THE REPRODUCTIVE ANATOMY OF MALE FRESH-WATER PRAWNS MACROBRACHIUM AUSTRALIENSE (HOLTHUIS, 1890) IN SOUTHEAST QUEENSLAND

The male reproductive tract of M. australiense consists of a pair of l obulate testes which individually give rise to a single vas deferens. The vas deferens contains four distinct regions: a short proximal sect ion, a convoluted section, an elongate distal section and an enlarged terminal section. Spermatozoa produced in the testes acquire additiona l eosinophilic and basophilic matrices as they are transported along t he length of the vas deferens. The resultant sperm cords are stored in the enlarged distal vas deferens until ejaculation when the products of both vasa deferentia fuse together to form the spermatophore. The s perm are typically palaemonid, being ''thumb-tack'' shaped, with a cup shaped central nucleus which is supported by radiating fibrils. These fibrils anastomose centrally at the base of the nucleus to form a pos terior membrane bound spike.