Purpose

Many nematode species parasitizing marine fishes were reported from Japanese waters. However, considering the wealth of fish species in this zoogeographically interesting region and the host specificity of nematodes, the number of hitherto recorded fish nematodes probably represents only a very small part of the potential Japanese fauna of these organisms. Therefore, new data are needed to recognise the species composition of these parasites in this region.

Methods

Helminthological examinations of some marine fishes from off Japan, carried out in the years 2005–2017, revealed one new and five insufficiently known species of ascaridoid and seuratoid nematodes. These were studied with the use of light and scanning electron microscopy.

Results

All six nematode species recorded are described: Anisakidae: Raphidascaris (Ichthyascaris) multipapillata sp. nov. (male and females) from the intestine of Labracoglossa argenteiventris Peters (Kyphosidae) in the Sea of Japan, Raphidascaris (Ichthyascaris) sp. (third-stage larvae) probably from the digestive tract of Seriola dumerili (Risso) and S. rivoliana Valenciennes (both Carangidae) in the western North Pacific Ocean off Ishigaki-jima Island, Okinawa Prefecture, Hysterothylacium simile Li et al., 2013 (males and females) from the stomach of Lateolabrax japonicus (Cuvier) (Lateolabracidae) in the Sea of Japan, Hysterothylacium sp. 1 (female) from the pyloric caeca of Jaydia lineata (Temminck et Schlegel) (Apogonidae) in the Seto Inland Sea, Hysterothylacium sp. 2 (third- and fourth-stage larvae) from the intestine and mesentery of Etelis coruscans Valenciennes (Lutjanidae) and Pseudorhombus pentophthalmus Günther (Paralichthyidae) in the western North Pacific Ocean off Ishigaki-jima Island, Okinawa Prefecture and the Seto Inland Sea, respectively; and Cucullanidae: Cucullanus sp. (female) from the intestine of Semicossyphus reticulatus (Valenciennes) (Labridae) in the Seto Inland Sea. Raphidascaris (I.) multipapillata sp. n. differs from congeners mainly in the high number (79) of pairs of caudal papillae, spicules 402 µm long and in the structure of the male and female tail tips. Hysterothylacium simile is redescribed, being recorded from off Japan for the first time.

Conclusions

In addition to the discovery of the new nematode species R. (I.) multipapillata sp. nov. and a redescription of H. simile providing some new morphological data of this parasite, the findings of all other species represent new host and geographical records. The present study extends the knowledge of the species composition and host–parasite relationships of nematodes parasitizing marine fishes.

中文翻译：

---

Raphidascaris ( Ichthyascaris ) multipapillata sp. 的描述。十一月，重新描述 Hysterothylacium simile Li 等人。, 2013 及日本海鱼中其他蛔虫和鳞状线虫的新记录

目的

据报道，日本水域有许多寄生于海洋鱼类的线虫物种。然而，考虑到这个动物地理学上有趣的地区鱼类种类丰富，以及线虫的寄主特异性，迄今为止记录的鱼类线虫数量可能仅占这些生物潜在日本动物群的很小一部分。因此，需要新的数据来识别该地区这些寄生虫的物种组成。

方法

2005 年至 2017 年对日本近海的一些海洋鱼类进行的蠕虫学检查揭示了一种新的和 5 种未知的蛔虫和丝状线虫。使用光学显微镜和扫描电子显微镜对这些进行了研究。

结果

描述了记录的所有六种线虫：异尖线虫科：Raphidascaris ( Ichthyascaris ) multipapillata sp。十一月 （雄性和雌性）来自日本海的Labracoglossa argenteiventris Peters（Kyphosidae），Raphidascaris（Ichthyascaris）sp。（第三阶段幼虫）可能来自Seriola dumerili (Risso) 和S的消化道。rivoliana Valenciennes (both Carangidae) 在冲绳县石垣岛附近的北太平洋西部，Hysterothylacium simile Li等。, 2013 (男性和女性) 从胃日本海中的Lateolabrax japonicus (Cuvier) (Lateolabracidae)，Hysterothylacium sp。1（雌性）来自濑户内海的Jaydia lineata（Temminck et Schlegel）（Apogonidae）的幽门盲囊，Hysterothylacium sp。2（第三和第四阶段幼虫）分别来自冲绳县石垣岛和濑户内海的北太平洋西部的Etelis coruscans Valenciennes (Lutjanidae) 和Pseudorhombus pentophthalmus Günther (Paralichthyidae)的肠道和肠系膜; 和Cucullanidae：Cucullanus sp。（雌性）来自Semicossyphus reticulatus的肠道(Valenciennes) (Labridae) 在濑户内海。Raphidascaris ( I .) multipapillata sp. n. 与同类物的主要区别在于尾乳头对的数量较多（79），针状体长 402 µm，雄性和雌性尾尖的结构也不同。Hysterothylacium simile被重新描述，首次在日本外被记录。

结论

除了发现新的线虫物种R . ( I .) multipapillata sp. 十一月 和H的重新描述。比喻提供了这种寄生虫的一些新形态数据，所有其他物种的发现代表了新的宿主和地理记录。本研究扩展了对寄生于海洋鱼类的线虫的物种组成和寄主-寄生虫关系的认识。