Cuticular spinning structures reveal evolutionary relationships in araneomorph spiders.

The present paper reviews the results from the study of spigots, i.e. cuticular spinning structures obtained by the scanning of 52 genera belonging to 28 families of araneomorph spiders. The finding of eight morphologically different forms of these structures being attached to ducts of the pyriform type of silk glands is of fundamental importance for the final conclusions. The comparative observations enable me to create a hypothesis dealing with the existence of several evolutionary lines of spiders, each of which is represented with their own form of spigots. Nevertheless the character of these spigots undoubtedly reflects phylogenetic relationships between the spider taxa. The detection of a special mechanoreceptive field on top of the anterolateral spinnerets increases the knowledge of the functional morphology of the spider's spinning apparatus.