A comparative morphological study of the epiandrous apparatus in mygalomorph spiders (Araneae, Mygalomorphae)

Many adult male spiders have silk glands which are not associated with the spinnerets. They occur on the anterior margin of the genital furrow and are used during the building of the sperm web and sperm droplet induction. These epiandrous glands exit the body through ducts which lead to specialized spigots. In the taxon Mygalomorphae, the presence of epiandrous spigots is just reported for a couple of species but their morphology has not been investigated. In this paper we provide a detailed study of the ultrastructure morphology of eighteen species belonging to eight families using light and scanning electron microscopy (SEM). We describe and present images of the epiandrous spigots above the genital opening. Also, we compare the morphology of spigots between families and describe the epiandrous glands through histology.