Poecilostomatoid copepods associated with two species of widely distributed corals, Galaxea astreata (Lamarck, 1816) and Galaxea fascicularis (Linnaeus 1767), in the South China Sea

Seven species of copepods (Copepoda, poecilostomatoida) including two new species and five new records are described as associates of two widely distributed scleractinian corals, Galaxea astreata (Lamarck 1816) and Galaxea fascicularis (Linnaeus 1767), from Dongsha atoll (Pratas Island) in the South China Sea (SCS). They are: Anchimolgus amplius nov. sp., Anchimolgus contractus Humes 1979, Anchimolgus nasutus Humes 1996, Anchimolgus tanaus Humes 1991, Clamocus spinifer Humes 1979, Karanges hypsorophus Humes 1979, and Xarifia dongshensis nov. sp. Anchimolgus amplius nov. sp. can be readily distinguished from its congeners by the following features: (1) the larger body size (1.95 mm), (2) the three digitiform processes on the convex side of the mandible, (3) the third segment of leg 4 exopod arming with four spines, (4) the slender genital double-somite, (5) the caudal ramus with ratio less than 3:1, and (6) the second segment of abdominal somites distinctly shorter than others. Xarifia dongshensis nov. sp. can be readily distinguished from its congeners by the possession of (1) the bulge on the second segment of antenna, (2) the body without lateral processes or knobs, (3) the second segment of exopod of leg 1 bearing with one spine, (4) the armature of antennule being 3, 16, 4, 2 + 1 aesthetasc, and 4 + 1 aesthetasc, (5) the caudal ramus with three terminal setae, and (6) the tip of mandible with unilateral spinules. The three records of Anchimolgus species seem to have larger body size/appendages and more digitiform lobes on the convex side of the mandible than those from the Great Barrier Reef, New Caledonia, and Moluccas. Until now, 18 species of symbiotic copepods have been known to be associated with Galaxea corals.