著者

Yuzo Ota

出版者

Carcinological Society of Japan

雑誌

Crustacean Research (ISSN:02873478)

巻号頁・発行日

vol.48, pp.133-143, 2019-11-28 (Released:2019-11-28)

参考文献数

20

被引用文献数

3 5

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Monthly quadrat sampling of freshwater shrimps infested by the corallanid isopod Tachaea chinensis was conducted in Lake Biwa, central Japan, between April 2014 and September 2015. In total, 3,222 shrimps, including 2,786 Neocaridina spp., 309 Paratya improvisa, and 127 Palaemon paucidens were collected. Individuals of 431 T. chinensis were found from those hosts. The prevalence was 12.2% in Neocaridina spp., 5.5% in P. improvisa, and 24.4% in P. paucidens, respectively. All isopods found on hosts were immature stages and showed an annual emergence pattern; newly hatched juveniles were first sampled in August, increased the body length until May, and were not observed in June–July. To collect T. chinensis apart from the hosts, a cage trap filled with reed roots was put on the study site between June 2014 and September 2015. Isopods were collected in July and September. Specimens trapped in 2015 consisted of adult or premature individuals, and 39 out of 46 adult females collected were ovigerous. During an observation using snorkeling in July 2014, 29 adults were observed under stones and in withered Phragmites australis roots. Thus, T. chinensis reproduces in benthic habitats during summer. Subsequently, juveniles appear and grow via a series of molts on the hosts until the following year.

著者

Yusuke Yamana Yuzo Ota Hisanori Kohtsuka Kazumi Yoshizaki

出版者

The Japanese Society of Systematic Zoology

雑誌

Species Diversity (ISSN:13421670)

巻号頁・発行日

vol.25, no.2, pp.227-236, 2020-10-16 (Released:2020-10-16)

参考文献数

17

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A new dendrochirotid sea cucumber, Massinium japonicum sp. nov., is described from areas in western Japan, including the middle of the Seto Inland Sea, west of the Sea of Japan, the shore of the Amakusa Peninsula, and the shore of the Kii Peninsula. The ossicle assemblage of the new species (M. japonicum) is similar to that of M. maculosum Samyn and Thandar, 2003, the type species of Massinium Samyn and Thandar, 2003. However, the new species is readily distinguishable from M. maculosum and its congeners by the absence of rod/elongated rosette ossicles in the tentacles. The tentacle ossicles of the new species comprise only oval, simple, open rosettes, 20–40 µm in length, while the other congeners possess rods/elongated rosette-shaped ossicles in the tentacles (very rarely also table ossicles). This new species has been collected from the shallow waters of western Japan living amongst boulder area in the intertidal-subtidal zone, at a depth of approximately 0–20 m.

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

被引用文献数

1

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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.

著者

Masayuki Osawa Yuzo Ota

出版者

The Japanese Society of Systematic Zoology

雑誌

Species Diversity (ISSN:13421670)

巻号頁・発行日

vol.25, no.2, pp.295-307, 2020-10-28 (Released:2020-10-28)

参考文献数

77

被引用文献数

1

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Six decapod crustacean species, including one gebiidean and five anomurans, are reported as new to the marine fauna in the Sea of Japan based on material collected from the coast of Tottori Prefecture, western Japan. Among them, the munidid squat lobster Paramunida tricarinata (Alcock, 1894) is new to the Japanese fauna. In addition to the six species, the occurrence of the diogenid hermit crab Paguristes versus Komai, 2001 in the Sea of Japan is confirmed on the basis of specimens newly obtained from Tottori Prefecture. The current knowledge on the fauna of Gebiidea and Anomura in the western Japanese coast of the Sea of Japan is also briefly summarized.