Discovery of Anchimolgus jejuicus n. sp. (Copepoda, Cyclopoida, Anchimolgidae) Associated with the Scleractinian Coral Alveopora japonica Eguchi (Cnidaria) off Jeju Island, Korea: Systematics and Ecological Insights

A new species of copepod, Anchimolgus jejuicus n. sp., is described based on specimens collected from the external washings of the scleractinian coral Alveopora japonica Eguchi, 1965, off Jeju Island, Korea. The new species closely resembles A. multidentatus Kim, 2003, associated with Alveopora catalai Wells, 1968, from New Caledonia in having similar body lengths and similar shapes of the antennae, mouth organs, and swimming legs. However, the new species can be distinguished from the New Caledonian species by the shorter female caudal ramus, which is 1.70 times longer than wide; by the shorter third endopodal segment of the female antenna, which is 3.35 times longer than wide; by the reduced second spine of the distal lash of the maxilla, which is less than half as long as the first spine; by the relatively shorter inner distal spine of the second endopodal segment of female leg 4, which is 1.56 times longer than the outer spine; by the shorter exopodal segment of female leg 5, which is 3.39 times longer than wide; and by the exopod of male leg 5 armed with one spine and one seta. The present paper reports the northernmost distribution area of the genus Anchimolgus, near the latitude of 33°24′ N off Jeju Island. In addition, the recent rapid increase in populations of the host coral Alveopora japonica around Jeju Island—likely driven by climate change—highlights the significant ecological consequences for both the scleractinian coral and its newly discovered symbiotic copepod.