Genus Cypria Zenker, 1854
Superfamily: Cypridoidea Baird, 1845
Family: Candonidae Kaufmann, 1900
Subfamily: Cyclocypridinae Kaufmann, 1900
Three species have been reported from Japan:
1. Cypria exsculpta (Fischer, 1855)
External view of a left valve of a female of Cypria exsculpta, length 712 microns.
External view of a right valve of a female of Cypria exsculpta, length 690 microns.
The surface of the carapace is covered with very fine longitudinal striations about 4-5 microns apart. Width of field of view 330 microns.
The male sexual organ of Cypria exsculpta, length 152 microns.
- Additional figures in: Hiruta & Smith 2001, Meisch 2000.
- Habitat: In Japan found in a pond and littoral zone of a lake. Elsewhere reported from springs, ponds, lakes and streams (Meisch 2000).
- Mode of life: Nektobenthic (swimmer).
- Reproductive mode: Sexual.
- Known distribution: Hokkaido (Hiruta & Smith 2001; Tanaka 2005). Elsewhere Europe, Asia and North America (Meisch 2000).
- References:
- ⚬ Hiruta, S. & Smith, R. J. 2001. Living Freshwater and Shallow marine Ostracoda in Eastern Hokkaido, Japan (Field excursion E): 107 - 125. In: Guidebook of Excursions of the 14th International Symposium on Ostracoda (ed. Ikeya, N.). Shizuoka, Japan, 147 pp.
- ⚬ Meisch, C. 2000. Freshwater Ostracoda of Western and Central Europe. In: Schwoerbel, J., Zwick, P., (Eds.), Süßwasserfauna von Mitteleuropa 8/3. Spektrum Akademischer Verlag, Heidelberg, Berlin 522 pp.
- ⚬ Tanaka, G. 2005. Morphological design and fossil record of the podocopid ostracod naupliar eye. Hydrobiologia, 538, 231-242.
2. Cypria konishii Smith & Kamiya, 2006 
External view of a left valve of a female of Cypria konishii, length 461 microns.
External view of a right valve of a female of Cypria konishii, length 450 microns.
- Additional figures in: Smith & Kamiya 2006.
- Habitat: The runoff of springs.
- Mode of life: Benthic.
- Reproductive mode: Asexual.
- Known distribution: Yakushima Island, Kagoshima Prefecture.
- References:
- ⚬ Smith, R. J. & Kamiya, T. 2006. Six new species of fresh and brackish water ostracods (Crustacea) from Yakushima, Southern Japan. Hydrobiologia, 559, 331 - 355.
3. Cypria matzkeae Smith & Janz, 2008
Left lateral view of a female of Cypria matzkeae, length approximately 0.53 mm.
External view of a left valve of a female of Cypria matzkeae, length 527 microns.
External view of a right valve of a female of Cypria matzkeae, length 516 microns.
The surface of the carapace is covered with very fine striations about 2 microns apart. Width of field of view 230 microns.
The male sexual organ of Cypria matzkeae, length 122 microns.
- Additional figures in: Smith & Janz 2008.
- Habitat: Lake Biwa, 2 to 31 meters depth.
- Mode of life: Nektobenthic (swimmer).
- Reproductive mode: Sexual.
- Known distribution: Currently only known from Lake Biwa, Shiga Prefecture.
- References:
- ⚬ Smith, R. J. & Janz, H. 2008. Recent species of the Family Candonidae (Ostracoda, Crustacea) from the ancient Lake Biwa, Central Japan. Journal of Natural History, 42, 2865-2922.