Genus : Orthetrum
5 species of the old world genus Orthetrum are known from Borneo.
Sabah has 5 species of Orthetrum
All are widespread and very common. Red species may be confused with other genera such as Rhodothemis and Crocothemis but are readily separated by the fact that the distal antenodal cross vein in the forewing is complete in Orthetrum, but incomplete in the other genera . All Orthetrum have a broad hind wing with an anal loop distinctly in the form of a sock, but it must be noted this feature is not restricted to the genus.
1) Orthetrum chrysis is widespread from lowlands up to about 1000 m. It is most common in old, well vegetated drains running alongside forest but it is present in virtually every type of standing and slowly running water, and is occasionally encountered inside forests on pristine streams.
2) Orthetrum testaceum is found from the lowlands up to 1500 m, but in poorer quality habitats. The yellowish immature are common garden dragonflies, and it breeds mainly in open, even concrete drains in urban or cultivated areas. It is quite uncommon in the less disturbed habitats preferred by Orthetrum chrysis.
3) A third red species with even more fastidious habitat requirements is Orthetrum pruinosum (hw, 33-36 mm). The abdomen is a deeper red than in Orthetrum chrysis or testaceum and the thorax and basal segments of the abdomen are deep pruinose blue. The base of the hind wing has a small brown spot rather than a broad golden yellow patch. It is common on slower flowing and rapid streams in primary mixed dipterocarp forest from lowlands to 1000 m.
4) Orthetrum glaucum is overall powdery blue with a dark spot at the base of the wings. It is found in very poor habitats in open areas, especially newly made and concrete drains in cleared land. It flies from sea level to at least 1500 m.
5) The distinctively marked black and greenish-yellow Orthetrum sabina is found in similar situations but also occurs commonly in lakes and at the edges of weedy marshes. It is more inclined to wander far from the breeding site than other species; hence is often encountered in grassland far from water or at high altitude over 2000 m. It breeds at least as high as 1000 m and is one of the widest ranging of all odonate species, occurring from Australia to Africa. It is a fierce predator and often takes butterflies and smaller Odonata.
6) Sarawak has the 6th species of genus Orthetrum, the Orthetrum borneense.
Orthetrum borneense is endemic and known from only a few
specimens from the type locality at 1350-1500 m on Mount Dulit, Sarawak. It may
be a fugitive forest dweller, seldom encountered but more common than supposed.
It is most like Orthetrum glaucum but, among other differences, the wing venation is
considerably more open.