Female genital morphology and sperm storage in the velvet spiderEresus kollari(Araneae: Eresidae)

Abstract

In the present study, we examined the female genital system of a velvet spider (Eresus kollari Rossi 1846) using light and electron microscopy. The female entelegyne genitalia of E. kollari comprises an epigyne with an anterior wide longitudinal bar and folds which are incurvated sidewards. The anterior end of these folds corresponds to enlarged anterior bulges which are connected to a distinct copulatory duct leading to lobular spermathecae. The anterior bulge is equipped with many large pores whereas the spermathecae has many small pores. At present, only a few studies have focussed on the ultrastructure and possible function of adjacent epithelia in entelegyne genitalia of spiders revealing the presence of complex class 3 gland cell units around the spermathecae and ducts. Alternatively our analysis finds two different types of epithelia. The anterior bulge is equipped with class 3 gland cells whereas the spermathecae are surrounded by a putative transport epithelium. This epithelium is characterized by an extensive basal labyrinth, numerous mitochondria, and an invaginated cell apex with microvilli. The functions of the different parts are unclear, but the secretion produced by the class 3 cell glands in the anterior bulge could be involved in the transport of sperm by flushing a considerable quantity of secretion towards the posterior. Alternatively, it could also contribute to the amorphous mass which is formed during mating covering most of the epigyne. On the other hand, the epithelium around the spermathecae might only be involved in the alteration of the milieu in the spermathecal lumen but not contribute to the nutrition of spermatozoa during sperm storage.