Anatomical and Histological Structures of Male Reproductive System in Long-Horned Beetle Isotomus speciosus (Schneider, 1787) (Coleoptera: Cerambycidae): Light and Scanning Electron Microscopic Study

Abstract

Isotomus speciosus is a polyphagous insect that damages coniferous and deciduous trees. There is no study on the male reproductive system of I. speciosus although it is an important pest. For this purpose, the male reproductive system anatomy and histology of I. speciosus were investigated using light and scanning electron microscopy. According to the results obtained, the male reproductive system of I. speciosus consists of a pair of testes (each with a pair of separate testis lobes), two pairs of vasa efferentia, a pair of vasa deferentia, an ejaculatory duct, an aedeagus, and three pairs of accessory glands. Each testis lobe has about 65 testis follicles. Testis lobe has sperm development stages (growth, maturation, and differentiation). Each testis lobe is connected to the vas deferens via the vas efferens. There are masses of mature sperm that completely fill lumen of the vas deferens. The vas efferens has cylindrical epithelium, and the vas deferens has cubic epithelium. The vas deferens then opens into the aedeagus by an ejaculatory duct. The ejaculatory duct has an intima layer with spines, monolayer of epithelium, and muscle layer. In this study, similarities and differences in anatomy and histology of male reproductive organs of I. speciosus with other coleopteran species were revealed.