Distribution of Acartia (Odontacartia) pacifica and its sibling species based on data from this and previously published reports. In the present study, samples were obtained from three sites: Station 1, Acartia (Odontacartia) edentata sp. n., Leyte Island, the Philippines (black donut); Station 2, A. (O.) pacifica, Ariake Bay in the Seto Inland Sea, Japan (white donut); and Station 3, A. (O.) pacifica, South Korea Sea, Korea. Data from earlier studies indicate the distribution of A. (O.) pacifica in the Pacific Ocean (Steuer 1915; Tanaka 1965; Brodsky 1967; Ueda and Bucklin 2006); Korean waters (Kang 2011); the Yellow Sea, Chiekong River, Juilong Estuary, Changjiang Estuary, China (Shen and Lee 1963; Chen and Zhang 1965; Shang et al. 2007; Gao et al. 2008); eastern Indonesian waters of Java Sea, Bintulu coast, Indonesia (Früchtl 1923; Mulyadi 2004; Johan et al. 2013); the Gulf of Thailand (Pinkaew 2003); the Indian Ocean (Sewell 1933; Wellershaus 1969; Pillai 1971; Resai et al. 2004; Phukham 2008; Treeramaethee et al. 2013); water of the Great Barrier Reef, Moreton Bay, Australia (Farran 1936; Greenwood 1978); and type locality of A. (O.) pacifica (black square).