• Animal Systematics, Evolution and Diversity
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• v.35 no.2
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• pp.49-56
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• 2019

A new marine halacarid species of the genus Agauopsis Viets, 1927 (Acari: Halacaridae) is recorded from Jeju Island, Korea. Agauopsis tetrasetosa n. sp. belongs to the microrhyncha group in sharing one ventral and three ventromedial spines on tibia of leg I, of which two ventromedial ones are adjacent to each other, with its 20 congeneric members. Agauopsis tetrasetosa n. sp. is most similar to A. miliaris Bartsch, 2005 and A. similis Bartsch, 1979 in sharing the similar chaetotaxy of legs I-IV, positions of the second and fourth dorsal setae, and non 'H'- or 'M'-shaped costae on anterior dorsal plate. However, the new species is distinguished from them by four pairs of perigenital setae in female, the relatively anterior location of gland pores on posterior dorsal plate, and three ventral spines on the tibia of leg II. We describe the new species herein, with detailed illustrations under a differential interference contrast microscope. We also make some brief comments on the affinities between the congeneric species of the microrhyncha group and the new species, based on a tabular key to species of the group.