Are the males of Aristaeomorpha foliacea (Risso, 1827) containing hemispermatophores in their terminal ampulla always sexually mature?

Hemispermatophores protect the sperm mass allowing spermatozoa to survive during mating and the passage mto the thelycum of the female. The males of Aristaeomorpha foliacea are considered sexually mature if they present the hemispermatophores in the terminal ampullae. In the Mediterranean Sea mature males of Aristaeomorpha foliacea occur throughout the year. In this research, histochemical and ultrastructural analyses were applied to investigate the hemispermatophore spermatozoo during the major mating and reproductive periods. Terminal ampulla of the vas deferentia of males containing the hemispermatophore were removed immediately after* capture in the Ionian Sea in April and July and then processed for histo logical, lectin histochemistry and ultrastructural investigations. The hemispermatophores were generally packed with typical spermatozoa, but two specimens collected in April (CL = 33 mm and 39 mm, respectively) mainly contained germinal cells considered non mature spermatozoa due to both their size and lectin staining pattern. The ultrastructural investigations revealed that these "immature hemispermatophores" contained some typical spermatozoa while they were filled with atypical germinal cells, characterized by either prominent cytoplasmic myelin-like bodies or a nuclear region with a progressive concentration of chromatin. These results indicate that the presence of hemispermatophore in the terminal ampulla is not synonymous with sexual maturity in Aristaeomorpha foliacea.