at the Lake Biwa Museum, Japan

Robin James Smith

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Genus Cypretta Varva, 1895

Superfamily: Cypridoidea Baird, 1845
Family: Cyprididae Baird, 1845
Subfamily: Cyprettinae Hartmann, 1971

One species has been reported from Japan:

1. Cypretta seurati Gauthier, 1929

Dorsal views of two female Cypretta seurati, length 0.68 mm. This species is very globular. In this species, like most of the genus Cypretta, the right valve overlaps the left (a handful of species in the genus have the opposite overlap).

External view of a left valve of a female Cypretta seurati. Length 673 microns. The septa can be clearly seen along the anterior margin.

External view of a right valve of a female Cypretta seurati. Length 686 microns. The surface is covered in small, shallow pits (punctate).

Additional figures in: Okubo 1973 (carapace and appendages); Okubo 2004 (carapace); Smith & Kamiya 2006 (carapace); Meisch et al. 2007 (carapace); Smith et al. 2011 (carapace).
Habitat: Rice fields, ponds (Okubo 1973), freshwater rockpools (Smith & Kamiya 2006), and Lake Biwa (Smith et al. 2011).
Mode of life: Nektobenthic (swimmer).
Reproduction mode: Asexual, males unknown.
Known distribution: Shiga, Okayama, Fukuoka, Miyazaki, Gunma, Kagoshima, and Shizuoka Prefectures (Okubo 1973; Okubo & Ida 1989; Smith & Kamiya 2006; Smith et al. 2011; Tanaka et al. 2015). Outside Japan widespread in lower latitudes (Meisch et al. 2007).

Meisch, C., Mary-Sasal, N., Colin, J-P., & Wouters, K. 2007. Freshwater Ostracoda (Crustacea) collected from the islands of Futuna and Wallis, Pacific Ocean, with a checklist of the non-marine Ostracoda of the Pacific Islands. Bulletin de la Société des naturalistes luxembourgeois, 108, 89-103.

Okubo, I. 1973. Cypretta seurati Gauthier, 1929, from Japan (Ostracoda, Cyprididae). Proceedings of the Japanese Society of Systematic Zoology, 9, 1-6.

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.

Smith, R. J. & Kamiya, T. 2006. Six new species of fresh and brackish water ostracods (Crustacea) from Yakushima, Southern Japan. Hydrobiologia, 559, 331-355.

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.]

Key characters Cypretta seurati
Carapace - ventral valve overlapRight valve overlaps left along ventral margin
Carapace - margin structure - septaSepta present only along anterior margin
Carapace - margin structure - ridges on inner calcified lamellaNo ridges
Carapace - dorsal view - female with brood pouchBrood pouch not visible
Carapace - lateral view - ventral marginVentral margin approximately straight to concave
Carapace - lateral view - valve heightLeft and right valves similar height
Carapace - internal viewAnterior calcified inner lamella wider than posterior one
Carapace - ornamentation - denticlesNo denticles near ventral margin
Carapace - ornamentation - sulcusNo sulcus
Carapace - ornamentation - surfaceSurface pitted
Carapace - width/length ratio (w/l)Greater than 0.7 (rounded species)
Antennule - segmentsSeven moveable segments
Antennule - Rome organRome organ present
Antenna - exopoditeExopodite reduced to small segment
Antenna - swimming setaeSwimming setae long, reaching to about end of claws
Fifth limb - morphologyMaxilliped
Sixth limb - segmentsFive segments
Sixth limb - setae on first segmentOne seta
Sixth limb - h3 seta on final segmentH3 seta short; much shorter than half length of claw
Seventh LimbCleaning limb, with a pincer at end
Seventh Limb - segmentsThree segments
Seventh Limb - first segmentThree setae
Caudal ramusElongate ramus with two claws and two setae*
Caudal ramus - attachmentWith no loops

* Although the ramus is elongate, it is small and delicate.