Functional morphology of the venom apparatus of the funnel spider, Agelena gracilens (Araneae : Agelenidae) from Turkey

Abstract

The funnel-web spider, Agelena gracilens Koch C. L., 1841 is widely distributed throughout Middle Europe, Mediterranean countries, and Middle Asia. The aim of this study is to describe the functional morphology of the venom apparatus in A. gracilens using scanning electron microscopy. The organization of the venom apparatus of A. gracilens follows the general structure of the venom apparatus ofother spiders. The venom apparatus is situated anteriorly in the prosoma and it is composed of a pair of chelicerae and venom glands. Each chelicera consists of a Stout basal and a movable apical (fang) segments. The fang rests in a furrow on the basal segment and it narrows apically. There are parallel fine grooves on the surface ofthe fang. To eject the venom, a venom pore is located on the subterminal part of the fang. The venom glands of A. gracilens are of equal size and tubular. Each gland is Surrounded by a bulky muscular layer. Also, neurons innervate the surface of the venom gland by SEM.