OSTRACOD RESEARCH

at the Lake Biwa Museum, Japan


Robin James Smith

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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 (carapace), Meisch 2000 (carapace and appendages).
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 (carapace and appendages).
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 (carapace and appendages).
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.


Key characters Cypria exsculptaCypria konishiiCypria matzkeae
Carapace - ventral valve overlapLeft valve overlaps right along ventral margin
Carapace - margin structure - septaNo septa present
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 striatedSurface smoothSurface striated
Carapace - width/length ratio (w/l)Less than 0.4 (slender species)
Antennule - segmentsSeven moveable segments
Antennule - Rome organRome organ present
Antenna - exopoditeExopodite reduced to small segment
Antenna - swimming setaeSwimming setae very long, reaching well beyond end of claws Swimming setae reduced, not reaching to end of claws Swimming setae very long, reaching well beyond end of claws
Fifth limb - morphologyMaxilliped; Male palps with moveable terminal hooks
Sixth limb - segmentsFive segments
Sixth limb - setae on first segmentNo setae
Sixth limb - h3 seta on final segmentH3 seta short; much shorter than half length of claw
Seventh LimbCleaning limb, with three setae at end
Seventh Limb - segmentsFour segments
Seventh Limb - first segmentThree setae
Caudal ramusElongate ramus with two claws and two setae
Caudal ramus - attachmentWith no loops