First Specimen Based Record of Anthessius cucullatus (Copepoda: Cyclopoida: Anthessiidae) Associated with Aplysia spp. (Gastropoda: Aplysiida: Aplysiidae) from Coastal Waters of Kagoshima, Southern Japan

A species of cyclopoid copepod Anthessius cucullatus Lee and Kim, 2021 (Anthessiidae) is newly recorded based on both sexes collected from three species of the sea slug genus Aplysia Linnaeus, 1767, i.e., Ap. dactylomela Rang, 1828, Ap. juliana Quoy and Gaimard, 1832, and Ap. kurodai Baba, 1937, from coastal waters of Kagoshima Prefecture, southern Japan. The copepod is characterized by having the following characters in the female: 1) the genital double somite covered with a hood-like dorsal lobe; 2) the antenna with four unequal claws and three setae at the distal tip; 3) the maxilla has a spinulose basal lobe; 4) leg 5 with irregular marginal rows of spinules. Furthermore, the male has 5) the third endopodal segment of leg 4 bearing a curved third inner spine. The findings of An. cucullatus in this study represent the second record of the copepod from all around the world as well as the first record from Japanese waters with the detailed description of the morphological characters based on the specimens. Aplysia dactylomela and Ap. juliana are new host records of the copepod.