Two psammobiont species of Anomalohalacarus (Acari, Halacaridae) from South Korea

Abstract

The genus Anomalohalacarus Newell, 1949, which is known to occur exclusively inhabiting sand, has not been previously reported from Korea. During a recent survey of the meiofauna from several intertidal sandy beaches in South Korea, we found both sexes of two psammobiont halacarids, Anomalohalacarus angustus sp. nov. and A. biformis Abé, 1996. Both species are similar to each other in sharing an undivided posterior dorsal plate, three and two setae on the anterior and posterior epimeral plates, respectively, three bipectinate setae on tibia IV, and four ventral setae on tarsus I. However, A. angustus sp. nov. is distinguished from A. biformis by the absence of areolae posteriorly on the anterior dorsal plate, a much more slender posterior dorsal plate, a pair of subgenital setae on the genital foramen in females, and seven branched perigenital setae on the genitoanal plate in males. The feature of branched perigenital setae in males is reported for the first time in the genus Anomalohalacarus. The Korean specimens of A. biformis agree well with the original description from Japan, except for the number of ventral bipectinate setae on tibia II. This study presents (re)descriptions of both species with detailed illustrations and provides a dichotomous key to Anomalohalacarus species, including the new species, based on morphological characters. The genus Anomalohalacarus is reported for the first time in South Korea.