Ostracod Research at the Lake Biwa Museum, Japan

Robin James Smith

Genus Heterocypris Claus, 1892

Superfamily: Cypridoidea Baird, 1845
Family: Cyprididae Baird, 1845
Subfamily: Cyprinotinae Bronstein, 1947

Four species have been reported from Japan:

1. Heterocypris auricularis Zhai & Zhao, 2014

Figures in: Zhai & Zhao 2014; Okubo 2004 (as Heterocypris sansanukiensis Okubo, 2004 nomen nudum).
Habitat: Rice fields in Japan. Dead arm of a river in Inner Mongolia.
Mode of life: Nektobenthic (swimmer).
Reproduction mode: Sexual.
Known distribution: Kagawa Prefecture (Okubo 2004). Elsewhere, Inner Mongolia, China (Zhai & Zhao, 2014).
References:
⚬ Okubo, I. 2004. Nihon tansui san kaimijinko rui ni tsuite. Kabushikigaisha Sanmon Insatsusho, Okayama, Japan, 72pp. [In Japanese, privately published].
⚬ Zhai, D. & Zhao, W. 2014. On some recent non-marine ostracods from northern China, with description of one new species. Crustaceana, 87, 985-1026.

2. Heterocypris barbara (Gauthier & Brehm, 1928)

Figures in: Gauthier & Brehm 1928; Okubo 1973 (as Heterocypris takedai); Okubo & Ida 1989 (as Heterocypris bulgarica); Meisch 2000; Okubo 2004 (as Heterocypris bulgarica).
Habitat: Japan, rice fields (Okubo 2004). Elsewhere, both temporary and permanent water bodies, inlcuding lakes (Meisch 2000).
Mode of life: Nektobenthic (swimmer).
Reproduction mode: Okubo & Ida (1989) noted males, but Okubo (2004) states that males don't exist. Elsewhere, occasionally sexual (Meisch 2000).
Known distribution: Tokyo (Okubo 1973, as Heterocypris takedai); Gunma Prefecture (Okubo 1990, as Heterocypris bulgarica). Elsewhere, the circum-Mediterranean region (see review in Meisch 2000).
Notes: Heterocypris takedai and Heterocypris bulgarica are junior synonyms of Heterocypris barbara.
References:
⚬ Gauthier, H. & Brehm, V. 1928. Ostracodes et cladoceres de l'Algérie et de la Tunisie. Bulletin de la Société d'Histoire Naturelle de l'Afrique du Nord, 19, 114-121.
⚬ 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.
⚬ Okubo, I. 1973a. Heterocypris takedai sp. nov. (Ostracoda, Cyprididae) from Japan. Annotationes Zoologicae Japonenses, 46, 85-89.
⚬ Okubo, I. 1990. Sixteen species of freshwater Ostracoda from Japan. Bulletin of the Biogeographical Society of Japan, 45, 39-50.
⚬ Okubo, I. 2004. Nihon tansui san kaimijinko rui ni tsuite. Kabushikigaisha Sanmon Insatsusho, Okayama, Japan, 72pp. [In Japanese, privately published].
⚬ Okubo, I. & Ida, K. 1989. Freshwater Ostracoda from Gunma Prefecture, Japan (In Japanese). Bulletin of the Biogeographical Society of Japan, 44, 105-107.

3. Heterocypris incongruens (Ramdohr, 1808)

Left side view of a female Heterocypris incongruens, length 1.8mm.

External view of a female left valve of Heterocypris incongruens, length 1660 microns.

External view of a female right valve of Heterocypris incongruens, length 1630 microns.

Additional figures in: Okubo 1972; Meisch 2000.
Habitat: Rice fields, puddles.
Mode of life: Nektobenthic (swimmer).
Reproduction mode: Asexual in Japan. Sexual populations known from some areas in Europe, Turkey and North Africa (Meisch 2000).
Known distribution: Shiga Prefecture (Smith et al 2011); Okayama Prefecture; Shimane Prefecture; Tokyo (Okubo 1972); Chiba Prefecture (Okubo 1975); Gunma Prefecture (Okubo & Ida 1989); Hokkaido (Hiruta & Smith 2001); Kagoshima Prefecture (Smith & Kamiya 2006); Hiroshima Prefecture; Yamaguchi Prefecture; Okinawa (Broodbakker 1988); Shizuoka Prefecture (Tanaka et al. 2015). Found globally, a cosmopolitan species (Meisch 2000).
References:
⚬ Broodbakker, N. W. 1988. Ecology and distribution of groundwater Crustacea and freshwater Ostracoda in SW Honshu and the Nansei Islands, Japan. Verlagen en Technische Gegevens Institute voor Taxonomische Zoologie, 53, 1-21.
⚬ 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.
⚬ Okubo, I. 1972. Freshwater Ostracoda from Japan, IV. Heterocypris incongruens (Ramdohr, 1808). Review of Shujitsu Junior College, Okayama, 1, 73-84.
⚬ Okubo, I. 1973. Heterocypris takedai sp. nov. (Ostracoda, Cyprididae) from Japan. Annotationes Zoologicae Japonenses, 46, 85-89.
⚬ Okubo, I. 1975. Studies on Ostracoda in fishponds - I. Two species in fishponds of the Chiba Prefectural Freshwater Fisheries Experimental Station. Bulletin of the Japanese Society of Scientific Fisheries, 41, 155-165.
⚬ Okubo, I. 1990. Seven new species of freshwater Ostracoda from Japan. Researches on Crustacea, 19, 1-12.
⚬ Okubo, I. 2004. Nihon tansui san kaimijinko rui ni tsuite. Kabushikigaisha Sanmon Insatsusho, Okayama, Japan, 72pp. [In Japanese, privately published].
⚬ Okubo, I. and K. Ida 1989. Freshwater Ostracoda from Gunma Prefecture, Japan (In Japanese). Bulletin of the Biogeographical Society of Japan, 44, 105-107.
⚬ Smith, R. J. & Kamiya, T. 2006. Six new species of fresh and brackish water ostracods (Crustacea) from Yakushima, Southern Japan. Hydrobiologia, 559, 331-355.
⚬ Smith, R. J., Janz, H. & Okubo, I. 2011. Recent Cyprididae and Ilyocyprididae (Crustacea: Ostracoda) from Lake Biwa, Japan, including a summary of the lake's ostracod fauna. Zootaxa, 2874, 1-37.
⚬ Tanaka, H., Kotorii, H., Yokozawa, K., Wakabayashi, F., Kimoto, K. & Sano, K. 2015. Distribution and occurrence of freshwater Ostracoda (Crustacea) from southwest region of Mt. Fuji. TAXA, Proceedings of the Japanese Society of Systematic Zoology, 38, 26-41. [In Japanese with English abstract.]

4. Heterocypris savatenalintonae Smith & Chang, 2020

Left side view of a male Heterocypris savatenalintonae, length about 1.1 mm.

External view of a female left valve of Heterocypris savatenalintonae, length 1358 microns.

External view of a female right valve of Heterocypris savatenalintonae, length 1289 microns.

External view of a male left valve of Heterocypris savatenalintonae, length 1154 microns.

External view of a male right valve of Heterocypris savatenalintonae, length 1110 microns.

The male sexual organ of Heterocypris savatenalintonae, length 306 microns.

Additional figures in: Okubo 2004 (as Heterocypris rotundata); Smith & Chang 2020.
Habitat: Rice fields.
Mode of life: Nektobenthic (swimmer).
Reproductive mode: Sexual.
Known distribution: Shiga Prefecture Japan. May also be present in China (Smith & Chang 2020).
References:
⚬ Okubo, I. 2004. Nihon tansui san kaimijinko rui ni tsuite. Kabushikigaisha Sanmon Insatsusho, Okayama, Japan, 72pp. [In Japanese, privately published].
⚬ Smith, R. J. & Chang, C. Y. 2020. Taxonomic assessments of some Cyprinotinae Bronstein, 1947 species (Crustacea: Ostracoda) from Japanese and Korean rice fields, including (re-) descriptions of six species and a review of the type species of the subfamily. Zootaxa, 4795 (1), 001-069.

5. Heterocypris spadix Munakata et al., 2021

Figures in: Munakata et al., 2021.
Habitat: Brackish creek.
Mode of life: Nektobenthic (swimmer).
Reproduction mode: Asexual.
Known distribution: Okinawa (Munakata et al., 2021).
References:
⚬ Munakata, M., Tanaka, H. & Kakui, K. 2021. Heterocypris spadix sp. nov. (Crustacea: Ostracoda: Cypridoidea) from Japan, with information on its reproductive mode. Zoological Science, 38 (3).