Comparative morphology of Zenker´s organ in freshwater Cypridoidea (Ostracoda, Crustacea) from Argentina

DÍAZ A.R.; BALLENT, SARA.; LOPRETTO, E.C.

Brasilia, Brasil

Simposio; XVI ISO (International Symposium Ostracoda); 2009

IRGO

The Zenker?s organ (distal chitinous part of the vas deferens) has been described for five species of Argentinian non-marine ostracods. Samples were taken from lentic waters from the northeastern (Misiones province; 25° 41? S ? 54° 26? W); northwestern (Catamarca province, 27° 40? 56.8? S ? 68° 26? 40.6? W) and the eastern (Buenos Aires province 35º 05? S ? 57º 31? W) of Argentina. Specimens were dissected under stereo-microscope in glycerine and ZO were laid into NaClO 5% to remove all muscle and epithelial tissue covering the chitinous part of the organ. After some minutes ZO were washed in distilled water and mounted and photographed at Servicio de Microscopía Electrónica de Barrido of the Facultad de Ciencias Naturales y Museo (University of La Plata, Argentina) in a JEOL JSM 6360 LV scanning electron microscope. In small species it was only possible to obtain digital photographs. Five species of the superfamily Cypridoidea were analized: Candona Baird and Cypria Zenker (Candonidae), Cypriconcha Sars, Eucypris Vávra and Plesiocypridopsis Rome (Cyprididae). All ZO analized have the same chitinous pattern of whorls and spines although the range of size varies from 0.125mm in Plesiocypridopsis sp. to 0.7mm in Cypriconcha sp., the number of chitinous whorls varies between 5 in Candona sp. and Cypria sp. to 35 in Cypriconcha sp.; the braces of ends plates varies between 14/15 in Plesiocypridopsis sp. and 37 in Candona sp.