Mortonagrion aborense (Laidlaw, 1914)

Hämäläinen (1989) transferred Agriocnemis aborense Laidlaw, 1914 to the genus Mortonagrion Fraser, 1920. He also demonstrated that Agriocnemis binocellata Fraser, 1922, Indagrion gautama Fraser, 1922 and Mortonagrion simile Ris, 1930 are all conspecific with Mortonagrion aborense.

Mortonagrion aborense is a tiny creature (length : 23-24mm), easy to overlook unless you are looking for it. But once you have found one, it is quite easy to lose touch with it in the darkness of shaded ponds because of its swift flight - swift compared to many other pond damselflies I mean. However, the blue end segments of the male help it to stand out. 

Habitat, Hanoi.

 Adult male.

I only spotted adults with yellow-green stripes. But they can also be blue-striped.

A mating pair... found with the help of binoculars !

Shots "in hand" :

Greater part of labrum black; anteclypeus, bases of mandibles and postclypeus greenish ; vertex and occiput black, the latter with rounded postocular spots.

 

Prothorax black on dorsum except the anterior lobe, which is yellow-green.

Thorax black on dorsum, marked with a yellow-green antehumeral stripe on each side; laterally also yellow-green – striped. 
Legs greyish (in fact only coxae, trochanter and femur) - looks like pruinosed. 
S2 with a pair of small oval spots on dorsum; S3-6 black, with lateral stripes nearly confluent across the dorsum at base and again approaching each other subapically on each segment (these markings, except at base, nearly obsolete on S6); S7 with a pair of basal dorsal spots only ; S8 pale bluish ventrolaterally, with a basal blue ring; S9 entirely blue save for an apical row of black spines; segment 10 blue, with its apical border and the mid-dorsal line narrowly black. 

Male, tip of abdomen, lateral.

 Anal appendages black, superiors rather longer than segment 10, curved a little downwards as seen from the side, broad and hollowed out on the inner side, the apex hooked inwards as seen from above ; inferiors considerably shorter, with 2 pairs of spines as seen from above.

Male, tip of abdomen, dorsal.

The female is similar to the male, but the markings on the abdomen are slightly different. 

 Adult female.

Like many species of damselflies (e.g. genus Agriocnemis), tenerals and sub-adults are reddish. 

Teneral male.

Teneral female. 

This is the first record of M. aborense in Vietnam*. I found it... in the suburbs of Hanoi (!), at some small, well shaded ponds hidden among a tiny (one hectare) wooded area – a birding patch in fact. I never expected to find any interesting odonata there, that’s why I never really searched. But one day I had the good idea to scan thoroughly the water surface with the binoculars...

M. aborense is widespread in Asia (from India to Thailand and Laos, and south to Borneo and Sumatra), but quite local in occurrence, found in forest streams, shady ponds and marshes. Although it can sometimes be found outside of forest, it is always in the vicinity of forest and probably depends on some forest cover for its survival.

Its presence in a small wooded patch surrounding by paddy fields and residential areas, in the suburbs of a bustling megacity, is quite amazing.

*In 2013, Tom Kompier found it also at Van Long NR, Cuc Phuong NP and Huu Liên NR. It was surprising that this species had not been recorded elsewhere in Vietnam, given the unlikely location of its discovery. Yet another species that may not be as rare as the scarceness of records suggests!