A new Gammarus species (Crustacea, Amphipoda, Gammaridae) from Northwestern Islands, South Korea Author Kwon, So-Yeon 0000-0001-5807-1037 Department of Life Sciences, Dankook University, Cheonan, KOREA 31116 & sy. kwon 18 @ gmail. com; https: // orcid. org / 0000 - 0001 - 5807 - 1037 & National Marine Biodiversity Institute of Korea, Seocheon, KOREA 33662 sy.kwon18@gmail.com Author Kim, Min-Seop 0000-0001-5807-1037 sy. kwon 18 @ gmail. com; https: // orcid. org / 0000 - 0001 - 5807 - 1037 & National Marine Biodiversity Institute of Korea, Seocheon, KOREA 33662 sy.kwon18@gmail.com Author Heo, Jun-Haeng 0000-0003-0942-7126 Department of Life Sciences, Dankook University, Cheonan, KOREA 31116 & tyrant 1047 @ naver. com; https: // orcid. org / 0000 - 0003 - 0942 - 7126 tyrant1047@naver.com Author Kim, Young-Hyo 0000-0002-7698-7919 Department of Life Sciences, Dankook University, Cheonan, KOREA 31116 & yhkim @ dankook. ac. kr; https: // orcid. org / 0000 - 0002 - 7698 - 7919 yhkim@dankook.ac.kr text Zootaxa 2020 2020-12-23 4896 4 535 546 journal article 9206 10.11646/zootaxa.4896.4.5 b74e6677-e056-459b-8781-3f3ade783f8c 1175-5326 4387901 8F11E9BD-CA99-4999-8D99-27554C95EAB2 Key to Korean Gammarus species with calceoli on antenna 2 (modified after Kim et al. , 2010 ). 1. Uropod 3, both rami with plumose setae................................................................... 2 - Uropod 3, both rami without plumose setae................................... G . gageoensis Kim, Lee & Min, 2010 2. Uropod 3, inner ramus relatively short, length ratio of outer ramus to inner ramus less than 0.7; telson sparse, with short setae........................................................................ G. zeongogensis Lee & Kim, 1980 - Uropod 3, inner ramus relatively long, length ratio of outer ramus to inner ramus more than 0.7; telson setose, with long setae............................................................................ G . baengnyeongensis sp. nov.