Web building and prey wrapping behavior of Aglaoctenus castaneus (Araneae: Lycosidae: Sosippinae)

摘要

Funnel webs are common and widespread taxonomically, but little is known about how they are built or details of their structure. Aglaoctenus castaneus (Mello-Leitao, 1942) (Lycosidae) builds horizontal, densely meshed funnel webs of non-adhesive silk, with a tangle of lines above. Web construction behavior was unique in that the spider frequently laid swaths of lines rather than simple drag lines, both to float bands of fine lines on the breeze as bridges to distant objects and to fill in the sheet. Spiders utilized special spinneret movements to widen the swaths of lines that they laid on sheets. These movements have not been seen in web construction by other araneomorphs, but are were similar to and perhaps evolutionarily derived from those used during prey wrapping by many other species. Observations, made with a compound microscope, of the construction behavior of the agelenid Melpomene sp. O.P. Cambridge 1898, and of lines and attachments in sheets of these species and another funnel web spider, the zoropsid Tengella radiata (Kulczynski, 1909) demonstrated the possibly general nature of including obstacles in the web. This probably disadvantageous behavior may be related to constraints in selecting web sites imposed by the need for sheltered retreats, or to the spider's inability to remove preliminary lines. The observation also showed the importance of further improvements in the discriminations made between "sheet'' and "brushed'' webs in recent discussions of spider web evolution.