Morphology of testis, sperm, and spermatheca in two capable hybridized termite species indicates no interspecific reproductive isolation

It would not surprise that two related termite species are similar in many traits, especially those related to reproduction such as similarity in sexual organs, spermathecae, gametes, glands in genital organs and micropyles of eggs. Because similarities of them are thought to be directly linked to increase their reproductive fitness. Moreover, the key data showing successful hybridization between the two termite species under laboratory conditions and in the field. The present study was conducted on the base of morphometric analyses and histological examinations of the sperm, testes, vas deferens, accessory glands, ejaculatory duct and spermathecae of Reticulitermes flaviceps and R. chinensis . The accessory glands of male alates were found without spermatozoa in both termites. The patterns of spermatogenesis in the alate testes of both species were quite similar and the gametes (spermatogonia, spermatocytes, spermatids, and sperm) produced in a sequence of essential developmental processes. The aflagellated sperm were transferred by male numerous times in a day after few copulations. They were stored alive in spermatheca by female and used for fertilization of oocytes. The nutrition was obtained by the sperm from the secretory cells, for a living and being functional during storage in the spermathecae. The spermathecae have finger shape and their thick walls divided into 4 type cells. Anatomically spermathecae of the two termite species consisted of lumens, ductules, and few glands, in thick wall structures. While the entire examinations revealed no more differences in the sexual organs of the two different species since R. flaviceps and R. chinensis can hybridize under experimental conditions as well as in wild to produce offspring. The similarity in the structure of sexual organs of both heterospecies provides possible evidence for the successful hybridization.