Intra-follicular visceral musculature in Omorgus freyi (HAAF) (Coleoptera : Trogidae) testes

The testicular follicles of the desert-adapted beetle Omorgus freyi (HaaF) (Coleoptera: Trogidae) are unusually large, relative to male size. The adva nce of the sperm-producing cells towards the efferent duct and, eventually, that of spermatozoa to the deferent duct, is apparently facilitated by the unique structure of these extended follicles. In contrast to the typical i nsect follicle, those of O. freyi and other scarabaeoid beetles have an int ernalized and elongated efferent duct. But, additionally, in O.freyi, the f ollicles are subdivided by longitudinal septa, radiating from the central e fferent duct. A net of slow-supercontracting visceral muscles extends throu ghout the septa and efferent duct. We hypothesize that this unique structur e is an adaptation maximizing reproductive potential by mobilizing large nu mbers of spermatozoa throughout the huge testes and transferring them to th e female during the irregular short bouts of reproductive activity followin g the unpredictable rainfall. (C) 1999 Elsevier Science Ltd. All rights res erved.