25/05/2012

Lamelligomphus camelus (Martin, 1904)



Habitat of Lamelligomphus camelus (Hoa Binh Province) : foothill fast flowing and open rocky stream (here surrounded by bushes and rice fields, not forest). This species was abundant here.


 Male adults usually settles on rocks in mid-stream. A quite tame creature, easy to get close to. 



The caudal appendages look rather gruesome, as they are large compared to the size of the dragonfly.


Note the “camel humps” (slightly hooked forward in lateral view) on S8 and (although the picture is not very sharp) the basodorsal tooth on the superior appendages, both diagnostic features.

For comparison, look at this other male Lamelligomphus photographed at Hoa Binh Province :

  Lamelligomphus sp.

Superficially it looks like camelus, but it is not camelus : no pair of hump-like tubercles on S8 and no dorsal tooth on the superior appendages.

 Tip of abdomen, lateral.

It is impossible to clinch identification from these 2 photos above. A specimen need to be collected. 

In the the key to Chinese Lamelligomphus provided by Wilson & Xu, 2009, the shape of the male’s hamuli are important diagnostic features, among others. 

The genus Lamelligomphus is very diversified in Chinese territory with 11 species known there (Wilson & Xu, 2009). On the contrary, only two species have been recorded from Vietnam : camelus and biforceps. The male above is not biforceps also, so clearly something unrecorded in the country.

Lamelligomphus camelus is known from eastern, southern and southwest China (Fujian, Guangdong, Guangxi, Hainan), Laos and Vietnam (North and Centre, common species, Dô Manh Cuong pers. comm.).


Many thanks to Dô Manh Cuong for the ID confirmation and the informations about this species

19/05/2012

Sinictinogomphus clavatus (Fabricius, 1775)


A female found in open field, far away from water

This is the commonest gomphid in Vietnam (at least in the North), you can see it everywhere at low altitudes. It prefers lentic waters - i.e. lakes, ponds and reservoirs. The larvae can tolerate moderate to high levels of pollution in an urban environment setting.


 It is easy to identify and fairly easy to get near to as it often returns to the same stick.


Sinictinogomphus clavatus is a rather large gomphid. Both male and female have foliaceous flaps black and yellow on S8. 
Female is similar to the male in color & markings. I saw it at few occasion when ovipositing.



A male and an exuvia - which also belongs to this species.

A female - photo above (on the right) + photo below - laying eggs under male control.



Another oviposition shot (female on the right), this one taken at an artificial pond in Hanoi downtown (cemented beds, no aquatic vegetation, less than 5 species of odonata spotted). This tree stump covered with algae/mosses was one of the rare suitable place for oviposition.

Male in flight.

A teneral female (wings not yet hardened, eyes greyish).

This species has a broad range from Nepal, Myanmar, Thailand and Vietnam through to southern, southwestern and central China to Korea, Japan and southern, far eastern Russia.

17/05/2012

Aethriamanta aethra (Ris, 1912)



Visiting repeatedly this pond in the suburbs of Hanoi, invaded by water hyacinth (Eichhornia crassipes), yielded a range of common species (such as Pseudothemis zonata, Rhodothemis rufa, Crocothemis servilia, Urothemis signata, Brachythemis contaminata, Brachydiplax chalybea, Ceriagrion auranticum, Onychargia atrocyana, Anax guttatus, Sinictinogomphus clavatus, Tholymis tillarga…)
but also, surprisingly, some unexpected goodies...
As with bird-watching, a great deal can be achieved by regularly covering
a "local patch".

 Curiously, Aethriamanta aethra was absent from the odonata list of Vietnam until March 2011 when Dô Manh Cuong and Bui Huu Manh found it during a survey in the mangrove forest of U Minh Thuong National Park, province of Kien Giang, southern Vietnam.

I wrote "curiously" because 4 months after this discovery, I came across this nice species in the... Hanoi suburbs, along a pond which didn't look very healthy, surrounded by a wooded area which was, at one time, a garbage dump ! If this species can accept such ecological conditions, it should be much more common ! Well, in theory... But maybe the explanation is just : the lowland open ponds remain under-explored.

This site was also home to Aethriamantha brevipennis. I took also good close-up shots of a Gomphid (anal appendages included) which, according to Dô Manh Cuong, has never been recorded in Vietnam. Specimens will be collect next year for further study.


Mature male blue pruinosed (thorax and S1-7). I searched individuals at mid-stage but with no success. Maybe they perch higher in the treetops.




A young male, before it becomes heavily pruinosed and looks entirely blue.



Acrobatic postures under the heat of the mid-day sun.