Macromidia genialis shanensis (Fraser, 1927)

Last May, during a field trip in the foothills of Mount Ba Vi, I bumped into a cordulid dragonfly tucked away deep in the bushes. After some shots, I caught it for closer examination of caudal appendages, and identified a male Macromidia. I first thought it was M. rapida, a species I had seen along the same stream, but I noticed some obvious differences: cerci black (pale yellowish and black-tipped in rapida), face largely dark green, large yellow spot dorsally on S6. 

Later, with the help of some documents (Fraser, Asahina), I confidently identified it as Macromidia genialis shanensis.

Macromidia species are crepuscular in nature and rest in dense vegetation near streams during day. They become active as rain threatens or dusk approaches, circling and zigzagging low over streams.

Head metallic dark green, except yellow labium and yellow anteclypeus.

Synthorax marked on sides with 2 broad, green metallic stripes, enclosing a citron-yellow area; beneath (lower part of metepimeron) also citron-yellow. 
Wings hyaline tinged with yellow at the base. 
Abdomen black, with S7-9 inflated; S2 with a dorsal spot; S3-5 with a middorsal yellow longitudinal line; S6 with a large oval-shaped dorsal spot. 

Anal appendages wholly black, of nearly the same shape as in M. rapida.

Tip of abdomen, dorsal

Male basal abdomen with secondary genitalia, lateral (M. rapida on the right for comparison). Note the shape of genital lobe: triangular in M. g. shanensis and rounded in rapida 

               Male head (right, M. rapida)

                      Male abdomen, dorsal (right, M. rapida)

The genus Macromidia is purely oriental in distribution and contains a dozen of species, among them 2 has been recorded in Vietnam: M. genialis and M. rapida.

A number of subspecies of M. genialis have been described. Macromidia g. genialis is known from Peninsular Malaysia, M. g. erratica from Java, Sumatra and Sarawak, M. g. shanensis from Myanmar, Thailand, Laos, Vietnam (+China?).

The first record of M. g. shanensis in Vietnam is recent (in 2011, by Karube). Its inconspicuous nature may at least in part account for the paucity of records. 

I found this male at a partially shaded, 3 meters wide rocky stream with well vegetated banks, but running through an open, heavily logged forest at the foothills of Mount Ba Vi. This suggests that this species do not require high quality habitats and therefore should be more common.

Megalestes distans Needham, 1930

 

A stunning Megalestes with the majority of thorax coloured bright metallic green, which is pruinosed with oily whitish deposits in mature males.

Male, without flash - more natural appearance I think.

Male, with flash - sharpness and contrast increase.

  
Abdomen of male dull reddish (blackish at intersegmental sutures) except S1-2 green metallic on dorsum and S8-10 dark brown.

Dorsal synthorax and mesepimeron metallic green (with orangey highlights when the light is right!) with humeral (mesopleural) suture black. Metepimeron and metepisternum pruinosed white, except a short horizontal dark green stripe (which does not reach the spiracle) on the latter.

 

Prothorax blackish with central lobes with metallic green reflections. Posterior lobe pale yellowish.

Dorsal view

Anal appendages blackish brown ; superiors slightly longer than S10, forcipate with basally, on the inner side, a short quadrate process. Inferior appendages much shorter, with two pairs of curved spines in lateral view.

 

Lateral view

I encountered the female on 2 occasions. The photos below of an ovipositing female were taken in September along a forested stream (< 1 m wide), at the first slopes of Tam Dao so at a very low altitude (ca 200m).

 

  

She is very similar to male and also brightly coloured with metallic green but white pruinosity on sides of synthorax is replaced by yellow and the abdomen is duller.

Megalestes distans is known from China (Guangdong, Guangxi, Guizhou, Henan, Hubei, Hunan, Shaanxi, Shandong, Sichuan, Yunnan, Zhejiang) and several localities in northern Vietnam.

I mostly encountered the males in August (the wettest month here in northern Vietnam), at montane and submontane well shaded streams – but one time as low as 200m a.s.l. (ovipositing female).

The closest congener of Megalestes distans is M. haui Wilson & Reels, 2003 (described from Guangxi), which has similar overall colouration and similarly shaped superior appendages. The two species can not be confidently separate without study of penile organ. 

At Ba Vi and Tam Dao, only M. distans has been recorded. In Vietnam, M. haui is known, at least, from Sa Pa (Lao Cai Province) (Dô Manh Cuong, pers. comm.).

Habitat, Ba Vi (800m a.s.l.). Small swift-flowing, rocky stream (2-3m wide) with heavy covert. Males Megalestes distans were perched low at the banks.
Other  Zygoptera species spotted there (in August): Anisopleura qingyuanensis, Cryptophaea vietnamensis, Noguchiphaea yoshikoae, Coeliccia acco, C. onoi, C. scutellum, Atrocalopteryx coomani, Protosticta satoi, Devadatta ducatrix, Agriomorpha fusca, Drepanosticta sp.

Earlier in the season (May, June), remarkable Anisoptera species were recorded there, such as Merogomphus tamdaoensis, Chlorogomphus auratus and Sinorogomphus nasutus satoi.

Protosticta satoi (Asahina, 1997)

Asahina (1997) described the subspecies Protosticta khaosoidaoensis satoi based on some differences of color pattern of thorax and abdomen compared to the nominotypical subspecies from Thailand.

Later, van Tol (2008) raised this subspecies to species rank, and described two forms of P. satoi, a normal form and a dark form. He then stated it was possible that the dark form of Protosticta beaumonti Wilson, 1997 figured by Wilson and Reels (2003) from Guangxi may be conspecific with the dark form of this taxon, and the normal form may be conspecific with prototypical beaumonti from Guangdong. If so, P. satoi is a junior synonym of P. beaumonti. This taxonomic issue is not yet clarified.

This slender and delicate Platystictid damselfly live low in the dense forest undergrowth, making very short hunting flights. It is a tame fellow which likes to pose for the pictures. Often its curiosity will bring it close to you. Many times I saw it hovering just in front of my nose!

Labium whitish. Pronotum with anterior and posterior lobes blackish, median lobe whitish.

Dorsal synthorax dark-greenish with metallic sheen. Sides with pale brown mesepimeron, dirty yellow metepisternum and metepimeron with a fine stripe over metapleural  suture.

Abdomen long and thin, but S8-9 obviously inflated. Pale blue marking on S9 in both sexes.  

The shot above is the best I could do with showing the appendages (rubbish, I know). Superior appendages strongly curved with complicated protuberances. With a macro lens, impossible to get detailed close-ups of so tiny parts of the body.

Female.

 Female is similar to the male in general maculation pattern, but abdomen more stout.

 

Female.

P. satoi dark form can immediately be distinguished by its almost wholly black synthorax with a triangular posterior marking on the metepimeron.

The coloration of the pronotum of the males shows significant variation, the median lobe may be either fully pale colored or heavily smudged dark.

P. satoi is only known from northern Vietnam. It is not an uncommon sight in lowland and montane forest streams at Tam Dao, Cuc Phuong, Ba Vi National Parks... Sometimes, I found it along streams in heavily degraded forest, but always with dense marginal vegetation. The dark form is rarer.
Further studies should reveal whether P. satoi is a junior synonym of P. beaumonti, or whether both represent distinct species.
More information about genus Protosticta in Vietnam here.