Genus : Rhyothemis

The genus Rhyothemis includes five species with short abdomens and broad hind wings. Both wings frequently have extensive areas of solid color. They perch in sunlight and are found most commonly in open country. Some species are notable for the way they twist their wings obliquely relative to the sun. This behavior is believed to aid in thermoregulation. They also often rest with the fore and hind wings held at widely different angles, typically with the forewings raised and the hind wings depressed.

Rhyothemis triangularis is a small species. Solid color on the wings is limited to deep, metallic-blue basal patches. It inhabits the edges of lakes and drains from the lowlands. Males often hover over the breeding site and are swift in flight. Unlike some other members of the genus they are rarely found together in large numbers and seldom stray far from the water. It is only moderately common in Borneo but widespread in Asia. Image left is a female Rhyothemis triangularis.

Rhyothemis phyllis is a common species in Sabah. It  is recognizable by the distinctive brown and yellow bars at base of the hind wing. It is widely distributed in lowland areas and is generally to be found around drains and lakes. While hawking it has a fairly slow, sailing flight but at the breeding ground males perch for long periods over the water. It is the largest member of the genus in Borneo. Various races are widely distributed in the Oriental and Australian regions.

Rhyothemis obsolescens is a smaller species (S hw, 21.5-23 mm) with both wings almost entirely metallic-bronze. It is locally abundant in open marshes and blackwater drains in low country, particularly at the edges of peat swamp forest. Sometimes it swarms on ridges up to 800 m.

Rhyothemis pygmaea is distinctly smaller and has broader wings, but otherwise is rather similar to R, obsolescens. It occurs in much the same situations, but is quite uncommon.

Rhyothemis aterrima is a larger species ( hw, 29-30 mm) with wings entirely metallic blue-black in color shot with a bluish- or greenish-gold iridescence which sparkles in sunlight. It is found locally on lakes and in blackwater marshes in lowland areas and where present may be abundant. Males are very aggressive and frequently engage in high speed pursuits, buffeting one another with an audible clash of wings. Many specimens show much wear and tear from these hostilities.

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INDEX OF DRAGONFLY