THE WEB-SPINNING PROCESS AND WEB-STRUCTURE OF LATRODECTUS TREDECIMGUTTATUS, L. PALLIDUS AND L. REVIVENSIS

The web structure and the web spinning process of Latrodectus tredecimguttatus Rossi, Latrodectus pallidus Cambridge and Latrodectus revivensis Shulov have been investigated, particular attention being given to the structure of their catching webs.
The webs of Latrodectus represent a further development of the web-type of Archaeranea tepidariorum . The specific characters of the investigated webs concern the middle layer of their three-layer webs, where more or less regular structures appear.
In the middle layer of L. tredecimguttatus web paths of hexagonal meshes appear.
In the web of L. pallidus and L. revivensis more or less regular radially arranged catching platforms appear, connected with the distant retreat by a long bridge-web.
The lower layer of vertical threads, with viscid droplets on their far ends is spread-out in L. tredecimguttatus and consists of short threads as distinct from the concentrated bundle of high threads in the two other species.
Since L. pallidus and L. revivensis appear usually among vegetation, their restricted catching webs seem to be adaptive adjustment to the biotope.
The concentration of the catching webs brings about improvement as regards prey detection.
The differences in the web structure of L. tredecimguttatus and L. revivensis indicate that their behavioural characters are more distinct than the morphological ones. The different behavioural characters support the view that L. revivensis represents a species different from L. mactans tredecimguttatus .