at the Lake Biwa Museum, Japan

Robin James Smith

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Genus Potamocypris Brady, 1870

Superfamily: Cypridoidea Baird, 1845
Family: Cyprididae Baird, 1845
Subfamily: Cypridopsinae Kaufmann, 1900

Two species have been reported from Japan:

1. Potamocypris mastigophora (Methuen, 1910)

Figures in: Okubo 1976 (carapace and appendages, as Potamocypris producta); Okubo 2004 (carapace, as Potamocypris producta); Meisch 1985 (carapace and appendages, as Potamocypris producta).
Habitat: In Japan, eel culture ponds and pools of water (Okubo 1976; 2004), and a river estuary (Ikeya & Hanai 1982). Elsewhere, rice fields (Petkovski 1964).
Mode of life: Nektobenthic (swimmer).
Reproductive mode: Asexual in Japan. Males reported from South Africa (Sars 1924).
Known distribution: Chiba and Shizuoka Prefectures (Okubo 1976; Ikeya & Hanai 1982 both as Potamocypris producta). Elsewhere, reported from Africa (see references in Martens 1984); Macedonia (Petkovski 1964 as Potamocypris producta); France (Meisch et al. 1990 as Potamocypris producta); Israel (Lerner-Seggev 1968 as Potamocypris producta); Korea (Kim and Min 1991 as Potamocypris producta).

Ikeya, N. & Hanai, T. 1982. Ecology of Recent ostracods in the Hamana-ko region, the Pacific coast of Japan. University Museum of the University of Tokyo, Bulletin 20, 15-59.

Kim, W. & Min, G.. S. 1991. Redescription of four recent freshwater ostracods (Crustacea: Ostracoda) from Korea. Korean Journal of Zoology, 34, 307-322.

Lerner-Seggev, R. 1968. The fauna of Ostracoda in Lake Tiberias. Israel Journal of Zoology, 17, 117-143.

Martens, K. 1984. Annotated checklist of non-marine ostracods Crustacea, Ostracoda from African inland waters. Musee Royal de l'Afrique Centrale Tervuren - Belgique, Documentation Zoologique N20, 1-51.

Meisch, C. 1985. Revision of the Recent West European species of the genus Potamocypris (Crustacea, Ostracoda). Part II. Species with long swimming setae on the second atennae. Travaux Scientifiques de Musée d'Histoire Naturelle de Luxembourg, 6, 1-95.

Meisch, C., Wouters, K. & Martens, K. 1990. Liste annotée des Ostracodes actuels nonmarins trouvés en France (Crustacea, Ostracoda). Travaux Scientifiques du Musee National d'Histoire Naturelle de Luxembourg, 15, 1-62.

Okubo, I. 1976. Potamocypris producta (Sars, 1924) from Japan. Researches on Crustacea, 7, 52-56.

Okubo, I. 2004. Nihon tansui san kaimijinko rui ni tsuite. Kabushikigaisha Sanmon Insatsusho, Okayama, Japan, 72pp. [In Japanese, privately published].

Petkovski, T. K. 1964. Bemerkenswerte Entomostraken aus Jugoslavien. Musei Macedonici Scientiarum Naturalium, 7, 147-182.

Sars, G. O. 1924.The Fresh-water Entomostraca of the Cape Province (Union of South Africa). Part II: Ostracoda. Annals of the South African Museum, 20, 105-177.

2. Potamocypris sudzukii Okubo & Terauchi, 1992

Figures in: Okubo & Terauchi 1992 (carapace); Okubo 2004 (carapace) (N.B. one specimen, 783, figured in Okubo 2004 is listed as a juvenile in Okubo & Terauchi 1992).
Habitat: Ponds and rice fields (Okubo 2004).
Mode of life: Nektobenthic (swimmer).
Reproductive mode: Asexual.
Known distribution: Okinawa (Okubo & Terauchi 1992).

Okubo, I. 2004. Nihon tansui san kaimijinko rui ni tsuite. Kabushikigaisha Sanmon Insatsusho, Okayama, Japan, 72pp. [In Japanese, privately published].

Okubo, I. & Terauchi, M. 1992. Freshwater Ostracoda from the Southwestern Islands of Japan. Proceedings of the Japanese Society for Systematic Zoology, 46, 101-108.

Key characters Potamocypris mastigophora & Potamocypris sudzukii
Carapace - ventral valve overlapRight valve overlaps left 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 pitted
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 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 ramusReduced ramus with two setae
Caudal ramus - attachmentWith no caudal ramus attachment