The phylogenomic approach has largely resolved metazoan phylogeny and improved our knowledge of animal evolution based on morphology, paleontology, and embryology. Nevertheless, the placement of two major lophotrochozoan phyla, Entoprocta (Kamptozoa) and Ectoprocta (Bryozoa), remains highly controversial: Originally considered as a single group named Polyzoa (Bryozoa), they were separated on the basis of morphology. So far, each new study of lophotrochozoan evolution has still consistently proposed different phylogenetic positions for these groups. Here, we reinvestigated the placement of Entoprocta and Ectoprocta using highly complete datasets with rigorous contamination removal. Our results from maximum likelihood, Bayesian, and coalescent analyses strongly support the topology in which Entoprocta and Bryozoa form a distinct clade, placed as a sister group to all other lophotrochozoan clades: Annelida, Mollusca, Brachiopoda, Phoronida, and Nemertea. Our study favors the evolutionary scenario where Entoprocta, Cycliophora, and Bryozoa constitute one of the earliest branches among Lophotrochozoa and thus supports the Polyzoa hypothesis.

Opecoelid speciesPseudopecoelus cf.vulgarisandAnomalotrema koiaeGibson & Bray, 1984 were found in fish collected in the boreal waters of the North Pacific.Pseudopecoelus cf.vulgarisdiffers fromPseudopecoelusvulgaris(Manter, 1934) in terms of the egg size. This is the first record ofA. koiaein the North Pacific, and the second ofPseudopecoeluscf.vulgaris.Previously,A. koiaewas recorded only in North Atlantic fish. Partial sequences of 28S rDNA obtained for these two species and six other previously unsequenced representatives of the family Opecoelidae were analysed together with data from GenBank. Phylogenetic analysis supports the allocation of the six clades of opecoelids – Helicometrinae, Opecoelinae, Opistholebetinae, ‘freshwater Plagioporinae’, ‘marine Plagioporinae B’ and ‘marine Plagioporinae C’, and confirms the paraphyly of the group ‘deep-sea Plagioporinae’. Our phylogeny does not support previous hypotheses about the monophyly of opecoelines with a uroproct.

The phylogenetic position of most xiphidiocercariae from subgroups Cercariae virgulae and Cercariae microcotylae remains unknown or unclear, even at the family level. In this paper, we studied the morphology and molecular phylogeny of 15 microcotylous and virgulate cercariae (11 new and four previously described ones). Based on morphological and molecular data, we suggested five distinct morphological types of xiphidiocercariae, which are a practical alternative to Cercariae virgulae and Cercariae microcotylae subgroups. Four of these types correspond to actual digenean taxa (Microphallidae, Lecithodendriidae, Pleurogenidae and Prosthogonimidae), while the fifth is represented by Cercaria nigrospora Wergun, 1957, which we classified on the basis of molecular data for the first time. We reassessed the relative importance of morphological characters used for the classification of virgulate and microcotylous cercariae, and discussed the main evolutionary trends within xiphidiocercariae. Now stylet cercariae can be reliably placed into several sub-taxa of Microphalloidea on the basis of their morphological features.

In this study, we elucidated the phylogenetic position of a Pacific species Pronoprymna petrowi, a Caspian species Pronoprymna ventricosa, an Antarctic species of the genus Steringophorus, S. liparidis, and a new species of the same genus, S. occidentalipacificus sp. nov. The new species was found in a bathylagid fish Leuroglossus schmidti from the Sea of Okhotsk. Steringophorus occidentalipacificus sp. nov. is similar to S. congeri, and differs from it in the length of the body and the forebody, the shape of the testes, the sucker-ratio, the size of eggs and the extension of the caeca and the cirrus-sac. The 28S rRNA gene-based analyses supported a sister relationship between Pr. petrowi and Pr. ventricosa, and put the genus Pronoprymna into to the group of faustulids (sensu lato), which is nested within the Gymnophaloidea clade. Based on the results of these analyses, Steringophorus is identified as a paraphyletic taxon within the Fellodistomidae (Gymnophalloidea). Phylogenic reconstructions also support a morphologically identified sister relationship between S. liparidis and S. thulini and demonstrate a close relationship of S. occidentalipacificus sp. nov. with S. blackeri and S. pritchardae. The analysis of the nd1 gene sequences also confirmed the phylogenetic affinity of S. liparidis to S. thulini. urn:lsid:zoobank.org:pub:6217E5D2-00FD-4135-A8DA-CDBAFACA52