Xarifiid Copepods (Copepoda: Cyclopoida: Xarifiidae) Parasitic in the Coral Psammocora columna Dana, 1846 from Taiwan

SIMPLE SUMMARY: The coral reef is the crucial habitat for numerous marine creatures, and scleractinian corals are building blocks of this community. Therefore, the health condition of scleractinian corals is an essential factor for the sustainability of coral reef ecosystems. Recent studies indicate that global warming, seawater acidification as well as coral diseases are the main threats to scleractinian corals. In addition, coral endoparasites may impact the health of scleractinian corals by consuming coral tissues and potentially transferring disease pathogens. However, we have limited knowledge about the distributions of coral endoparasites across scleractinian corals. It may lead to the assessment bias on the health condition of the coral reef community due to no consideration on the impact of the interaction between corals and their endoparasites. Here, we performed an elaborate survey on a widely distributed scleractinian coral species, Psammocora columna, and discovered two new parasitic copepod species, Xarifia yanliaoensis and Xarifia magnifica. We also summarized a classification key of morphological characteristics for the identification of Xarifia copepods in Psammocora corals. The findings of this study present new records of copepod-coral relationships in the Indo-West Pacific for the biological resource database. Furthermore, these are the footstone knowledge for further studies on coral reef conservation. ABSTRACT: A comprehensive knowledge of relationships between coral and coral-associated organisms is essential for the conservation studies of the coral reef community, yet the biodiversity database of coral-inhabiting copepods remains incomplete. Here we surveyed in a widely distributed scleractinian coral, Psammocora columna Dana, 1846, and newly discovered two endoparasitic copepod species, Xarifia yanliaoensis sp. nov. and Xarifia magnifica sp. nov. These two new species are described based on specimens collected in Taiwan, and they share several common morphological characters of Xarifia copepods, i.e., region dorsal to fifth legs having three posteriorly directed processes unequally. However, X. yanliaoensis sp. nov. is distinguishable from other species by the morphology of the endopods of legs, antenna, maxilla, and maxilliped (in both genders). The morphological characters of X. magnifica sp. nov. are the endopods of legs, leg 5, and maxilliped in the male. Including the two new species described in the present work, the genus Xarifia Humes, 1960 belongs to the cyclopoid family Xarifiidae Humes, 1960 currently consists of 94 species, and eight of them live in association with the Psammocora coral. A comparison table and a key to the species of Xarifia from Psammocora corals are given herein.