RECORDS OF INTERSEXUALITY IN THE BURROWING CRAYFISH, PARASTACUS PUGNAX (POEPPIG, 1835) (DECAPODA, PARASTACIDAE) WITH COMMENTS ON THE SEXUALITY OF THE SPECIES OF PARASTACUS

Based on an analysis of the sexual characters of 538 specimens of Parastacus pugnax captured in a population located on the southern limit of its geographical range, Rudolph (1997) characterized the sexual system of this species as gonochorism with permanent intersexuality. In the present contribution, the sexual characters of Parastacus puguax are examined for the first time in six populations of central-southern Chile, in an effort to verify whether this intersexuality also occurs in these populations. No differences in the Parastacus pugnax genitalia were observed between the populations studied, with the exception of two populations where one individual with an ootestis was detected. The occurrence of male and female gonopores was observed in all specimens examined (N = 235). Nevertheless, through a comparison of different types of male gonopore morphology, and another comparison of different types of female gonopore morphology, two intersex morphs were distinguished. Morph I specimens (N = 186; 79.1%; size range 14.7-55.7 mm CL) present highly calcified, sealed, semi-ellipsoidal female gonopores and, in larger specimens, prominent phallic papillae with male gonopores open to the exterior. In contrast, morph 2 specimens (N = 49; 20.9%; size range 24.3-54.1 mm CL) have non-calcified, or partially calcified ellipsoidal female gonopores, with an opening close to their internal border, and scarcely prominent phallic papillae with the male gonopores closed. Dissection enabled us to verify the simultaneous presence of oviducts and sperm ducts, which, in 233 specimens (99.1%) connected only one gonad (ovary or testis) to the respective gonopore. In the remaining two specimens (0.9%), the gonoducts were connected to an ootestis. These dissections, together with histological analyses of the gonads, enabled us to distinguish three types of intersexes: with testis (male), with ovary (female), and with ootestis. No trace of degenerating ovarian or testicular tissue was found in the ootestis. We also verified that all morph 2 specimens are intersex females, with higher abdominal pleura than those on the abdomens of the intersex males. The evidence gathered confirms the permanent intersexuality of Parastacus pugnax. Nevertheless, the discovery of two specimens with an ootestis indicates that new studies are required to examine a larger sample, taken from either the same, or other populations, over a period of one year, that should include an analysis of environmental parameters. Finally, we comment on the present state of knowledge with regard to the sexuality of the species of Pamstacus.