A new Notomastus (Annelida, Capitellidae) species from Korean waters... 141 A new Notomastus (Annelida, Capitellidae) species from Korean waters, with genetic comparison based on three gene markers Man-Ki Jeong 1 , Ho Young Soh 2 , Jin Hee Wi 3 , Hae-Lip Suh 4 1 Te Fisheries Science Institute, Chonnam National University, Daehak-ro, Yeosu 59626, South Korea 2 Faculty of Marine Technology, Chonnam National University, Daehak-ro, Yeosu 59626, South Korea 3 School of Environmental Science and Engineering, Gwangju Institute of Science and Technology, Choemdangwagi- ro, Buk-gu, Gwangju 61005, South Korea 4 Department of Oceanography, Chonnam National University, Yongbong-ro, Buk-gu, Gwangju 61186, South Korea Corresponding authors: Ho Young Soh (hysoh@chonnam.ac.kr); Hae-Lip Suh (suhhl@chonnam.ac.kr) Academic editor: C. Glasby  |  Received 31 January 2018  |  Accepted 26 April 2018  |  Published 4 May 2018 http://zoobank.org/99197F00-54A7-457D-92AC-4F6D5D2BF08E Citation: Jeong M-K, Soh HY, Wi JH, Suh H-L (2018) A new Notomastus (Annelida, Capitellidae) species from Korean waters, with genetic comparison based on three gene markers. ZooKeys 754: 141–155. https://doi.org/10.3897/ zookeys.754.23655 Abstract Notomastus koreanus sp. n., collected from the sublittoral muddy bottom of Korean waters, is described as a new species. Te Korean new species closely resembles N. torquatus Hutchings & Rainer, 1979 in the chaetal arrangement and the details of abdominal segments, but difers in the position of genital pores and the absence of eyes. DNA sequences (mtCOI, 16S rRNA, and histone H3) of the new species were com- pared with all the available sequences of Notomastus species in the GenBank database. Tree genes showed signifcant genetic diferences between the new species and its congeners (COI: 51.2%, 16S: 38.1–47.3%, H3: 3.7–9.3%). Tis study also includes a comprehensive comparison of the new Korean Notomastus species with its most closely similar species, based on the morphological and genetic results. Keywords Polychaeta, Notomastus koreanus sp. n., morphology, DNA barcoding, COI, 16S rRNA, histone H3, South Korea ZooKeys 754: 141–155 (2018) doi: 10.3897/zookeys.754.23655 http://zookeys.pensoft.net Copyright Man-Ki Jeong et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. RESEARCH ARTICLE Launched to accelerate biodiversity research A peer-reviewed open-access journal