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 22. Pseudovorticella difficilis (Kahl, 1933) Jankowski , 1976 ( Fig. 22 ) Material examined. Marine water (salinity 29.6‰) 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 May 24, 2018 . Diagnosis. Zooid size 45-50 × 32-39 μm in vivo ; invert- ed bell-shaped; peristomial lip width about 41-47 μm; annular swellings present on stalk; macronucleus longitudinally oriented J-shape; one contractile vacuole dorsally located; rectangular silverlines about 35 striations between peristomial lip and trochal band, about 18 striations between trochal band and scopula; P1-P3 consisted of 3 rows, shorter inner 1 row of P3, longer and closely spaced outer 2 rows of P3. Distribution. China , Germany , Korea . Remarks. The Korean population of P. difficilis is slightly different from the Chinese population in the zooid size (45-50 μm vs. 50-70 μm) ( Ji et al ., 2006 ; Sun et al ., 2009 ). A freshwater P. difficilis var. magnistriata is larger than the marine Korean population (60-140 μm vs. 45-50 μm) and fewer transverse silverlines between peristomial lip and trochal band (25-31 vs. 35) ( Foissner and Schiffmann, 1974 ; Ji et al ., 2006 ). Voucher slides. Two slides of protargol-impregnated specimens were deposited at National Institute of Biological Resources, Korea (NIBRPR0000109437, NI- BRPR0000109438) and four slides were deposited at the National Marine Biodiversity Institute of Korea (MABIK PR00043196-PR00043199).