Title: FACTORS AFFECTING THE DIAMETERS OF AXIAL FIBERS IN CRIBELLAR THREADS OF THE SPIDER FAMILY ULOBORIDAE
Author: Brent D. Opell
Abstract: The diameters of axial fibers that support the cribellar threads of uloborids are shown by electron microscopy to be related to web architecture. Cribellar threads produced by the simple-web species Miagrammopes animotus and M. sp. are supported by the radial threads along which they are deposited. The axial fibers of these threads have smaller diameters than those of the self-supporting cribellar threads that are deposited between radial threads by members of the orb-weaving species Hyptiotes cavatus. Among these six species, axial fiber diameter is directly related to the maximum distance that a cribellar thread spans in the web. However, in O. sinensis and H. cavatus there is no intraweb difference in the diameters of axial fibers from short and long cribellar thread spans.