A Phylogenetic Re-Evaluation of the Stenakrine Opecoelids (Trematoda, Digenea: Opecoeloidea) with Some Taxonomic Novelties

Abstract

The Opecoeloidea is a large group of xiphidiate digeneans parasitizing marine and freshwater fishes. According to the current taxonomic model, this superfamily contains only one family with numerous subfamilies. This study is devoted to the members of the Stenakrinae. Based on phylogenetic analysis of concatenated sequences of 18S and 28S rRNA genes of stenakrine opecoelids Caudotestis dobrovolski, C. cf. dobrovolski, Hexagrammia zhukovi, Stenakron vetustum, as well as the deep-sea xiphidiate digenean Zdzitowieckitrema incognitum, which so far has had an ambiguous phylogenetic status, we erect a new opecoeloid family, the Zdzitowieckitrematidae fam. nov. The genera Holsworthotrema and Scorpidotrema are removed from the Stenakrinae to the Scorpidotrematinae subfam. nov. within the Opecoelidae. We also remove the Stenakrinae from the Opecoelidae and recognize it as a separate family within the Opecoeloidea. The Stenakridae stat. nov. is a sister taxon to a well-supported Opecoelidae. The Zdzitowieckitrematidae occupies a sister position relative to the stenakrids and the opecoelids taken together. All three families are clearly phylogenetically distinct, however convincing morphological differences are revealed only between the Zdzitowieckitrematidae and the Stenakridae and between the Opecoelidae and the Stenakridae.

A Review of Sperm Ultrastructural Characters in the Opecoelidae (Digenea) and Their Phylogenetic Implications, with New Data on Peracreadium characis, a Parasite of Diplodus puntazzo in Tunisia

“…The remaining analyzed subfamilies, namely the Helicometrinae, Opecoelinae and Plagioporinae, are homogeneous in relation to the pattern of the sperm cell. The similarity in the ultrastructure of spermatozoa between P. characis (present study) and Allopodocotyle species [ 28 , 29 ] suggests a close relationship between the Opistholebetinae and Hamacreadiinae subfamilies, and this finding is supported by genetic studies conducted by Sokolov et al [ 15 ]. However, using more extensive data, the phylogenetic analyses performed by Martin et al [ 13 ] are more robust and do not show a close relationship between these subfamilies.…”

“…The subfamily Hamacreadiinae Martin, Downie & Cribb, 2020 was created for the inclusion of species that use marine fishes as second intermediate hosts in their life cycles [ 14 ]. Recently, Sokolov et al [ 15 ] elevated the Stenakridae Yamaguti, 1970 from subfamily to family rank to be included in the Opecoeloidea, and also proposed the new family Zdzitowieckitrematidae Sokolov, Shchenkov, Frolov & Gordeev, 2022, recognizing it in the Opecoeloidea. Moreover, these authors also proposed the new subfamily Scorpidotrematinae Sokolov, Shchenkov, Frolov & Gordeev, 2022 to accommodate the genera Holsworthotrema Martin, Huston, Cutmore & Cribb, 2018 and Scorpidotrema Aken’Ova & Cribb, 2003, previously considered stenakrines.…”

“…Moreover, these authors also proposed the new subfamily Scorpidotrematinae Sokolov, Shchenkov, Frolov & Gordeev, 2022 to accommodate the genera Holsworthotrema Martin, Huston, Cutmore & Cribb, 2018 and Scorpidotrema Aken’Ova & Cribb, 2003, previously considered stenakrines. Thus, according to the modern concept, which is based on phylogenetic and morphological data, the family Opecoelidae is currently divided into 12 subfamilies, namely the Bathycreadiinae; Hamacreadiinae; Helicometrinae; Neopycnadeninae; Opecoelinae; Opecoelininae; Opistholebetinae Fukui, 1929; Plagioporinae; Podocotylinae; Polypipapiliotrematinae; Pseudoplagioporinae and Scorpidotrematinae [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ].…”

Redescription and First Nucleotide Sequences of Opecoeloides pedicathedrae (Digenea: Opecoelidae), a Parasite of Cynoscion leiarchus (Cuvier, 1830) (Eupercaria: Sciaenidae) from Brazil

“…Opecoeloides was assigned to Opecoelinae, and two genera, Abyssopedunculus Martin, Huston, Cutmore & Cribb, 2018, and Mesobathylebouria Martin, Huston, Cutmore & Cribb, 2018, remain without suitable subfamilial designation [2,[35][36][37]. Recently, Sokolov et al [38] proposed a new subfamily, the Scorpidotrematinae Sokolov, Shchenkov, Frolov & Gordeev, 2022, and removed the Stenakrinae from Opecoelidae, to recognize it as a separate family within Opecoeloidea, named Stenakridae Yamaguti, 1970.…”

Morphological and molecular characterization of Stomachicola muraenesocis Yamaguti, 1934 (Digenea: Hemiuridae) from the daggertooth pike conger Muraenesox cinereus (Forsskål)

“…Sequence data were generated using an automated sequencer (ABI 3730 XL) at LGC Biosearch™ Technologies (LGC Genomics GmbH, Berlin, Germany). Contiguous sequences were assembled manually, and base-calling were differences resolved using MEGA X and analysed with Chromas v2.6.6 to ensure accuracy (Sokolov et al ., 2022). The newly generated sequences have been deposited in GenBank under accession numbers OR552105-OR552108.…”