Comparative Analysis of the Male Reproductive System in Bothriuridae Scorpions: Structures Associated with the Paraxial Organs and the Presence of Sperm Packages (Chelicerata, Scorpiones)

The male reproductive system of seven species of the family Bothriuridae are compared. These scorpions are Bothriurus flavidus Kraepelin, B. cordubensis Acosta, B. bonariensis (C. L. Koch), B. chacoensis Maury & Acosta, Brachistosternus ferrugineus (Thorell), Timogenes dorbignyi (Guérin-Méneville), T. elegans (Mello-Leitão) and Urophonius brachycentrus Pocock (Bothriuridae). Additional comparisons are made with the buthid Zabius fuscus (Thorell). Observations on the structures associated with the paraxial organs (testis, seminal vesicle and accessory glands) are given. Sperm obtained from the male reproductive tract and fresh spermatophores as well as from the female's genital atrium and seminal receptacles are examined. Accessory glands occur in six out of eight studied bothriurids and in the buthid Z. fuscus. In most species the distal portion of vas deferens has a developed ampulla. All structures vary in size and shape depending on species. Sperm packages were observed in all bothriurids. In contrast, there is no packaged spermatozoa in Z. fuscus. Each sperm package consists of many spermatozoa surrounded by a common membrane that breaks after the spermatophore capsule is everted into the female genital atrium, releasing the spermatozoa. One hour after insemination, the spermatozoa are found in the atrium and in the seminal receptacles of B. flavidus females, but after 24h spermatozoa are found only in the seminal receptacles. The functional significance of the accessory glands and the presence-absence of sperm packages are discussed.