Copulatory process in Oxychilus (Drouetia) atlanticus (Morelet and Drouet,1857) (Pulmonata : Zonitidae)

Oxychilus (Drouetia) atlanticus (Pulmonata: Zonitidae) is an endemic hermap hroditic species from Sao Miguel island (Azores). The copulatory process is a mutually simultaneous event and takes about 24 h from the beginning of p enetration until the disconnection of the partners. Copulation is character ized by the progressive and complete evertion of the penis and penial caecu m. The latter, everting completely inside the bursa copulatrix, is fundamen tal to the release of the anterior portion of the spermatophore, which is t he first to be transferred. The anterior portion of the spermatophore is ho ok-shaped, aiding its anchorage to the bursa, and the posterior portion end s in a hood with an aperture through which the spermatozoa are released.