Zygonyx iris Selys, 1869

I spotted many times this large libellulid along swift rocky streams, including those in open and agricultural land, in lowland and montane. The adult males hawk over a limited beat over rivers, generally over a rapid or below a waterfall. But they almost never land! And when they finally perch, they do not tolerate close approach…

Getting a good shot of this species is really difficult; but one day, you will probably bump into a tame individual that will accept what all the other ones have always refused : to be approached less than 1 meter. It happened to me.

The adult male has broad dark metallic greenish-blue stripes on thorax. Abdomen black, with mid-dorsaI carina finely yellow. Tips of wings enfumed.

Close-up on wings.

Head : frons dark metallic blue

Female (photo below) resembles the male but the lateral yellow markings on abdomen (segments 1 to 3) are more extensive, and the thorax has broad yellow stripes (the immature male also).

Male and female pair over water and travel in tandem for great distances up-stream seeking suitable situations to deposit the eggs. The larvae are adapted, by a flat limpet-like abdomen, to cling to rocks.

  A female ovipositing by dipping her abdomen tip quickly into shallow water. To get some good close-ups of the female, no other solution than to capture her with a net during mating or oviposition. The rest of the time, she is invisible.

A female perched - a rare sight!

Zygonyx iris is a widely distributed species, occurring from northeast India to southern China and south to Borneo. It is a common species over much of its range.

Remarks: Another Zygonyx species occurs in Vietnam . Z. asahinai Matsuki & Saito, 1995 

This species is known from southern and eastern China (Fujian, Guangdong, Guangxi, Zhejiang) and has been recorded in very few localities in northern Vietnam (Mau Son mountain in Lang Son Prov., Tam Dao NP in Vinh Phuc Prov., at least). 

Z. asahinai resembles Z. iris in general appearance but can be readily distinguished from the latter by the following characteristics (from Matsuki & Saito, 1995) :

1. Labium entirely black in aged stage

2. Antehumeral yellow stripe very narrow and short, both infraepisterna darkened entirely

3 ♀wings yellowish orange tinted in the basal one-fourth

4. Different configuration of male accessory genitalia and caudal appendages

5. Different configuration of valvula vulvae

Tetrathemis platyptera (Selys, 1878)

Tetrathemis platyptera is a very attractive libellulid that I have spotted on a few occasions above stagnant waters, often very small forest pools.

With its emerald-green eyes, bronze-green reflection on thorax, it is a very “photogenic” dragonfly.

The adult male has stunning blue eyes and a metallic green thorax marked broadly with yellowish stripes. 

The wings are hyaline, but the hindwings are faintly tinted with yellow. According to Fraser in The Fauna of British India, including Ceylon and Burma – Odonata (1933), the depth of the colour depends partly on the age of the specimen and partly on the locality, some showing a very intense amber tint, others with no colouring at all, especially teneral specimens.

The abdomen is black, marked with spots (lateral ones from S1 to S4-S5, which decrease in size and length from segment to segment; dorsal basal spot(s) on S7; remaining segments unmarked).

Wings, male. 

 A male caught by a wolf spider.

Female (2 photos below) almost similar in markings to the male, but the abdomen spots are larger, the wings show a much richer and deeper tint of amber.

Her abdomen is also much stouter.

I saw the female briefly, mating and ovipositing immediately after.

Copula.

The female deposits her eggs on branches or leaves overhanging water, from whence the newly hatched larvae drop into their future habitat. One day, I have seen a mass of eggs deposited on a dead branch, 30 cm above the water (watch this scene of oviposition in the video below).

A female on the branch where she will soon begin to oviposit. The male is hovering in close proximity (blue spot in background) to guard the oviposition site and prevent harassment by other males.

                                                                                       Oviposition in action.

Tetrathemis platyptera is widely distributed in tropical and sub-tropical Asia, with records from India, Myanmar, Thailand, Laos, Vietnam, China, Peninsular Malaysia, Java and Sumatra (+Cambodia, Bangladesh?).

According to some authors, this is a rather local species over much of its range, but probably under-recorded.

The place were all these photos were taken : a small pond in degraded forest, at the lower slopes of Tam Dao. Other species breeding there include Coeliccia scutellum, Orolestes selysi, Polycanthagyna erythromelas, Orthetrum triangulare, O. chrysis, Zyxomma petiolatum.

Pseudagrion pruinosum (Burmeister, 1839)

During a field trip, as I was scanning a fast-flowing stream with my binoculars, in search of odonata - not birds, I spotted 15 meters away, in a pool, a wheel pair of Pseudagrion pruinosum.

After insemination the pair flew off in tandem, landed on an aquatic plant. The female plunged her abdomen below the water surface. After a while the male released his grasp and the female completely submerged herself while the male perched above on guard. My first sighting of a submerged oviposition !

The female descended 10 centimeters below the surface. I watched the scene 30-35 minutes and left. I would have liked to see the female reappear, but there were so many things to discover around...

Normally, on her reappearance, the pair should reform in tandem.

With his orange face, reddish eyes and pterostigma, greenish abdomen (except the last segments), gray and black thorax, the male is unmistakable.

Considering that odonates abandon their water-breathing gills when they emerge, how do the adults get their oxygen when they return to the depths? According to literature, a thin envelope of air clings to the body and wings which gives them a silvery appearance while they’re under water. Body movements likely force the air in and out of tracheal openings facilitating respiration.

According to Corbet in Dragonflies: Behavior and Ecology of Odonata (1999), this  behavior is almost completely restricted to damselflies (suborder Zygoptera) which all oviposit endophytically- inserting their eggs into plant material instead of just dropping them from the end of the abdomen. The duration of uninterrupted submerged oviposition is often at least 30 minutes and frequently close to an hour. Apparently the record goes to the Marsh Bluet (Enallagma ebrium), a North American species, which is known to go submerged for an incredible five hours! Descending to at least 10 centimeters is common, but some are known to go as far as a meter below the surface!
Some advantages of underwater oviposition include exemption from harassment by males looking to copulate and protecting the eggs from desiccation.

 The male in tandem with the female, just after copulation, searching an oviposition site

In damselflies (suborder Zygoptera) the male clasp the prothorax of the female. In dragonflies (suborder Anisoptera) the male clasp the female back of the head. Those appendages, like lock and key, will only fit into the same species female; that's why they have a great taxonomic value. 

The female crawling down a plant stem to get under the surface, few seconds

before the male release his grasp. 

A completely submerged oviposition. Note the silvery appearance.

Not crystal clear water, but I was a bit responsible I think ;)

Pseudagrion pruinosum has a wide distribution throughout Asia from China to Laos, Cambodia, Vietnam, Thailand, Singapore, Borneo, and throughout Peninsular Malaysia.

It can be found in upland and mountain areas, near open streams or ponds.

In the Hanoi's area, it is a quite common sight along slow-flowing portions (almost still water) of open swift streams where aquatic vegetation can develop.

Anax guttatus (Burmeister, 1839)

In April 2012, I was fortunate to witness a tandem pair of Anax guttatus with the female ovipositing into submerged vegetation. These pictures were taken with a 400 mm lens (I was searching birds...), the equivalent to a 640 mm lens with the 1.6x crop factor of my Canon. Proxi-photo with a big lens, it can work !

This common species breeds in open and sometimes very artificial habitats, and may be found hawking around the borders of these, never wandering away from water. It is a powerful flier and very challenging to catch (the reason why I have not yet photos of male caudal appendages!).

The pair was harassed by an another fellow. Hmm, jealous of others' happiness ?...

The male has green and unmarked thorax, hyaline wings with a patch of amber-yellow on hind-wing, turquoise-blue patch on dorsum of segment 2 (striking feature, even in flight).

The female differs from the male in the following particulars only : dorsum of segment 2 broken up into four quadrangular blue patches, lateral orange spots of abdomen larger, hind-wings sometimes – not always – without the amber-tinted patch.

Anax guttatus is very widely distributed from India to Japan and Australia and Pacific Ocean Islands. It's so widespread that it has several English names - Lesser Green Emperor in Australia, Blue-tailed Green Darner in India...

It can breed in newly excavated sites that have little or no marginal vegetation.  

Epophthalmia elegans (Brauer, 1865)

During a noon stroll in one of my favorite Hanoi's "patches", a small wooded area (eucalyptus + fruit trees) with some rectangle fishing ponds - so the most man-made habitat we can imagine !, I noticed a large dragonfly resting 5 meters high in a tree. I edged forward and managed to get a few photos from different angles. It turns out that it is a new species for me... Epophthalmia elegans.

Below photos "in hand" of an another male (released after the photo shoot of course) :

A stunning facial pattern!

Lateral view of caudal appendages

Dorso-lateral view

Dorsal view

Ventral view

Widely distribution throughout China, extending through Korea and Japan to southern, far eastern Russia, northern Philippines and northern (+centre?) Vietnam.
Frequents reservoirs, ponds and lakes.
A common species, resilient to anthropogenic impacts, which can breeds in disturbed and man-made habitats.