • Diversity
The Zoogonidae is the only digenean family where known cercariae lack the tail but actively search for the second intermediate host. However, the data on the zoogonid life cycles are scarce. In the present study, we elucidated and verified life cycles of the Zoogonidae from the White Sea. Using rDNA data, we showed that Pseudozoogonoides subaequiporus utilizes gastropods from the family Buccinidae as the first intermediate host and protobranch bivalves as the second one. This life cycle can be facultatively truncated: some cercariae of P. subaequiporus encyst within the daughter sporocysts. Molecular data also confirmed previous hypotheses on Zoogonoides viviapus life cycle with buccinid gastropods acting as the first intermediate hosts, and annelids and bivalves as the second intermediate hosts. We demonstrated the presence of short tail primordium in the developing cercariae of both species. Based on the reviewed and our own data, we hypothesize that the emergence of tailless cercariae in the evolution of the Zoogonidae is linked to the switch to non-arthropod second intermediate hosts, and that it possibly happened only in the subfamily Zoogoninae. Basally branching zoogonids have retained the ancestral second intermediate host and might have also retained the tail.
View
... However, Bray [3,5] moved Anarhichotrema into the Zoogonidae based on the understanding that lissorchiids did not typically parasitise marine fish. According to the current zoogonid concept, Anarhichotrema is affiliated to the Lecithostaphylinae Odhner, 1911 sensu lato [6]. However, the lack of molecular genetic data for this genus significantly complicates evaluation of its phylogenetic position. ...
Phylogenetic Evidence for the Lissorchiid Concept of the Genus Anarhichotrema Shimazu, 1973 (Trematoda, Digenea)
Article
Full-text available
  • Feb 2022
  • Diversity
Anarhichotrema Shimazu, 1973 is a monotypic digenean genus, with the type- and only species, Anarhichotrema ochotense Shimazu, 1973, known to infect North Pacific fishes. This genus was originally described as a member of the Lissorchiidae (Monorchioidea) and later moved to the Zoogonidae (Microphalloidea). Its exact phylogenetic position has remained unresolved due to the lack of molecular data. In this study, we isolated specimens of A. ochotense from the Bering wolffish, Anarhichas orientalis Pallas, 1814 caught in the Sea of Okhotsk, described them morphologically and performed a molecular phylogenetic analysis of their nuclear 18S and 28S rDNA regions. The specimens examined in our study generally corresponded to previous morphological descriptions of A. ochotense but were noticeably smaller, possibly due to the crowding effect. The phylogenetic analysis placed Anarhichotrema within the Lissorchiidae as a sister taxon to the group comprising freshwater lissorchiids. Thus, we restore Anarhichotrema to the Lissorchiidae, as originally assigne.
View
View
Steganoderma Stafford, 1904 (Digenea: Zoogonidae: Lepidophyllinae) from Two Species of Rockfishes from Deep Waters off Oregon Including a New Species and an Updated Key to Species of This Genus
Article
Full-text available
  • Oct 2020
Steganoderma eamiqtrema n. sp. and a single unidentified specimen of Steganoderma Stafford, 1904 (Zoogonidae: Lepidophyllinae) obtained from the intestine of the greenstriped rockfish, Sebastes elongatus Ayres, 1859, and the flag rockfish, Sebastes rubrivinctus (Jordan and Gilbert, 1880) (Scorpaeniformes: Sebastidae), collected from 190–200 m depths off Oregon, USA, are described. The new species is distinguished from its seven other congeners by a diagnostic combination of morphological features including an elongate oval to spindle-shaped body, a clavate to comma-shaped cirrus pouch located in the forebody and hindbody, a bipartite seminal vesicle, a bifurcal or just post-bifurcal genital pore, a larger ventral than oral sucker, and a smooth testes and ovary with a relatively small distance between them. We present an updated key to the eight species now in Steganoderma and provide a list of parasites known from Se. elongatus and Se. rubrivinctus. The discovery of S. eamiqtrema in Se. elongatus represents the second species of zoogonid known from this host, and the finding of Steganoderma sp. in Se. rubrivinctus represents the first report of a digenean from this host species. A detailed discussion also is given of the type species, S. formosum Stafford, 1904, and questions are raised as to whether this species has a worldwide distribution and infects such a wide variety of fish hosts. We present evidence including variation we observed in redescriptions of the type species, query the implausible idea that there could be gene flow between conspecific helminths geographically separated in the North Atlantic and North Pacific Oceans over such a vast geological period, and offer the possibility that some prior reports of S. formosum may, indeed, be S. eamiqtrema; all of which suggests S. formosum sensu lato may be part of a species complex and not the same worldwide species. Steganoderma is represented in the deep sea by S. eamiqtrema, S. formosum, and Steganoderma sp., and limited speculation is given as to the host specificity of this genus and life history strategies of the new species in deeper waters. Finally, molecular studies of species of Steganoderma are sorely needed (i.e., there is no DNA sequence data currently available in GenBank for any species of this genus), and we suspect that with further molecular, morphological, and life history work, this genus will be taxonomically divided up.
View
Gaharitrema droneni n. gen., n. sp. (Digenea: Zoogonidae) from the Pudgy Cuskeel, Spectrunculus grandis (Ophidiiformes: Ophidiidae), from Deep Waters Off Oregon, with Updated Keys to Zoogonid Subfamilies and Genera
Article
Full-text available
  • Mar 2020
Gaharitrema droneni n. gen., n. sp. (Digenea: Zoogonidae: Lepidophyllinae) is described from the intestine of the pudgy cuskeel, Spectrunculus grandis (Gu¨ nther, 1877) (Ophidiiformes: Ophidiidae), collected at 2,800 m depth from the northeastern Pacific Ocean off Oregon. The new genus is distinguished from Brachyenteron Manter, 1934 and Steganoderma Stafford, 1904, the 2 closest lepidophylline genera, and from 4 other zoogonid genera erected since 2007, the last major revision of the family, by a combination of diagnostic features including a pyriform or spindle-shaped body, smooth testes and ovary, narrow ceca that reach with the vitellarium into the hindbody, an unspecialized ventral sucker, non-filamented eggs, a claviform cirrus pouch, and an unpocketed ejaculatory duct and metraterm, and the new genus lacks circumoral spines. We present updated keys to the 3 subfamilies of the Zoogonidae Odhner, 1902, as well as to the genera of the Cephaloporinae Yamaguti, 1934 and the Lepidophyllinae Stossich, 1903. A listing of the parasites known from S. grandis also is presented. This study documents the third family of digeneans (Zoogonidae) known to parasitize S. grandis, and it is a new host record (i.e., the first zoogonid reported from this host species). We discuss the relatively impressive presence of the Zoogonidae and their hosts within the deep sea. Specifically, of the 35 genera we recognize within this digenean family, 14 (40%) have deep-sea representatives. At least 37 species within 27 genera and 19 families within 11 orders of deep-sea fish are known to harbor zoogonids. Furthermore, of the 37 known deep-sea fish species parasitized by zoogonids, only 5 (13.5%) harbor 2 or more zoogonid species; the remaining 32 (86.5%) harbor only 1 parasite species each, indicating strong host specificity. Finally, the dietary ecology of S. grandis is presented, allowing us to speculate that Gaharitrema droneni may be utilizing gastropods and polychaetes as well as S. grandis to complete its life cycle in the deep sea.
View
Posterior Summarization in Bayesian Phylogenetics Using Tracer 1.7
Article
Full-text available
  • Apr 2018
  • SYST BIOL
Bayesian inference of phylogeny using Markov chain Monte Carlo (MCMC) (Drummond et al., 2002; Mau et al., 1999; Rannala and Yang, 1996) flourishes as a popular approach to uncover the evolutionary relationships among taxa, such as genes, genomes, individuals or species. MCMC approaches generate samples of model parameter values - including the phylogenetic tree -drawn from their posterior distribution given molecular sequence data and a selection of evolutionary models. Visualising, tabulating and marginalising these samples is critical for approximating the posterior quantities of interest that one reports as the outcome of a Bayesian phylogenetic analysis. To facilitate this task, we have developed the Tracer (version 1.7) software package to process MCMC trace files containing parameter samples and to interactively explore the high-dimensional posterior distribution. Tracer works automatically with sample output from BEAST (Drummond et al., 2012), BEAST2 (Bouckaert et al., 2014), LAMARC (Kuhner, 2006), Migrate (Beerli, 2006), MrBayes (Ronquist et al., 2012), RevBayes (Höhna et al., 2016) and possibly other MCMC programs from other domains.
View
Microphallus ochotensis sp. nov. (Digenea, Microphallidae) and relative merits of two-host microphallid life cycles
Article
Full-text available
  • Apr 2018
  • Parasitol Res
A new digenean species, Microphallus ochotensis sp. nov., was described from the intestine of Pacific eiders (Somateria mollissima v-nigrum) from the north of the Sea of Okhotsk. It differs from other microphallids in the structure of the metraterm, which consists of two distinct parts: a sac with spicule-like structures and a short muscular duct opening into the genital atrium. Mi. ochotensis forms a monophyletic clade together with other congeneric species in phylograms derived from the 28S and ITS2 rRNA gene. Its dixenous life cycle was elucidated with the use of the same molecular markers. Encysted metacercariae infective for birds develop inside sporocysts in the first intermediate host, an intertidal mollusc Falsicingula kurilensis. The morphology of metacercariae and adults was described with an emphasis on the structure of terminal genitalia. Considering that Falsicingula occurs at the Pacific coast of North America and that the Pacific eider is capable of trans-continental flights, the distribution of Mi. ochotensis might span the Pacific coast of Alaska and Canada. The range of its final hosts may presumably include other benthos-feeding marine ducks as well as shorebirds. We suggest that a broad occurrence of two-host life cycles in microphallids is associated with parasitism in birds migrating along sea coasts. The chances that migrating birds would stop at a site where both first and second intermediate hosts occur are relatively low. The presence of a single molluscan host in the life cycle increases the probability of transmission. The shared link: http://rdcu.be/Gdkm
View
A new species of Lecithostaphylus Odhner, 1911 (Trematoda: Zoogonidae) from the Pacific needlefish, Tylosurus pacificus, off the Pacific coast of Mexico, with a molecular assessment of the phylogenetic position of this genus within the family
Article
  • Sep 2020
A new species of Lecithostaphylus Odhner, 1911 (Zoogonidae) is described from the Pacific agujon needlefish, Tylosurus pacificus (Steindachner) (Belonidae), from two localities off the Pacific coast of Mexico. Morphologically, the new species agrees with the diagnosis of the genus Lecithostaphylus. Lecithostaphylus brayi sp. nov. differs from other congeneric species by a combination of morphological traits, including the overall body size, anterior and posterior extension of the vitelline follicles in the hindbody, and the presence/absence of papilla-like denticles on internal surface of ventral sucker. Lecithostaphylus brayi sp. nov. most closely resembles L. retroflexus (Molin, 1859), Odhner, 1911 and Lecithostaphylus tylosuri Châari, Derbel & Neifar, 2013 from Mediterranean needlefishes and Lecithostaphylus nitens (Linton, 1898) Linton, 1940 from needlefishes in multiple marine ecoregions; however, it can be distinguished by subtle morphological differences, host association, and geographical distribution. The new species will require further verification through a more detailed morphological study of L. nitens and, ideally, molecular data for L. nitens, L. retorflexus, and L. tylosuri. Newly generated 28S rDNA sequences allowed a phylogenetic assessment of the genus and show that Lecithostaphylus clades within the Zoogonidae, sister to the genera Deretrema Linton, 1910 + Proctophantastes Odhner, 1911, although the family Zoogonidae is not resolved as monophyletic. The inclusion of more representative genera in the molecular phylogenetic analysis will be needed to generate a more robust classification scheme for the Zoogonidae, and to discuss host specificity patterns for members of the family.
View
A new species of Atriophallophorus Deblock & Rosé, 1964 (Trematoda: Microphallidae) described from in vitro -grown adults and metacercariae from Potamopyrgus antipodarum (Gray, 1843) (Mollusca: Tateidae)
Article
  • Jan 2020
The adult and metacercaria life stages of a new species of the microphallid genus Atriophallophorus Deblock & Rosé, 1964 are described from specimens collected at Lake Alexandrina (South Island, New Zealand). In addition to molecular analyses of ribosomal and mitochondrial genes, metacercariae of Atriophallophorus winterbourni n. sp. from the snail host Potamopyrgus antipodarum (Gray) were grown in vitro to characterize internal and external morphology of adults using light and scanning electron microscopy and histological techniques. Atriophallophorus winterbourni n. sp. is readily distinguishable from Atriophallophorus coxiellae Smith, 1973 by having a different structure of the prostatic chamber, sub-circular and dorsal to genital atrium, rather than cylindrical, fibrous, elongate and placed between the seminal vesicle and the genital atrium. The new species is most similar to Atriophallophorus minutus (Price, 1934) with regards to the prostatic chamber and the morphometric data, but possesses elongate-oval testes and subtriangular ovary rather than oval and transversely oval in A. minutus . Phylogenetic analyses including sequence data for A. winterbourni n. sp. suggested a congeneric relationship of the new species to a hitherto undescribed metacercariae reported from Australia, both forming a strongly supported clade closely related to Microphallus and Levinseniella . In addition, we provide an amended diagnosis of Atriophallophorus to accommodate the new species and confirm the sinistral interruption of the outer rim of the ventral sucker caused by the protrusion of the dextral parietal atrial scale at the base of the phallus.
View
Testing the higher-level phylogenetic classification of Digenea (Platyhelminthes, Trematoda) based on nuclear rDNA sequences before entering the age of the ‘next-generation’ Tree of Life
Article
  • May 2019
Digenea Carus, 1863 represent a highly diverse group of parasitic platyhelminths that infect all major vertebrate groups as definitive hosts. Morphology is the cornerstone of digenean systematics, but molecular markers have been instrumental in searching for a stable classification system of the subclass and in establishing more accurate species limits. The first comprehensive molecular phylogenetic tree of Digenea published in 2003 used two nuclear rRNA genes (ssrDNA = 18S rDNA and lsrDNA = 28S rDNA) and was based on 163 taxa representing 77 nominal families, resulting in a widely accepted phylogenetic classification. The genetic library for the 28S rRNA gene has increased steadily over the last 15 years because this marker possesses a strong phylogenetic signal to resolve sister-group relationships among species and to infer phylogenetic relationships at higher levels of the taxonomic hierarchy. Here, we have updated the database of 18S and 28S rRNA genes until December 2017, we have added newly generated 28S rDNA sequences and we have reassessed phylogenetic relationships to test the current higher-level classification of digeneans (at the subordinal and subfamilial levels). The new dataset consisted of 1077 digenean taxa allocated to 106 nominal families for 28S and 419 taxa in 98 families for 18S. Overall, the results were consistent with previous higher-level classification schemes, and most superfamilies and suborders were recovered as monophyletic assemblages. With the advancement of next-generation sequencing (NGS) technologies, new phylogenetic hypotheses from complete mitochondrial genomes have been proposed, although their power to resolve deep levels of trees remains controversial. Since data from NGS methods are replacing other widely used markers for phylogenetic analyses, it is timely to reassess the phylogenetic relationships of digeneans with conventional nuclear rRNA genes, and to use the new analysis to test the performance of genomic information gathered from NGS, e.g. mitogenomes, to infer higher-level relationships of this group of parasitic platyhelminths.
View
ape 5.0: an environment for modern phylogenetics and evolutionary analyses in R
Article
  • Jul 2018
  • BIOINFORMATICS
After more than fifteen years of existence, the R package ape has continuously grown its contents, and has been used by a growing community of users. The release of version 5.0 has marked a leap towards a modern software for evolutionary analyses. Efforts have been put to improve efficiency, flexibility, support for 'big data' (R's long vectors), ease of use, and quality check before a new release. These changes will hopefully make ape a useful software for the study of biodiversity and evolution in a context of increasing data quantity. Availability: ape is distributed through the Comprehensive R Archive Network: http://cran.r-project.org/package=apeFurther information may be found athttp://ape-package.ird.fr/.
View
View
The systematic position and structure of the genus Leyogonimus Ginetsinskaya, 1948 (Platyhelminthes: Digenea) with comments on the taxonomy of the superfamily Microphalloidea Ward, 1901
Article
  • Sep 2017
The systematic position, phylogenetic relationships and composition of the genus Leyogonimus Ginetsinskaya, 1948 have always been uncertain. In the present study, we investigate the taxonomic position and phylogenetic relationships between the type-species L. polyoon (Linstow, 1887) and L. postgonoporus (Neiland, 1951) (previously classified as Macyella), based on newly obtained partial sequences of the nuclear large ribosomal subunit DNA. To test some of the previously proposed systematic arrangements, we have also sequenced specimens of Stomylotrema vicarium Braun, 1901 and Phaneropsolus sp. Our results clearly demonstrate that both L. polyoon and L. postgonoporus belong to the family Pleurogenidae Looss, 1899 within the superfamily Microphalloidea. Thus, the Leyogonimidae Dollfus, 1951 should be recognized as a synonym of the Pleurogenidae. Leyogonimus polyoon clearly constitutes a separate, sister branch to the clade consisting of Collyricloides massanae Vaucher, 1969 and L. postgonoporus. Based on these results, we resurrect the genus Macyella Neiland, 1951 with type-species M. postgonoporus. Besides, Collyricloides Vaucher, 1968 is synonymized with Macyella resulting in new combination Macyella massanae (Vaucher, 1968) comb. nov. Molecular phylogenetic analysis has demonstrated the lack of a close phylogenetic relationships between Stomylotema vicarium and Leyogonimus previously placed by several authors into the family Stomylotrematidae Poche, 1925. The status of the Phaneropsolidae Mehra, 1935 as independent family was confirmed with the addition of the newly sequenced Phaneropsolus sp. from China.
View