Nonmarine Ostracoda from Jeju Island, South Korea

Abstract

An extensive faunistic survey on brackish and freshwater ostracods on Jeju Island, South Korea, yielded 26 species, including two new species belonging to the genera Cyclocypris and Cypretta. In addition to the two new species, nine are new to the Korean fauna: Bradleytriebella tuberculata (Hartmann, 1964), Strandesia flavescens Klie, 1932, Potamocypris variegata (Brady & Norman, 1889), Heterocypris salina (Brady, 1868), Stenocypris hirutai Smith & Kamiya, 2006, Ishizakiella miurensis (Hanai, 1957), Terrestricythere ivanovae Schornikov, 1969, Limnocythere sp. and Tanycypris sp. The presence of the new Cyclocypris species and T. ivanovae on a subtropical island is unusual as both genera are typically found in cooler climates. Both were recovered from the entrance of a cave, which may indicate that the cave system or connecting groundwater maybe a refuge for these two species. The Tanycypris species is also known from Germany, where it is considered to be an alien species. The Limnocythere species belongs to the stationis-group, which consists of another 8 species, and is probably undescribed. A lack of males hinders its description, but its presence in Korea is significant including the record herein, seven of the group inhabit Northeast Asia, indicating the group may have originated in this region. The other new records were all previously known from Northeast Asia, with the exception of Potamocypris variegata. This to the Korean fauna: Bradleytriebella tuberculata (Hartmann, 1964), Strandesia flavescens Klie, 1932, Potamocypris variegata (Brady & Norman, 1889), Heterocypris salina (Brady, 1868), Stenocypris hirutai Smith & Kamiya, 2006, Ishizakiella miurensis (Hanai, 1957), Terrestricythere ivanovae Schornikov, 1969, Limnocythere sp. and Tanycypris sp. The presence of the new Cyclocypris species and T. ivanovae on a subtropical island is unusual as both genera are typically found in cooler climates. Both were recovered from the entrance of a cave, which may indicate that the cave system or connecting groundwater maybe a refuge for these two species. The Tanycypris species is also known from Germany, where it is considered to be an alien species. The Limnocythere species belongs to the stationis-group, which consists of another 8 species, and is probably undescribed. A lack of males hinders its description, but its presence in Korea is significant including the record herein, seven of the group inhabit Northeast Asia, indicating the group may have originated in this region. The other new records were all previously known from Northeast Asia, with the exception of Potamocypris variegata. This