Male Reproductive System Of Panorpidae And Panorpodidae (Mecoptera)

Most insects multiply their population through amphigenesis. The organs of reproductivesystem plays an important role in amphigenesis, it generates gametes and transfers them intothe genital chamber of females. However, previous studies mail focused on the morphology ofmale external genitalia, researches on histology and morphology of internal reproductivesystem are considerably limited.Mecoptera is one of the most primitive orders in holometabolous insects; it acts as animportant link between the Hemimetabola and Holometabola, and plays a significant role inphylogenetic study of insects. Panorpidae is the most speciose family in Mecoptera.Nevertheless, the knowledge of male reproductive system of Panorpidae is far from sufficient.We used light and electron microscopy to study the anatomy, histology and ultrastructure ofmale reproductive system of scorpionflies, based on which we described the ejaculationmechanism. On the basis of the variation of male reproductive system and abdominalsegments, we discussed the evolution of male reproductive system, and also we gave outseveral new characters used for taxonomy. The main results are as follow:In general, the male reproductive system of Panorpidae and Panorpodidae consists of apair of testes, the paired epididymis located between testes and the seminal vesicle, a pair ofvasa deferentia and the ejaculatory sac located in the genital segment.The biggest difference between Panorpidae and Panorpodidae is that the epididymis andtestes in Panorpidae are independent completely, and they were covered by transparentmembrane. The vasa deferentia between testes and epididymis are long, and the pairedepididymis attached to the seminal vesical closely. There are no accessory glands in genitalsegment. In Panorpidae, however, the testes and epididymis form a complex and were whollycovered by a layer of membrane. The vasa deferentia between testes and epididymis areextremely short. Accessory glands appear in genital segment generally. The morphology ofother organs between these two orders is similar.We studied the histology of external genital of scorpionflies. The epithelium of vasadeferentia in scorpionflies is single-layered. The intima, occupies most volume of the lumen,is well-developed and zipper-like. Based on the histology of ejaculatory sac, a small anterior part and a main posterior partcan be distinguished. The epithelium of the anterior part is simple, several protuberancesappear in the lumen, intima on ventral side is well-developed. The anterior part of ejaculatorysac is only for sperm transfer with glandular cells absent. The posterior part of ejaculatory sacconsists of the median duct and symmetrical sac. The epithelium of the median duct and theapical region of symmetrical sac are well-developed and serve a secretory function.The epithelium of accessory glands in genital segment are composed by two single blindtubes with one head free in genital and the other head opens into the aedeagus. The epitheliumof accessory glands is single-layered, and the epithelial cell is glandular and serves a secretoryfunction.The sperm pump consists of the apical region of ejaculatory sac, a piston and the pumpspace in aedeagus. The sperm is transferred into the female genital chamber under thecombined action of ejaculatory sac and piston.We compared the male reproductive system between Panorpidae and Panorpodidae.According to the variation of male reproductive system, characters following could be usedfor taxonomy of Panorpidae:(1): the variation of7-8abdominal segments;(2): the relativelocation of testes and epididymis;(3): the relative location of testes and semical vesicel;(4):the variation of ejaculatory sac;(5): the variation of accessory glands in genital segment.