Ostracod Research at the Lake Biwa Museum, Japan

Robin James Smith

Genus Darwinula Brady & Robertson, 1885

Superfamily: Darwinuloidea Brady & Robertson, 1885
Family: Darwinulidae Brady & Robertson, 1885

One species has been reported from Japan:

1. Darwinula stevensoni (Brady & Robertson, 1870)

Scanning electron microscopy (SEM) image of the ventral view (underside) of a female Darwinula stevensoni, length 0.8 mm. The right valve is larger than the left, and overlaps the left along the ventral margin when the carapace is closed. Most other genera have an opposite overlap.

Right lateral view of a female Darwinula stevensoni, length 0.8 mm. Note the three eggs in the brood chamber towards the rear.

External view of female left valve, length 693 microns.

External view of female right valve, length 710 microns.

Additional figures in: Smith & Kamiya 2008; Okubo 2001.
Habitat: Found in a wide variety of habitats. In Japan reported from lakes, ponds, a rice field, and spring runoff.
Mode of life: Benthic.
Reproductive mode: Asexual, males unknown.
Known distribution: Shiga Prefecture (Okubo 2001; Smith & Kamiya 2008; Smith & Janz 2009); Kagoshima Prefecture (Smith & Kamiya 2006); Shizuoka Prefecture (Tanaka et al. 2015), Akita Prefecture (Ishii et al. 2017). A cosmopolitan species, found globally.
⚬ Ishii, T., Suzuki, A. & Tanaka, H. 2017. First report of distribution and occurrence of freshwater Ostracoda from Lake Hachiro in Akita Prefecture. Memoirs of the Faculty of Education and Human Studies Akita University (Natural Science), 72, 1-7. [In Japanese with English abstract]
⚬ Okubo, I. 2001. Freshwater ostracod Darwinula stevensoni from Lake Biwa. Bulletin of the Biogeographical Society of Japan, 56, 39-43. [In Japanese].
⚬ Smith, R. J. & Janz, H. 2009. Recent ostracods of the superfamilies Cytheroidea and Darwinuloidea (Crustacea) from Lake Biwa, a Japanese ancient lake. Species Diversity, 14, 217-241.
⚬ 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. & Kamiya, T. 2008. The ontogeny of two species of Darwinuloidea (Ostracoda, Crustacea). Zoologischer Anzeiger, 247, 275-302.
⚬ 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.]