Ejaculation and spermatophore formation in Culicoides melleus (Coq.) (Diptera: Ceratopogonidae)

Abstract

This paper describes the initial stages of sperm transfer in Culicoides melleus. A description of the male and female reproductive tracts is given and an account of events during the first 2 min of coitus. In this period the male secretes a spermatophore, which, during copulation, is held predominantly in the male genitalia. The course of ejaculation, involving passage of spermatozoa through the seminal vesicles and glutinous glands of the male accessory gland, and subsequently through the ejaculatory ducts, is described. Extrusion of the spermatophore at the aedeagus is illustrated and an explanation advanced to account for encapsulation of the sperm masses. The structure and content of the spermatophore is described with the aid of electron micrographs. A feature of particular interest is the "membrane complex," secreted prior to ejaculation by cells of the glutinous glands. The complex consists of a layer of membranes, which separates the ejaculate from the spermatophore walls.