Nematodes of the family Philometridae Baylis & Daubney, 1926 (Dracunculoidea Stiles, 1907) are generally poorly known, and there are many taxonomic issues within the family. Philometrids are parasites of fish and are found in various locations throughout the host, including within the subcutaneous tissues and musculature, the abdominal cavity and gonads; vast sexual dimorphism often means the males are not collected, leading to many species being described solely on female characteristics. Although there have been a number of studies utilising molecular data, the vast majority of species are yet to be sequenced. This study undertook genetic sequencing of 15 recently described species of philometrids across 4 genera, many of which were from specimens collected from waters off Australia. All of the sequences obtained were closely related with representatives of the family Philometridae. Species were found to be distributed in the phylogenetic trees within 4 clades based on a combination of site of infection within the host and host habitat. Family of host and geographical location was not as important for position within the trees. Clade A contained philometrids collected from the abdominal cavities and head tissues of South American freshwater fish. Clade B contained philometrids primarily from the abdominal cavities of freshwater European cyprinids. Clade C contained philometrids primarily from the ovaries of marine fish. Clade D contained philometrids from the body tissues of marine and freshwater fish. The potential co-evolutionary patterns between philometrids and their fish hosts are highlighted as an area of future research. This research also highlighted the importance of correct identification of any sequenced specimen.

• Klíčová slova
• Fish parasites, Molecular, Philometridae, Phylogeny,
• MeSH
• Dracunculoidea * MeSH
• fylogeneze MeSH
• nemoci ryb * MeSH
• RNA ribozomální 18S MeSH
• ryby MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• RNA ribozomální 18S MeSH

PURPOSE: Despite the fact that Okinawa Prefecture represents a very interesting subtropical region of Japan, its fauna of nematodes parasitizing fishes is still little-known. Therefore, new data are needed to recognize the species composition of these parasites in this zoogeographically remarkable region. METHODS: Helminthological examinations of some freshwater and brackish-water fishes in Okinawa Prefecture carried out in the years 2010, 2016 and 2018, revealed two new and four insufficiently known species of spirurid nematodes (Spirurida), all gastrointestinal parasites. These were studied with the use of light and scanning electron microscopy. RESULTS: All nematode species recorded are described: Rhabdochonidae: Rhabdochona honshuensis Moravec et Nagasawa, 1989 from Glossogobius celebius (Valenciennes) (Gobiidae, Perciformes) (new host), Rhabdochona iriomotensis sp. nov. from Ophieleotris sp. (Eleotridae, Perciformes) and Rhabdochona sp. (only females) from Eleotris acanthopoma Bleeker and E. fusca (Forster) (both Eleotridae, Perciformes); Cystidicolidae: Spinitectus mirabilis sp. nov. from Kuhlia rupestris (Lacepède) (Kuhliidae, Perciformes) and Spinitectus sp. larvae from E. acanthopoma; and Camallanidae: Procamallanus (Spirocamallanus) sp. (fourth-stage larva) from Yongeichthys criniger (Valenciennes) (Gobiidae, Perciformes). Rhabdochona iriomotensis sp. nov. is very similar to R. honshuensis, but differs from it in the presence of well-developed ventral precloacal ridges. Spinitectus mirabilis sp. nov. differs from its congeners and all other cystidicolids in having eggs provided with both lateral swellings and polar filaments. CONCLUSIONS: In addition to the discovery of two new nematode species, Rhabdochona iriomotensis sp. nov. and Spinitectus mirabilis sp. nov., the findings of all other species represent new host and geographical records. Rhabdochona denudata honshuensis Moravec et Nagasawa, 1989 is elevated to the level of an independent species R. honshuensis.

• Klíčová slova
• East Asia, Fish, Parasitic nematode, Procamallanus (Spirocamallanus), Rhabdochona, Spinitectus,
• MeSH
• hlístice * MeSH
• mikroskopie elektronová rastrovací MeSH
• nemoci ryb * epidemiologie   MeSH
• ryby MeSH
• sladká voda MeSH
• Spirurida * MeSH
• voda MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Japonsko epidemiologie   MeSH
• Názvy látek
• voda MeSH