Polenecia producta and its web: structure and evolution (Araneae,Uloboridae)

Summary The web of Polenecia producta is interpreted as being a modified orb web. The position of the hub directly upon a twig amongst irregularly placed branches decides the web's structure. Since the radii have to be fixed in the vicinity corresponding to the local possibilities, and since these possibilities vary very much from case to case, a great variety of web scaffoldings results. All of them are characterized by a lack of symmetry. These asymmetries, for their part, prevent the production of capture threads by circling around and fixing them obliquely to the radii as do orb weavers. P. producta adapts itself to this situation by attaching the adhesive material along the radii. Under these circumstances temporary spirals, like those of orb weavers, would be without function. The short pieces of such spirals present in the webs of P. producta are interpreted as vestiges of once functional structures. The silk deposits P. producta lays down upon the hub can, in certain respects, be compared with stabilimenta of other Uloboridae. The relatively late onset of web building in P. producta (instar II spiderlings) is related to the ontogeny of the spinning apparatus.