An unrecorded species of the genus Isobactrus (Acari, Halacaridae) from Korea

Abstract

We discovered a halacarid mite species, Isobactrus tuberculatus Abé, 1996 in marine plastic debris, which was washed up on the coast of Jeju Island, Korea. Isobactrus tuberculatus was described from Hokkaido, Japan, and is characterized by the following features: the presence of tuberculate on the membranous cuticle between the anterior and posterior dorsal plates, the absence of a border of the ventral shield with small epimeral plates I and II, the position of the third perigenital seta at the posterior edge of the genital opening in females, tibia II with one bipectinate seta, and each tibia of legs III and IV with five setae. Korean specimens agree well with the original description from Japan. However, they showed two small differences morphologically: the distance between the anterior and posterior dorsal plates is shorter in Korean specimens than in Japanese specimens, and the location of dorsal seta-2 is closer to the anterior dorsal plate in Korean specimens.