The egg of  Gomphidae

A final renewal day is September 23, 2003.


  Gomphidae with the record in Kinki area are 22 kinds.  After 2000 years, I haven't been observing 3 species of Gomphidae yet. Those are Stylurus nagoyanus, Stylurus annulatus and Lanthus fujiacus. The egg of Gomphidae is often different from other families. For example, a regular pattern is seen by the shell of the egg. There is an egg which has the gelatine-shaped material to develop into the form which changed.
When the egg of the dragonfly begins embryonic development, both a head diameter and a short diameter are growing big. However, length (head diameter) hardly changes even if embryonic development proceeds in Davidius and Trigomphus  However, an egg is roundish because width (a short diameter) is widened.  I did all observations and photography. My friend collected some species of eggs.

How to obtaining eggs : It stands in the air, and the female of Onychogomphus viridicostus and Nihonogomphus viridis drops the lump of the egg which consists of many eggs to the surface of the water. Before landing on the water, an egg caught me.
It lays eggs with Sinictinogomphus clavatus on the surface of the plant in the surface of the water and so on. I collected those plants after I ascertained laying.  The female of Asiagomphus pryeri and Gomphus postocularis saves an egg in the waterfront in the valvula valvae. I caught such a female.  Other kinds of female lay eggs when a valvula valvae is soaked in water. The female which lays eggs, or the female which matured is good.


Figure7-1: The egg of  Gomphidae (They are 19 species. It hasn't been collected three species yet.)

An observation record before 1999 is contained in the following data, too

1.  Anisogomphus maacki (Selys)

Size: Right after laying; head diameter; 0.49mm, a short diameter 0.31mm. Just before hatching; head diameter 0.56mm, a short diameter; 0.39mm. Duration of egg : The shortest duration; 10days. Average duration; 15days.Photo : After laying, the 10th day

 

2.  Stylurus oculatus (Asahina)

Size: Right after laying; head diameter; 0.45mm, a short diameter 0.31mm. Just before hatching; head diameter 0.47mm, a short diameter; 0.36mm. Duration of egg :  The shortest duration; 9days. Average duration; 9days. Photo : After laying, the 9th day   A female flies to the lake shore in the early morning and the evening. Then, it stops on the sand, and an egg is discharged. After that, it laid eggs in the waterfront and the wave.

 

3.  Stylurus nagoyanus (Asahina) 

Size: Right after laying; head diameter; 0.54mm, a short diameter 0.31mm. Just before hatching; head diameter 0.54mm, a short diameter; 0.41mm. Duration of egg : The shortest duration; 11days. Average duration; 13days. An egg comes in under water, and jelly-shaped material in the neighborhood of the egg spreads out when the strong power such as a current is added. Then, it sticks strongly, too.

 

4. Stylurus annulatus (Djakonov)

 I haven't collected an egg yet

 

5.  Gomphus postocularis Selys

Size: Right after laying; head diameter; 0.55mm, a short diameter 0.34mm. Just before hatching; head diameter 0.64mm, a short diameter; 0.42mm. Duration of egg :  The shortest duration; 9days. Average duration; 10days. Photo : After laying, the 7th day

 

6.   Asiagomphus melaenops (Selys)

Size: Right after laying; head diameter; 0.56mm, a short diameter 0.36mm. Just before hatching; head diameter 0.60mm, a short diameter; 0.43mm. Duration of egg :  The shortest duration; 9days. Average duration; 13days. Photo : After laying, the 8th day

 

7. Asiagomphus pryeri (Selys)

Size: Right after laying; head diameter; 0.56mm, a short diameter 0.29mm. Just before hatching; head diameter 0.58mm, a short diameter; 0.37mm. Duration of egg : The shortest duration; 9days. Average duration; 9days. Photo : After laying, the 10th day

 

8.  Nihonogomphus viridis Oguma

Size: Right after laying; head diameter; 0.51mm, a short diameter 0.45mm. Just before hatching; head diameter 0.56mm, a short diameter; 0.51mm. Duration of egg :  The shortest duration; 11days. Average duration; 14days. Photo : After laying, the 10th day

 

9.  Onychogomphus viridicostus (Oguma)

Size: Right after laying; head diameter; 0.47mm, a short diameter 0.40mm. Just before hatching; head diameter 0.54mm, a short diameter; 0.47mm. Duration of egg : The shortest duration; 9days. Average duration; 10days. Photo : After laying, the 10th day

 

10.  Trigomphus melampus (Selys)

Size: Right after laying; head diameter; 0.63mm, a short diameter 0.35mm. Just before hatching; head diameter 0.63mm, a short diameter; 0.43mm. Duration of egg :  The shortest duration; 15days. Average duration; 21days. Photo : After laying, the 16th day

  

11. Trigomphus interruptus (Selys)

Size: Right after laying; head diameter; 0.57mm, a short diameter 0.35mm. Just before hatching; head diameter 0.58mm, a short diameter; 0.43mm. Duration of egg :  The shortest duration; 14days. Only less than half hatched. Photo : After laying, the 12th day

 

12. Trigomphus ogumai Asahina

Size: Right after laying; head diameter; 0.59mm, a short diameter 0.37mm. Just before hatching; head diameter 0.59mm, a short diameter; 0.43mm. Duration of egg : The shortest duration; 14days. Average duration; 22days. Photo : After laying, the 14th day

 

13.  Trigomphus citimus tabei Asahina

Size: Right after laying; head diameter; 0.68mm, a short diameter 0.38mm. Just before hatching; head diameter 0.67mm, a short diameter; 0.46mm. Duration of egg :  The shortest duration; 17days. Average duration; 19days. Photo : After laying, the 15th day

 

14.  Davidius nanus (Selys)

Size: Right after laying; head diameter; 0.66mm, a short diameter 0.32mm. Just before hatching; head diameter 0.63mm, a short diameter; 0.38mm. Duration of egg :  The shortest duration; 17days. Average duration; 19days. Photo : After laying, the 15th day

 

15.  Davidius fujiama Fraser

Size: Right after laying; head diameter; 0.71mm, a short diameter 0.39mm. Just before hatching; head diameter 0.67mm, a short diameter; 0.41mm. Photo : After laying, the 22nd day The egg put on the inside didn't hatch.

 

16.  Davidius moiwanus taruii Asahina et Inoue

Size: Right after laying; head diameter; 0.64mm, a short diameter 0.33mm. Just before hatching; head diameter 0.62mm, a short diameter; 0.42mm. Duration of egg : The shortest duration; 17days. Only less than half hatched. Photo : After laying, the 17th day

 

17.  Lanthus fujiacus (Fraser)

 I haven't collected an egg yet

 

18.  Sinogomphus flavolimbatus (Oguma)

Size: Right after laying; head diameter; 0.64mm, a short diameter 0.29mm. Just before hatching; head diameter 0.59mm, a short diameter; 0.37mm. Duration of egg :  The shortest duration; 16days. Average duration; 18days. Photo : After laying, the 16th day

 

19. Stylogomphus suzukii (Oguma)

Size: Right after laying; head diameter; 0.59mm, a short diameter 0.27mm. Just before hatching; head diameter 0.56mm, a short diameter; 0.34mm. Duration of egg : The shortest duration; 12days. Average duration; 12days. Photo : After laying, the 12th day

 

20.   Sieboldius albardae Selys

Size: Right after laying; head diameter; 0.77mm, a short diameter 0.43mm. Just before hatching; head diameter 0.83mm, a short diameter; 0.52mm. Duration of egg :  The shortest duration; 11days. Average duration; 12days. Photo : After laying, the 10th day

 

21. Sinictinogomphus clavatus (Fabricius)

Size: Right after laying; head diameter; 0.81mm, a short diameter 0.35mm. Just before hatching; head diameter 0.81mm, a short diameter; 0.43mm. Duration of egg :  The shortest duration; 7days. Average duration; 10days. Photo : After laying, the 7th day

 

22. Ictinogomphus pertinax (Selys)

Size: Right after laying; head diameter; 0.75mm, a short diameter 0.40mm. Just before hatching; head diameter 0.78mm, a short diameter; 0.47mm. Duration of egg :  The shortest duration; 8days. Average duration; 8days. Photo : After laying, the 9th day