Rhinagrion hainanense Wilson & Reels, 2001

Male, Xuân Son National Park

Wilson and Reels (2001) described Rhinagrion hainanense from a single male collected from Lumu, Hainan, in June 1999. Rhinagrion yokoii Sasamoto, 2003 is a junior synonym of this species (Kalkman and Villanueva, 2011).

All the photos of this post were taken mid-October 2013 at Xuân Son National Park (Phu Tho Prov., northern Vietnam).

The males of the genus Rhinagrion are among the most striking and colourful damselflies. In the field they are easily recognized by having a colourful abdomen with red, blue, orange or pink markings and wings that are hyaline and open at rest.

They perch quite low above the ground and make short flights on the edge of, or within, dense shrubby vegetation along streams.

 Male

Some features of the male Rhinagrion hainanense  : 

Head black with extensive blue-green pattern.
Antehumeral stripe roughly parallel sided, covering about two-thirds length of synthorax. 

Side of synthorax with dark stripe along metapleural suture not connected to dark dorsum of synthorax. 

Male in hand, for better view

Male, facial pattern

Abdomen largely brown-reddish, S3–7 with pale band on posterior half of each segment, S8–10 black with pairs of blue dots on S9–10, superior appendages pale. Sternum of S7–10 brick-red.

Male, tip of abdomen, lateral and dorsal views

During the courtship, this male was hovering in front of the female and arched his abdomen to display the bright brick-red color on ventrum of S7-10 (abdomen was bent downwards at right angles so more bent than the left shot show). The crappy photo in the right show quite well how the tip of abdomen was spread out. And it was not only spread out, it also quivered like a tiny flag!

Female is much less colorful than the male. She show a pale version of the male color pattern, with an apricot ground color. Antehumeral stripe blue-green.

Female

Same, close-up

A male and 2 females at an oviposition spot (muddy banks of a pond)

Ovipositing female 

In his blog thaiodonata, Dennis Farrell photographed a female ovipositing at the base of a log overhanging a stream (see here)

Rhinagrion hainanense is currently known from China (Hainan, Guizhou Prov.), Thailand, Laos (as R. yokoii from Sekong in southeastern Laos), northern and central Vietnam [Xuân Son National Park (Phu Tho Prov.), Cuc Phuong NP (Ninh Binh Prov.), Chu Yang Sin NP (Dak Lak Prov.), Phong Nha-Ke Bang NP (Quang Binh Prov.), Phong Dien Nature Reserve (Thua Thien Huê Prov.), Khanh Hoa Prov.].
The locality at Chu Yang Sin National Park in Vietnam was given as a “sandy forest stream” and that at Phong Dien Nature Reserve as “2m wide and 20 cm deep through disturbed forest”. In Hainan the species is found in dense vegetation beside shady, slow-flowing streams in lowland areas (Kalkman and Villanueva, 2011).
The locality at  Xuân Son National Park - where these photos were taken - is a 30m x 5m pond with clean water, 1 m deep, at the edge of an undisturbed lowland forest.

In August 2013, I also bumped into a male at Tây Thiên (lower slopes of Tam Dao NP), at a tiny pond in degraded secondary forest.

Ten species of Rhinagrion are known. Four are known from continental southeast Asia (hainanense, mima, viridatum, macrocephalum) and the remaining six species from Indonesia, Philippines and North Borneo (Sabah) :

-Rhinagrion borneense Selys, 1886 Brunei, Malaysia (Sarawak, Sabah), Indonesia (Kalimantan)
-Rhinagrion elopurae McLachlan in Selys, 1886 Malaysia (Sabah)
-Rhinagrion hainanense Wilson & Reels, 2001 [syn: Rhinagrion yokoii Sasamoto, 2003] China (Guizhou, Hainan), Laos, Vietnam, Thailand
-Rhinagrion macrocephalum Selys, 1862 Peninsular Malaysia, Indonesia (Sumatra)
-Rhinagrion mima Karsch, 1891 Burma, Indonesia (Sumatra), Thailand, Vietnam
-Rhinagrion reinhardi Kalkman and Villanueva, 2011 Philippines
-Rhinagrion philippinum Selys, 1882 Philippines
-Rhinagrion schneideri Kalkman and Villanueva, 2011 Philippines
-Rhinagrion tricolor Krüger, 1898 Indonesia (Java)
-Rhinagrion viridatum Fraser, 1938 [removed from synonymy of R. mima] Burma, Peninsular Malaysia, Thailand 

Note that R. mima has also been recorded in Vietnam, at Phu Quoc Island (extreme south-west of the country).

Agriomorpha fusca May, 1933

Agriomorpha fusca is one of the damselflies I encountered the most in the good forests around Hanoi. When the forest seems desperately empty, when nothing is flying around, there are always some valiant Agriomorpha fusca hanging around. 

May (1933) described Agriomorpha fusca from 'Fan-Chi-Schan', Guangdong. Agriomorpha is a monotypic genus.

Both sexes are quite identical in color pattern, except the face: labrum, clypeus and front of frons creamy orange in the male, yellowish in the female. There is also a slightly difference in the synthoracic pattern: the male has a wholly mat black synthorax, the female bears a short white stripe along the humeral suture, at the base of the forewing – sometimes present in the male, but less obvious. Another difference I noticed concern the protorax: sides are much paler in the female. 

According to Wilson & Reels (2001), there are geographic variations in the synthoracic pattern of this species. The Hong Kong form is the darkest with a synthorax almost completely black. The Hainan form is the most patterned with elaborate striped synthorax. 
The synthoracic pattern of the north Guangdong form, where the type was described, is intermediate between the Hainan and Hong Kong forms. There are no structural differences between these geographic forms.

At Ba Vi and Tam Dao I encountered individual with a synthorax almost completely black; but at Mâu Son, 200km further north, close to the Chinese border, specimens show a well striped synthorax - see photos below. 

A male.

A male from Tam Dao, close-up. The name “fusca” fits like a glove.

For comparison, a male from Mâu Son (Lag Son Province), near China

Close-up of another male from Tam Dao, but without flash this time. I have to use a higher ISO than I would like. A noisier, less contrasted picture, but more natural I think. In thick, dark forest, if you are not using flash, you can not reduce the aperture diameter (=increase the f-number) so the depth of field (DOF) is shallow. For me, it is important to have the entire insect sharp, so a large DOF is necessary. Actually I have only a ”scientific”/informative approach to Odonata photography - i.e. as much as possible fine details must be visible, in particular critical features necessary for proper specific identification -, maybe later I will approach my subjects from a more artsy perspective! But I am afraid I am not skilled at all in this kind of approach!

A shot showing the orange labrum, clypeus and front of frons of the male. Note also the short whitish stripe along the humeral suture, at the base of the forewing, not always present in the male, but well marked in the female.

  The male has forceps-like cerci and rudimentary paraprocts.

A female.

A female, close-up.

A bad shot of a not fully mature female - note the brownish synthorax.

I bumped a few times into pairs in copula. But it's one thing to see a mating pair, quite another to get good shots, especially in dark forest. Patience, luck and highly cooperative subjects are the most important factors to succeed.

Odonata have secondary sex organs, meaning they don't store sperm near the copulatory organ. The male must transfer some sperm from a gonopore on his 9th abdominal segment to his penis, which is located under his 2nd abdominal segment. Once he's charged his seminal vesicle with sperm, he's ready to go!

 Now let’s go for the acrobatics! The female's genital opening is near the tip of her abdomen, while the male's penis is closer to his thorax. The female must bend her abdomen forward to bring her genitalia into contact with his penis.

The famous 'wheel' formation during mating, unique to the order Odonata. 

Always a popular subject for photographing.

The female was observed ovipositing on moss growing on stream bank rock surfaces. The male perched nearby guarding his mate while she deposits eggs. 

 

Agriomorpha fusca is known from southern China and northern Vietnam. It is common and widespread throughout Hong Kong and Guangdong, and recorded from several sites in Hainan, Fujian.

I can safely say that northern Vietnam supports thriving populations of this species.