Mycetomorpha vancouverensis is an enigmatic parasitic barnacle from the family Mycetomorphidae, known for its unclear phylogenetic position within Rhizocephala. Specimens of M. vancouverensis were collected from infected Neocrangon communis shrimps near the South Kuril Islands. Detailed morphological studies were conducted using histological techniques and scanning electron microscopy, and 18S rDNA sequences were used to resolve the phylogenetic position of M. vancouverensis within Rhizocephala. Morphological analysis revealed a complex externa structure with spermatogenic bodies and the presence of a main trunk in the interna. Some of the side branches of the interna invade the host’s nerve tissue and are modified into specialized goblet-shaped organs. These invasive rootlets are morphologically similar to the goblet-shaped organs in the family Peltogastridae. Molecular analysis confirmed that the Mycetomorphidae is a sister group to the Peltogastridae. At the same time, peltogastrids were recovered as polyphyletic. Our findings contribute to the understanding of the evolution of parasitic barnacles and highlight the unique adaptations of Mycetomorphidae within the broader context of Rhizocephala.

The results of ichthyoparasitological studies of fish in the coastal waters of southeastern Sakhalin are presented. Standard parasitological methods of work were used. 20 species of fish were discovered. 33 species and undefined forms of helminths were found. For 11 species of helminths (Bothriocephalus scorpii, Eubothrium salvelini, Prosorhynchus crucibulum, Steringophorus furciger, Liliatrema skrjabini mtc., Podocotyle cf. reflexa, Echinorhynchus gadi, Echinorhynchus cotti, Corynosoma strumosum juv., Corynosoma semerme juv., Clavinema mariae) of southeastern Sakhalin, new hosts have been noted. Helminths Prosorhynchus crucibulum, Echinorhynchus cotti were first recorded in coastal fish of Sakhalin.

В работе обозначена теоретическая возможность использования личинок Anisakis simplex и Dibothriocephalus nihonkaiensis в качестве биологических меток для разграничения локальных стад горбуши южного Сахалина. Установлены различия заражённости генераций горбуши чётных и нечётных лет. Выявлены различия заражённости япономорской и тихоокеанской локальных группировок рыб.

The purpose of the research is to describe and analyze the qualitative and quantitative composition of pink salmon helminths of southeastern Sakhalin.Materials and methods. Standard parasitological methods of collecting material were used. At the autopsy, the ureters, eyeballs, gill petals and arches, and the brain of fish were not examined. The method of collecting salmon parasites in the laboratory has been unchanged since 1992. Collections of representatives of monogenetic suckers were not carried out. Parasitological studies of pink salmon of southeastern Sakhalin were carried out from 1992 to 2022, a total of 4163 fish specimens were examined. The fish is caught in the estuaries of rivers and the sea coast.Results and discussion. According to the results of their own research and literature data, the pink salmon helminth fauna of southeastern Sakhalin is represented by 23 species: Dibothriocephalus nihonkaiensis pl., Eubothrium salvelini, Eu. crassum, Nybelinia surmenicola pl., Pelichnibothrium speciosum pl., Tetraphyllidea gen. sp., Brachyphallus crenatus, Cryptocotyle sp. mtc., Hemiurus levinseni, Lecithaster gibbosus, Prosorhynchoides gracilescens, Parahemiurus merus, Derogenes varicus, Capiatestes thyrsitae, Corynosoma strumosum l., Echinorhynchus gadi, Bolbosoma caenoforme juv., B. bobrovoi juv., Rhadinorhynchus trachuri, Anisakis simplex l., Ascarophis pacifica, Ascarophis skrjabini, Hysterothylacium aduncum. The qualitative composition of the helminth fauna is currently undergoing minor changes, while the quantitative characteristics of some helminths are significantly reduced. Thus, the infection of pink salmon with Bolbosoma sp. juv scrapers. decreased to 0.61±0.18.

The paper reports the results of ichthyoparasitological studies on saffron cod (Eleginus gracilis) caught in the coastal waters near the village of Trambaus (northwestern Sakhalin) in 2024. Standard parasitological methods (Bykhovskaya-Pavlovskaya 1985) were applied, with 100 specimens of saffron cod examined. According to the existing literature, helminth fauna of the coastal waters around Sakhalin includes 19 species of helminths and a few more indeterminate taxonomic forms. Based on the results of the original research, 12 species and forms of helminths, including those indeterminate to the type, were identified. Notably, this study reports for the first time the presence of two helminth species in saffron cod from the coastal waters around Sakhalin: Echinorhynchus cotti, and Corynosoma cf. villosum juv. Представлены результаты ихтиопаразитологических исследований наваги, выловленной в прибрежных участках близ с. Трамбаус (северо-западный Сахалин) в 2024 г. Использованы стандартные паразитологические методы работы (Быховская-Павловская 1985). Вскрыто 100 экземпляров наваги. По литературным данным, гельминтофауна наваги прибрежных вод о. Сахалин представлена 19 видами и не определенных до вида формами гельминтов. По результатам оригинальных исследований выявлено 12 видов и неопределенных до вида форм гельминтов. У наваги прибрежных вод о. Сахалин впервые зарегистрированы два вида гельминтов (Echinorhynchus cotti, Corynosoma cf. villosum juv.).

The first case of Pyramicocephalus phocarum pl. parasitism on pacific capelin Mallotus catervarius is registered.