Resumen

JAPYASSU, Hilton Ferreira  y  MACAGNAN, Cátia Regina. Fishing for prey: the evolution of a new predatory tactic among spiders (Araneae, Pholcidae). Rev. etol. [online]. 2004, vol.6, n.2, pp. 79-94. ISSN 1517-2805.

Pholcus phalangioides is a versatile predator. Besides capturing prey entangled on its sheet web, it invades heterospecific webs, where it preys upon insects, eggs and the resident spider. This spider shows still another predatory tactic: we have observed it catching cursorial prey outside its sheet web. This is possible because of the existence of gumfoot lines in the sheet webs of some pholcid spiders, a feature previously observed only among theridiids (a distant, unrelated spider family). This web feature was observed in Pholcus phalangioides, Smeringopus pallidus and Physocyclus globosus, but not in Mesabolivar cyaneotaeniatus or in another unidentified Mesabolivar species. Based on these observations we suggest that gumfoots are basal in pholcid phylogeny. Some predatory behaviours typical of theridiid spiders also occur among these gumfoot building pholcids (reel and ground-search); sticky-silk wrap attack occurs in all pholcids observed so far. We describe the predatory sequence of P. phalangioides when using gumfoot lines, and discuss possible behavioural homologies between pholcids and araneoids. We also discuss the evolutionary implications of these findings.

Palabras clave : Foraging behaviour; Web pattern; Web building; Behavioral evolution; Pholcidae; Spiders.

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