The androgenic gland in malacostracan crustacean species produces and secretes androgenic gland hormone, which is responsible for male sexual differentiation, such as the induction and development of male sexual traits, and in turn the suppression of female sexual traits. Marmorkrebs, Procambarus fallax forma virginalis, which was identified as the first parthenogenetic species in decapod crustaceans, produces only female offspring. In this study, in order to reveal whether the Marmorkrebs crayfish is sensitive to androgenic gland hormone, we transplanted an androgenic gland from a related congener, P. clarkii, to P. fallax f. virginalis. In androgenic gland-implanted specimens, partial masculinization was confirmed: the masculinization of several external sexual characteristics (i.e., thickening of the first and second pleopods; formation of reverse spines on the third and fourth pereopods) was detected, whereas that of internal sexual characteristics (e.g., the formation of ovotestes and male gonoducts) was not. Our results imply that P. fallax f. virginalis still has sensitivity to the androgenic gland hormone and, at least partly, the hormone should be able to induce male characteristics, even in parthenogenetic Marmorkrebs.
Keywords: androgenic gland • masculinization • parthenogenesis • implantation • Marmorkrebs