About Paracercion calamorum (Ris, 1916)
Paracercion calamorum is a medium-sized damselfly with brown-capped yellowish green eyes. The dorsum of its thorax is black, with either no antehumeral stripes or very fine azure blue antehumeral stripes, while the related species Paracercion malayanum has very broad antehumeral stripes. The lateral sides of the thorax are greenish blue, with a fine black line on the upper part of each lateral suture. In older mature males, all of these markings are obscured by bluish white pruinescence. Its wings are transparent, and the pterostigma is yellow, bordered by thick black nervures. Its abdomen is azure blue with broad black dorsal markings extending through segment 7. Segment 2 has a distinct broad dorsal spot that connects narrowly to a fine apical ring. This marking can be used to distinguish Paracercion calamorum from species in the genus Pseudagrion. Segment 10 has a narrow mid-dorsal black streak. Females have duller coloration overall. Their abdomen follows the same general pattern as the male abdomen, but the lateral ground color is greenish-yellow, and segments 8 and 9 have broad black markings on the dorsum. Segment 10 is bluish-green in females. Aged females also develop pruinosity. This damselfly breeds in stagnant, weedy ponds, and rests flat on floating grasses and lotus leaves. Females insert their eggs deep within the up-curled rim of lotus leaves or other floating vegetation.
