Bioacoustics of Dysteria semilunaris

Remarks. The descriptions by Gourret and Roeser (1888) and Kahl (1931) did not provide detailed information of body size and infraciliature. Nevertheless, the D. semilunaris can be easily identified by the body shape and marine habitat. The Korean population of D. semilunaris differs from the two Chinese populations (Qingdao and Shanghai ) in number of right kineties (4-5 vs. consistently 4 in both populations), presence of longitudinal groove (left and right plates vs. left only vs. right only), and transverse stripe at the equatorial region (absent in the Korean and Qingdao population vs. present in Shanghai population) ( Gong et al. , 2007 ; Pan et al. , 2016 ). The closest congeners D. ovalis (Gourret and Roeser, 1886) Kahl, 1931 and D. crassipes Claparède & Lachmann, 1859 can be distinguished from D. semilunaris as follows: (1) absence of an extra short row below the anterior end of the frontoventral kineties; (2) absence of a longitudinal groove on the both plate; (3) subcaudally-located podite ( Gong et al. , 2007 ; Park and Min, 2015 ; Pan et al. , 2016 ). Additionally, D. calkinsi Kahl, 1931 differs from D. semilunaris in the following features: arrangement of contractile vacuoles (diagonally positioned in original description but not detected in Antarctic population vs. longitudinally positioned); number of groove on the left plate (two vs. one); extra short row below the end of frontoventral kineties (absent vs. present); number of left frontal kineties (two vs. three) ( Kahl, 1931 ; Song and Wilbert, 2002 ; Gong et al. , 2007 ). Voucher slides. Two slides with protargol-impregnated specimens was deposited at National Institute of Biological Resources (NIBRPR0000110832) and Korea Institute of Ocean Science and Technology (KIOST), respectively.