Resting Postures of Orb-weaving Uloborid Spider S (araneae, Uloboridae )

Observations of 22 orb-weaving species of the family Uloboridae show that these spiders assum e one of four basic resting postures as they hang beneath the web's hub . The primitive pattern found in Tangaroa and Octonoba is characterized by all legs being spread and about equally flexed, whereas i n Zosis the protracted first legs grasp the web at nearly the same point . Uloborus species typicall y assume a more cryptic posture characterized by acutely protracted and flexed first legs . Dense setal tufts proximal to the abruptly flexed leg segment provide outline camouflage and conceal the ex tended, shorter second legs which no longer support the body . In contrast, Philoponella species lack leg tufts and assume a compact posture with first legs folded against the sternum and only the las t three pairs of legs grasping the web. The significance of these findings for uloborid classification an d phylogeny is discussed .