Morphology of spermathecae in the estuarine crab Chasmagnathus granulata Dana 1851 (Grapsidae, Sesarminae)

The morphology of the spermathecae (seminal receptacles) was studied in the grapsid crab Chasmagnathus granulata, both from the macroscopic and the mi croscopic points of view. Female adult crabs were collected throughout the year. once in the laboratory, the right spermatheca was fixed in Bouin solu tion; histological sections were stained with haematoxilin-eosin. The obser vations indicated that the spermathecae belonged to the 'ventral type' desc ribed by Diesel (1991), related to the 'hard female" mating system of C. gr anulata described previously. They presented two distinct zones: the inner one (white-coloured), where the double layer oviduct opened ventrally; and the outer one, of translucent, 'jelly-like' appearance, where the communica tion with the genital duct could be observed. The spermatozoa were only obs erved in the 'jelly-like' zone, but not as discrete packets, suggesting tha t spermatozoa from different matings could mix in the spermathecae of C. gr anulata. The spermathecae also showed seasonal variation, with the lowest d egree of development observed during autumn. Post-moulted females always sh owed collapsed spermathecae.