Genus : Neurothemis

Size measurement for the 4 species of Neurothemis matured male in Sabah :

Male : N. fluctuans N. terminata N. ramburii N. disparilis
Wing span = 52mm 66mm 56mm  
Body length = 34mm 41mm 36mm  
Abdomen = 22mm 27mm 24mm  
Hind wing = 25mm 30mm 26mm  
Males of Neurothemis species are generally obvious by virtue of their extensively pigmented red-brown wings with very dense reticulation. The wings of the females most commonly are either clear and unmarked or have a very light suggestion of the male pattern.

See a comparison of the matured males of above 3 species of Neurothemis

The changing color of pterostigma
Neurothemis terminata terminata  (Ris, 1911 ) Neurothemis fluctuans
 (Fabricius, 1793) 		Neurothemis ramburii ramburii
(Kaup in Brauer, 1866)
Neurothemis's  pterostigma color tense to change on sun ray reflection.  This change of pterostigma color were observed in 2 species
The following photo was taken at 6:01 PM. 20-2-2007 under the setting sun light.

Left image of wing directly facing sun light appeared as yellow pterostigma.

Right image with tip of wing in shadow of camera blocking direct sunlight appeared as red pterostigma.

 The following photo was taken at 5:29 PM. 20-2-1007

The right pair of wing facing the sun shown yellow pterostigma

while the left pair of wing in shadow shown red pterostigma

Click on the image to enlarge the photo.

 

  
 

1) Neurothemis fluctuans

Neurothemis fluctuans  is a comparatively small species (hw, 21-25 mm) with the border of the pigmented area on the hind wing usually curving back to meet the hind margin well before the level of the pterostigma. The extent of this dark patch is variable, sometimes reaching the base of the pterostigma and sometimes extending to the distal end. The wings of the female are unmarked.

Common in open, disturbed habitats and also ventures far from its breeding site. It breeds at least up to 1000 m and may be found much higher as a vagrant.

2) Neurothemis terminata

 
Neurothemis terminata is larger ( hw, 28-32 mm). Looks similar to Neurothemis fluctuans species but is larger, and the hind wing red area is truncated abruptly near the tip of the wing, with straight margin i perpendicular to the wing margin.

The female may be marked similarly with a light yellow suffusion, occasionally deep orange in old specimens, or the wings may be uncolored except for a small dark brown mark at the tip. It is found in similar habitats to Neurothemis fluctuans, but is more prevalent in less disturbed areas.

When a male Neurothemis terminata just immerged from excuvia, the color is chocolate brown. I have not seen the emerging process of a male Neurothemis terminata but on 2 occasion early in the morning (February 2007) I spotted the teneral male Neurothemis terminata warming up a meter above the monsoon drain its came from.  It maiden flight is weak and it float like a butterfly.

It might take about a week for a teneral male Neurothemis terminata to mature its color from brown to red.

Neurothemis terminata is the most difficult to get a close up image compared with the two.  This is reason why I have very little close up of  Neurothemis terminata.

3) Neurothemis ramburii

Neurothemis ramburii is common species in Sabah. It is  another frequent inhabitant of suburban drains, similar in size to Neurothemis terminata but with wing pattern rather more like Neurothemis fluctuans. Typically there is only one cross vein in the cubital space of the hind wing (behind the median space) and females are as deeply colored as males.

4) Neurothemis disparilis

Neurothemis disparilis is rare and little known. It is distinctively marked.  It is slightly larger than Neurothemis fluctuans (hw, 23-26 mm) with areas of solid brownish-red color at the base of the wings only, terminating well before the nodus.

 

Neurothemis terminata and Neurothemis ramburii sharing the same drain.

The size of this male Neurothemis ramburii appeared 1cm smaller then the Neurothemis terminata beside him.

There are several Neurothemis ramburii  on a natural pond 100 meters away. All the same smaller size then Neurothemis terminata.

Photo : 14-6-2007 Merotai
   

NEW INDEX : Dragonfly     May 16, 2008 11:23:03 AM

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