The egg of Platycnemididae

A final renewal day is September 20, 2003.


  Two species of Platycnemididae inhabit Kinki area.

How to obtaining eggs : The female which lays eggs is found. Then, the plant that it lays eggs is collected. Copera annulata lays eggs in the moist filter paper.


1. Platycnemis foliacea sasakii Asahina

Size: Right after laying; head diameter; 1.02mm, a short diameter 0.20mm. Just before hatching; head diameter 1.14mm, a short diameter; 0.19mm. Duration of egg :  The shortest duration; 10days. Average duration; 11days. It lays eggs with Platycnemis foliacea sasakii in the stem of the aquatic plant (such as Hydrilla verticillata and Egeria densa) growing in the slow flow.

Figure2-1: After laying, the 10th day

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2. Copera annulata (Selys)

Size: Right after laying; head diameter; 1.18mm, a short diameter 0.19mm. Just before hatching; head diameter 1.30mm, a short diameter; 0.24mm. Duration of egg :  The shortest duration; 8days. Average duration; 9days. Copera annulata has a long projection around anterior pole of the egg. Copera annulata lays eggs in the leafstalk of water lily, the stem of yellow pond lily, and so on.

Figure2-2: After laying, the 9th day


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