oa Annals of the Natal Museum - On the morphology, anatomy, histology and function of the tarsal organ on the pedipalpi of Palystes castaneus (Sparassidae, Araneida)

Volume 21, Issue 3
  • ISSN : 0304-0798



Available literature is reviewed. The morphology and anatomy of the tarsal organs of Palystes castaneus are fully descriptionbed. The course taken by the bulbus and embolus in expansion of the genital bulb is descriptionbed step by step. Histological investigations of the tarsal organs of P. castaneus yielded the following hitherto unreported data: (i) The proximal and median portions of the receptaculum seminis are surrounded by two kinds of glands, namely the vesicular and syncytial glands respectively; (ii) blood vessels going to the above glandular tissue of the bulbus via the umbilical tissue (new terminology) of the retractor ligament; (iii) the absence of connections between the bulbus lacuna and the glands in the spongy tissue of the bulbus, the bulbus lacuna thus being a vascular 'cul-de-sac'; (iv) an organized arrangement of non-elastic and elastic chitinous fibres in the basal hematodocha which is responsible for the swivelling motion of the bulbus in a definite direction; (v) each spermatozoon is encapsulated. Sperm induction is probably achieved by capillary force or resorption of secretions in the lumen of the receptaculum seminis or even more possibly a combination of both factors. The mechanism operating ejaculation of sperm in P. castaneus is shown to be probably by the secretion of a colloidal substance from the vesicular glands into the fundus of the receptaculum seminis via small pores in its walls. The force pushing this secretory mass is probably the combination of hydrostatic pressure toge­ther with release of turgor pressure from the glands supplying this secretion. Stimulation of the glands is brought about by an endocrine factor probably released by a neurosecretory mechanism.

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