Family Libellulidae > Genus Oligoaeschna

Found in Asia: Brunei Darussalam, Borneo, China, Indonesia, Malaysia, Peninsular Malaysia

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.

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 observer’s eye-level.

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

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.

	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 Sarawak.
	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.

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

The 3 families of dragonflies found in Borneo Island:

1 Family of Aeshnidae

Insects are diverse and dominant inhabitants of the tropical rainforests in Borneo Island. New species are discovered too often. Entomologists are still struggling to cope with the documentation of tropical insect diversity.

Most of the common dragonflies in Sabah are red coloured, especially from the family Libellulidae. Some red pecies are even confused as same species, for example the three species of Genus Neurothemis.

Dragonflies and damselflies have large compound eyes that can see in all directions. When the compound eye is magnified several hundred times, each individual facet (ommatidium) is shown to be hexagonal in shape.

Female dragonflies have either one of the two method of depositing eggs from the abdomen:
1- using Ovipositor Structure
2- using Vulvar Lamina

Male do not have an ovipositor. Instead male dragonfly and damselfly have appendages.

GO FURTHER

FLORA

Fig trees of Sabah

Borneo has 150 species of wild fig trees. Most of them are found in forests of Sabah.

FISHERIES

Tiger Prawn Farms in Tawau

Prawn farming is a main commercial activities in Tawau. Spawners from Tawau are graded the best in Malaysia. For decades, Tawau has been exporting high-grade tiger prawns to several countries such as Korea, Japan, Taiwan, China, Vietnam, Singapore, Egypt and Australia.

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...."