- 著者
- KATSUHIKO TANAKA
- 出版者
- The Plankton Society of Japan, The Japanese Association of Benthology
- 雑誌
- Plankton and Benthos Research (ISSN:18808247)
- 巻号頁・発行日
- vol.2, no.1, pp.1-11, 2007 (Released:2008-05-09)
- 参考文献数
- 71
- 被引用文献数
- 45 53
Gnathiidae is a family of Isopoda, showing a distinct morphology and ecology. Species in the family have ten walking legs compared to 14 for isopods in general. The life cycle of the Gnathiidae is biphasic including a fish-parasitic larval phase and a non-feeding adult phase, whereas most other isopods have a monophasic life cycle with direct-developing young similar to adults in morphology and ecology. Although the ecological information on gnathiids has been described fragmentally, studies on the life cycles and population biology have increased dramatically since the 1980's. Larval biology including the host species, emergence pattern and predation risks during parasitism have also been studied from the view of fish disease and symbiotic interactions among fishes. Some authors reported the utilization patterns of benthic substrata and harem formation of adults therein. However, the ecological knowledge of gnathiids is based on a limited number of species of which the benthic habitats are known. Studies rarely identify larvae because of the lack, or insufficiency, of the taxonomic description of larvae of most species. The difficulty in identifying larvae has prevented detailed examination of ectoparasitic behaviour. Furthermore, gnathiid larvae emerging from the benthos or attaching to hosts have been investigated separately from benthic individuals. More efforts on taxonomy and the classification of larvae are necessary to elucidate the larval ecology and the integration of larval and adult biology.
- 著者
- Yuzo Ota Hisanori Kohtsuka Katsuhiko Tanaka
- 出版者
- The Japanese Society of Systematic Zoology
- 雑誌
- Species Diversity (ISSN:13421670)
- 巻号頁・発行日
- vol.26, no.2, pp.207-216, 2021-09-10 (Released:2021-09-10)
- 参考文献数
- 32
Adult male and larva of Gnathia capitellum sp. nov. (Crustacea: Isopoda: Gnathiidae) are described. The specimens were laboratory-reared larvae that infested host fishes collected by longline fishing in a coastal bay of Izu Peninsula and adult males found in dredge samples from shallow water (depth: 11–12 m) of Miura Peninsula, central Japan. Adult males of G. capitellum sp. nov. were easily distinguished from the other species of Gnathia Leach, 1814 from around the world by the small oval head and the inner margin of pylopod without plumose setae. Most other Gnathia species have a large rectangular head and plumose setae present on the article 1 of pylopod. Appearance of the adult male resembles the genus Afrignathia Hadfield and Smit, 2008 rather than Gnathia but Afrignathia has maxilla 1 which is absent in all known male gnathiids in the world including G. capitellum sp. nov. Fish parasitic larva of G. capitellum sp. nov. is also described herein. This larva closely resembles larvae of the genus Gnathia, but can be distinguished from the other Gnathia species by the remarkably oval-shaped basis in pereopods 2–4.