Family: Aeshnidae
Genus: Oligoaeschna
Species: Oligoaeschna foliacea
Common Name: Leaftail

Found in Asia: Brunei Darussalam, Borneo, China, Indonesia, Malaysia, Peninsular Malaysia
Sub-Order: ANISOPTERA Super-Family: AESHNOIDEA Family: AESHNIDAE

Ovipositor of a female dragonfly Oligoaeschna foliacea

Ovipositor of a female dragonfly Oligoaeschna foliacea
 

♀60mm

2008-06-02 SRI AMAN, SARAWAK

 

Ovipositor Structure:
1- Valves with stylus
2- Stylus with sensing hairs at tip
3- Cutting Basal blades

Spiky Anal Base

Paired long Cerci (Anal appendage)

Bottom view of  the terminal segments of an adult female Oligoaeschna foliacea.

1) Lam - the basal plate of ovipositor (lamina valvarum)
2) V2 - second valves of ovipositor (valvulae 2)
3) V3 - third valves of ovipositor (valvulae 3)
4) Stylus - a pair of thin needle like stylus that serves as sensor in egg positioning;
5) Spiky Anal Base - Anal base at the last segment with sharp spike that perhaps serves as anchor to stabilize the abdomen while the ovipositor is inserting eggs into plant.

 

Identification Guide to Oligoaeschna foliacea

Oligoaeschna foliacea

Male ♂63mm

body length = 63mm
hind wing = 40mm
wingspan = 87mm


Female ♀60mm not including the paddle-shaped appendage

body length = 60mm + 6mm appendage
hind wing = 44mm
wingspan = 90mm

Oligoaeschna foliacea is a very rare species of dragonfly which inhabit wooded swampy forests .

 It is crepuscular where it rests in the forests during the day, and forages for insects during dusk and dawn. This species like to rest vertically on twigs or leaves, generally slightly above an observerís eye-level.

The male is rather rare but may appear in numbers during the breeding seasons. It can be told apart from the similar O. amata by the shape of itís anal appendages. Itís superior appendages has a leaf-like profile view and itís inferior appendage is longer than that of O.amata.

The wings are uniformly covered in amber-brown. Eyes are dark green in young individuals.

Oligoaeschna foliacea is one species of Aeshnidae that is seldom seen by the dragonfly enthusiast as not only it is rare, but also it is crepuscular黃昏的, which means it is active during dawn and dusk. During the day, it rests deep in the wooded swampy forests, normally hanging vertically on leaf or twig.

A medium size Aeshnidae species. Total body length is 60mm and longer, which is slightly smaller than the more common G.dohrni and G.subinterrupta. Striking green eyes and thorax and abdomen are black with strong green markings.

The wings are slightly tinted with pale amber. Notice it has only three cells in the discoidal triangle on both wings.

 


Male

Oligoaeschna foliacea is a heavily built dragonfly. Their thorax color range from dark reddish-brown to black and marked darkly with green

Male

The male O. foliacea wings are uniformly colored in pale amber, but females often have extensive semi-hyaline reddish-brown patches.

This species of Oligoaeschna most frequently found in swampy country and alluvial forests in the lowlands. This one I found at the bank of Lupar River (a river famous for it's crocodile)

Male

O. foliacea wings have fewer cross veins in the discoidal triangle, which is usually divided into only three cells in both wings. Whereas in most other genera it is usually divided into five or more cells.

Female's hindwing base is round.


The leaf-like anal appendages

Male O. foliacea superior appendages are moderately long and robust, flattened and expanded.

 

Oligoaeschna species are similar in their body marking and can only be separated by structure of their anal appendages. I managed to find this identification from Dr. Orrís guide book page 71


A comparison of 2 females I found just 50 meters from the location the above male found.

Female 1

Found on 2 June 2008

Female 2

Found on 3 June 2008

   
The superior appendages is leaf-shape like.

This Female appendages still intact they are long and very broadly paddle-shaped with a thin stalk.

Female appendages normally break off with mating.

When intact the female appendages are long and very broadly paddle-shaped with a thin stalk. The function of these long racquet like appendage curious structures is unknown.
Female appendages already broken off with mating

 

When intact the female appendages are long and very broadly paddle-shaped with a thin stalk. The function of these long racquet like appendage curious structures is unknown.
O. foliacea wings have fewer cross veins in the discoidal triangle, which is usually divided into only three cells in both wings. Whereas in most other genera it is usually divided into five or more cells.

Female's hind wing base is round.

While the male wings are lightly and uniformly pale amber, the females have extensive semi-hyaline reddish-brown patches.
This O. foliacea female has only 2 cells on the front wing.

Dr. Orr in his book has a remark that "...Females show a good deal of interspecific variation in wing venation, wing marking and the shape of the abdomen...."

   
   
 

Oligoaeschna foliacea most frequently found in swampy alluvial forests in the lowlands.

The black tire background of this photo is the jetty of Sri Aman Town located at the lower Lupar River in Malaysia.

 


Oligoaeschna foliacea has a heavily built  thorax with color range from dark reddish-brown to black and marked darkly with green similar to the male.


 

Female Oligoaeschna foliacea.

Wings - the two main visual differences between wings of Male and Female are :

1) Wings color - This females have extensive semi-hyaline reddish-brown patches while a male's  wings are uniformly colored in pale amber.

2) Hindwing Base - Female's hindwing base is round while Male's are pointed.

The measurement of the female is :
- Front wing span is 9 cm
- Body length is 6 cm not including the appendage.
 

This Female Oligoaeschna foliacea's  appendages still intact.

Female appendages normally break off with mating. When intact the female appendages are long and very broadly paddle-shaped with a thin stalk. The function of these long racquet like appendage curious structures is unknown.
 

Bottom view of  the terminal segments of an adult female Oligoaeschna foliacea.

1) Lam - the basal plate of ovipositor (lamina valvarum)
2) V2 - second valves of ovipositor (valvulae 2)
3) V3 - third valves of ovipositor (valvulae 3)
4) Stylus - a pair of thin needle like stylus that serves as sensor in egg positioning;
5) Spiky Anal Base - Anal base at the last segment with sharp spike that perhaps serves as anchor to stabilize the abdomen while the ovipositor is inserting eggs into plant.

 

 


 

http://www.type.kahaku.go.jp/TypeDB/typedb_pub

A New Oligoaeschna (Odonata, Aeschnidae) from Thailand


 

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