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.