Gynacantha basiguttata

綠眼晏蜓

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Found in Asia: Bangladesh, China, Indonesia, Myanmar, Malaysia, Philippines, Peninsular Malaysia, Thailand

Genus : Gynacantha

Super-Family: AESHNOIDEA Family: AESHNIDAE

Ovipositor of a female dragonfly Gynacantha basiguttata

Ovipositor of a female dragonfly Gynacantha basiguttata

♀76mm

Ovipositor of a female Gynacantha basiguttata containing :
A) A spike like basal plate that serves as cutting blade (at rear end of segment 8)

B) A pair of thin needle like stylus at the end of Valves serving as sensor in egg positioning (at rear end of segment 9)

C) A pair of sharp anal claws that perhaps serves as anchor to stabilize the abdomen while the basal plate is cutting hole and inserting eggs into plant. (segment 10)

 

Cerci (Anal appendage)

2007-11-06 TAMAN SEMARAK

 

The family of Aeshnidae has a fully formed ovipositor which is a complicated structure covering segments 8 to 10. The ovipositor is used to insert eggs into plant tissue, mud, or other substrate.

Ovipositor of a female Gynacantha basiguttata containing :
A) A spike(
長釘) like basal plate that serves as cutting blade (rear end of segment 8)

B) A pair of thin needle like stylus that serves as sensor in egg positioning (rear end of segment 9)

C) A pair of sharp anal claws that perhaps serves as anchor to stabilize the abdomen while the basal plate is cutting hole and inserting eggs into plant. (segment 10)

 


Identification Guide to Gynacantha basiguttata

Identification Guide to
♂♀Gynacantha basiguttata
a common species of Borneo Island

Male ♂74mm

Body length = 74mm
Wing span = 102mm
Hind wing = 50mm

 

Female ♀71mm± not including 10mm superior appendage

Body length = 71mm±
appendage = 10mm±
Wing span = 108mm±
Hind wing = 52mm
±
 

lateral view
dorsal View

segment 8

S9
S10

S1

 

a pair of AURICLES (rounded ear-like)

 

Ref: Page 72 of DRAGONFLIES OF PENINSULAR MALAYSIA AND SINGAPORE by A.G. Orr


 


 

 

Another common species is  Gynacantha basiguttata (S appendages, Plate 14c, Fig. 145). It is larger than dohrni (S hw, 45-47 mm) and the male superior appendage is expanded into a distinct spatulate shape with a concentrated tuft of hairs at its tip. The inferior appendage is almost half as long as the superiors.


Without seeing the abdomen one can tell the sexing by observing the hind wings: females have a rounded hind wing base, while males have a 90 degrees angle in their hind wing base.
 


Ovipositor: The egg-laying apparatus of insects, typically composed of two sets of valves or a tubular extension of the abdomen.

A pair of  cerci (singular, cercus) are the pair of (upper) superior appendages.

pair of  cerci (superior appendages)

 

a)

b)

c)

 

 

 

When the male curls his abdomen downand forward to grasp the female,the cerci curl under the upper rim ofthe head (in typical dragonflies) or contact the mesostigmalplates (in damselflies). Male cerci are often relatively large ap-pendages with hooks or spines for grasping.

 

The cerci (the pair of superior appendages) of females are typically simple, cone-shaped or leaflike structures and only occasionally of use in field identification.

 

Stylus of the odonate endophytic ovipositor: a mechanosensory organ controlling egg positioning


Size of a matured female Gynacantha basiguttata (Selys, 1882)

Wing span = 108mm
Body length = 71mm
Hind wing = 52mm

Female has longer wingspan then male by 10mm


This is a natural-dead spacemen of female Gynacantha basiguttata (Selys, 1882) who flew into my house in the evening attracted by light and found dead the next morning.

Gynacantha basiguttata is common in forested swamps. Flies at dawn and dusk. Hangs from low vegetation by day. Easily attracted to light.

I saw a female Blue-eyed  Darner  of the same family in http://www.wildutah.us/h_d_darner_blueeyed_female.html with similar appendages but without a pair of claw as above Gynacantha basiguttata

I read about eggs of this dragonfly family  in http://www.tombon.com/E2Aeshnidae.htm. "The female of Aeshnidae lays eggs in the plant organization (endo-phytic oviposition) or the inside of the mud (sitting-oviposition into mud or mosses)" 

This explain why this female's segment 9 and 10 are muddy with even a mud ball stuck on the pair of claw in segment 10.

This is widespread species in Asia.

Gynacantha basiguttata (Selys, 1882) 綠眼晏蜓


A male Gynacantha basiguttata is generally recognized by its swollen spherical base to the abdomen with a pair of rounded ear-like auricles on segment 2 followed by an extremely thin narrow segment 3. At the end of abdomen is a pair of long thin superior appendages.

A male Gynacantha basiguttata’s accessory organ underside of second abdominal segment.

Notice the pair of sharp hooks with dark tip (A)
And the pair of rounded ear-like auricles (B)

The pair of superior appendage is expanded into a distinct spoon shape with a concentrated tuft of hairs at its tip.

The inferior appendage is less than half the length of the superiors.


This big green dragonfly has two big green compound eyes touch in the midline and covering the head top.

This pair of eyes and the pair below are those of 2 different female Gynacantha basiguttata taken in different date.

The color of this pair of eyes easily mistaken as another species, but this pair of dark green eye is also belong to the same species of Gynacantha basiguttata, except that it was dead after 12 hours.

Previous night this female came to my house attracted by light. It was found death the next morning.

The crystal light fad when a dragonfly death, like the radiant smile fad when we rest in peace.

Gynacantha basiguttata (Selys, 1882) abdomen is long and thin with yellow rings.

Segment 1 and 2 expanded like a ball.

The small section immediately connecting segment 1 is blue color.
 

Long time ago people believed that dragonflies were able to "sew up" a persons lips.

This may be the reason why some dragonflies are called "darners"; a "darner" is also a kind of knitting needle.


 

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