N. fluctuans is distributed widely in SE Asia; in the plains and hills it is one of the most common dragonflies of the swamp, pond and slow running stream habitats. The brown wing markings in the male are one of the distinctive features of this species. The brown area in the forewing extends from wing base to close to pterostigma, whereas in the hindwing, at the costal side it reaches almost the same level as in the forewing, but at the margin it bends towards the wing base (Fig. la). In immature stage the spots are pale yellowish, becoming gradually darker with maturity (Fig. 1 b). In the female, the wing colouration is variable; from almost colourless to such resembling the male (cf, F. RIS, 1911, Colins zool. Selys Longchamps 13: 566-569; S. ASAHINA, 1985, Cho-cho 8[9]: 31- -33). On May 2, 2001,1 have captured an aberrantly coloured male at Pondok Tanjong, Perak, in peninsular Malaysia. Its forewing is similar to a typical male, but the hindwing colouration is much different. Only 2 or 3 costal cells are patchy brown, the remaining area of the standard spot being pale yellow. The colouration is symmetrical in both wings (Fig. 2), Judged from the darkness of the forewing spot, the individual appears rather mature. The other parts of its body,