at the Lake Biwa Museum, Japan

Robin James Smith

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Genus Chlamydotheca Saussure, 1858

Superfamily: Cypridoidea Baird, 1845
Family: Cyprididae Baird, 1845
Subfamily: Cypridinae Baird, 1845

One species has been reported from Japan:

1. Chlamydotheca arcuata (Sars, 1901)

External view of female left valve, length 2800 microns.

External view of female right valve, length 2902 microns.

Additional figures in: Sars 1901 (carapace and caudal ramus), Furtos 1933 (carapace, maxillula, seventh limb), Okubo 2004 (carapace), Smith & Delorme 2010 (carapace), Diaz & Lopretta 2011 (carapace & appendages).
Habitat: In Japan, only reported from a water lily pond in a botanical garden (Okubo 2004). Elsewhere reported from a river (Davis 1980), warm springs, streams, marshes, margins of lakes (Forester 1991), temporary ponds (Diaz & Lopretta 2011), and a canal (Furtos 1933).
Mode of life: Nektobenthic (swimmer).
Reproductive mode: Asexual.
Known distribution: Shiga Prefecture (Okubo 2004). Elsewhere, Brazil (Sars 1901), Paraguay (Daday 1905), Argentina (Diaz & Lopretto 2011), Mexico (Forester 1991), and USA (Furtos 1933; Davis 1980; Forester 1991).
Notes: This species shows a wide size range, from about 2 mm (Diaz & Lopretta 2011) to 3 mm in length (Forester 1991).

Daday, E. 1905. Untersuchungen über die Süsswasser-Mikrofauna Paraguay. Zoologica, 18, 1-374.

Davis, J. R. 1980. Species composition and diversity of benthic macroinvertebrates of Lower Deveil's River, Texas. The Southwestern Naturalist, 25, 379-384.

Diaz, A. R. & Lopretto, E. C. 2011. The genus Chlamydotheca Saussure (Crustacea: Ostracods) in northeastern Argentina. Nauplius, 19, 97-107.

Furtos, N. 1933. The Ostracoda of Ohio. Ohio Biological Survey, 5, 413-524.

Forester, R. M. 1991. Ostracode assemblages from springs in the Western United States: implications for paleohydrology. Memoirs of the Entomological Society of Canada, 155, 181-201.

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

Sars, G. O. 1901. Contributions to the knowledge of the freshwater Entomostraca of South America. Part 2. Copepods - Ostracods. Archiv Mathematik og Naturvidenskab, 24, 1-46.

Smith, A. & Delorme, D. 2010. Ostracoda. In: Ecology and Classification of North American Freshwater Invertebrates. Elsevier Inc.

Key characters Chlamydotheca arcuata
Carapace - ventral valve overlapRight valve overlaps left along ventral margin
Carapace - margin structure - septaNo septa present
Carapace - margin structure - ridges on inner calcified lamellaOn left valve and right valve
Carapace - dorsal view - female with brood pouchBrood pouch not visible
Carapace - lateral view - ventral marginVentral margin convex
Carapace - lateral view - valve heightLeft and right valves similar height
Carapace - internal viewPosterior calcified inner lamella wider than anterior one
Carapace - ornamentation - denticlesNo denticles near ventral margin
Carapace - ornamentation - sulcusNo sulcus
Carapace - ornamentation - surfaceSurface smooth
Carapace - width/length ratio (w/l)Between 0.4 and 0.7 (medium 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 segmentTwo setae
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