Water spider | Thalassius albocinctus

Thalassius albocinctus (Doleschall, 1859) (Family: Pisauridae)

Common name: Water spider

Size: Female 15-20 mm, Male 10-14 mm

Distribution: India, Myanmar, Philippines

Description: Cephalothorax longer than wide, anterior end abruptly narrowed at ocular region. Cephalic region is slightly elevated in the middle. Dorsum clothed with minute pubescence. Mid-dorsal area blackish brown with lateral sides bordered by white lateral stripes, a bluntly triangular yellowish patch below ocular region. Fovea longitudinal and long. Ocular region hairy. Eyes eight, both rows recurved, anterior row shorter and strongly recurved, posterior row longer. ALE smallest, almost half the size of AME. Eyes dark brown and encircled by black bases, PLE on black lateral tubercles, black bases of PLE extending slightly towards inside and touching the ALE. Ocular quadrangle square like, minutely wider at anterior end. Long black hairs present behind posterior eyes, AME and PME nearly equal in size. Clypeus broad, height more than two and a half times the diameter of AME. Chelicerae reddish brown, hairy, provided with boss, more than twice longer than wide with anterior end narrower. Promargin with three teeth, apical tooth smaller, middle larger, basal slightly smaller than middle. Retromargin with three equal sized large teeth. Labium and maxillae similar in colour with chelicera but more lighter. Labium truncated at apex with a constriction at the base, anterior margin more yellowish, basal one-third darker, scopulate at apex. Maxillae longer than broad, apical region bears scopulae. Sternum longer than broad, yellowish brown and hairy. Legs yellowish brown, long and clothed with hairs and spines. Tarsus three clawed, two superior claws bear nine teeth each, inferior claw with two teeth. Leg formula 4213. Pedipalp similar in colour with legs, tarsal claws with four teeth. Abdomen longer than wide, narrower posteriorly, basal half broader with anterior end truncated. Pedicel visible from above. Dorsal surface black with white lateral longitudinal stripes, median black patch has a small inward notch in the posterior half. Dorsum flat, uniformly covered with fine pubescence. In young specimens, dorsum is provided with seven pairs of small white dots, only the anterior four pairs are visible in adults. Six pairs of sigilla present, posterior pair are less conspicuous. Ventrum with a broad triangular dark brown band, bordered by yellowish patches on lateral sides. Epigynum with posterior end of lateral lobes converging, anterior end diverging, anterior and posterior margin provided with dark brown hairs between lateral lobes. Resting on the top of leaves with its four legs of each side placed together in two sets.

Natural History: Live in the vegetation attached to swamps and other water bodies and sometimes feed on the water surface of small insects.

Contributed By : Sudhikumar A.V.