New records of 24 ciliate species (Protozoa, Ciliophora) collected in South Korea Author Kim, Ji Hye Natural Science Research Institute, Gangneung-Wonju National University, Gangneung, Republic of Korea Author Jung, Ji Hye Moon and Jae-Ho text Journal of Species Research 2018 7 4 291 314 journal article 10.12651/JSR.2018.7.4.291 2713-8615 13163147 15. Mesodinium pulex Claparède and Lachmann , 1858 ( Fig. 15 ) Material examined. Marine water (salinity 28‰) collected from Anin Beach , Gangdong-myeon , Gangneung-si , Gangwon-do , Korea ( 37°44 ʹ 4.7 ʺ N , 128°59 ʹ 24.2 ʺ E ) on June 1, 2018 . Fig. 14. Phialina salinarum in vivo (A-C) and after protargol impregnation (D). A. Typical individual. B. Details of oral extrusomes and macronucleus with cytoplasmic inclusions. C. Cortical granules. D. Oral and somatic ciliature with macronuclear apparatus. Scale bars= 50 μm (A); 30 μm (D). Fig. 15. Mesodinium pulex in vivo (A) and after protargol impregnation (B, C). A. Typical individual. B. Two macronuclear nodules. C. Somatic ciliature. Scale bars= 30 μm (A); 10 μm (B, C). Diagnosis. Body size about 38 × 23 μm in vivo ; about 15 × 12 μm after protargol impregnation; body pyriform; 2 oval macronuclei; 2 distinct ciliary girdles consisted of 23-28 short rows: anterior-most tuft obliquely and anteriorly directed, middle tuft horizontally directed and posterior most tuft obliquely posteriorly directed. Distribution. Cosmopolitan. Remarks. Mesodinium pulex is different from the most similar species, M. acarus Stein, 1867 , in the body length (38 μm vs. less than 20 μm) and number of macronuclei (2 vs. 1) ( Foissner et al ., 1999 ; Long et al ., 2009 ). Voucher slides. Two slides of protargol-impregnated specimens were deposited at National Institute of Biological Resources, Korea (NIBRPR0000109432, NI- BRPR0000109433) and one slide was deposited at the National Marine Biodiversity Institute of Korea (MABIK PR00043185).