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Records of Intersexuality in the Burrowing Crayfish, Parastacus Pugnax (Poeppig, 1835) (Decapoda, Parastacidae) with Comments on the Sexuality of the Species of Parastacus

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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 pugnax 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 1 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 Parastacus. En base al análisis de los caracteres sexuales de 538 especímenes de Parastacus pugnax, capturados en una población ubicada en el límite sur de su rango geográfico, Rudolph (1997) caracterizó el sistema sexual de esta especie como gonocorismo con intersexualidad permanente. En esta contribución se examinan por primera vez los caracteres sexuales de Parastacus pugnax en seis poblaciones del centro sur de Chile, en un esfuerzo por verificar si esta intersexualidad también ocurre en ellas. No se encontraron diferencias en la genitalia de Parastacus pugnax entre las poblaciones en estudio, excepto en dos de ellas en las que se encontró un individuo con ovotestis. En todos los especímenes (N = 235) se observó la ocurrencia de gonoporos de macho y de hembra. Sin embargo, al comparar la morfología de los gonoporos de uno y otro sexo entre si, se distinguieron dos morfos intersexuados. Los especímenes del morfo 1 (N = 186; 79,1%; rango de tallas 14,7-55,7 mm LCT) presentan gonoporos de hembra de aspecto semi-elipsoidal, muy calcificados, sellados, y en aquellos de mayores tallas papilas fálicas prominentes con gonoporos de machos abiertos al exterior. En cambio, los especímenes del morfo 2 (N = 49; 20,9%; rango de tallas 23,4-54,1 mm LCT) tienen gonoporos de hembra elipsoidales, no calcificados o parcialmente calcificados, con una abertura próxima a su borde interno, papilas fálicas poco prominentes con gonoporos de macho cerrados. Las disecciones permitieron comprobar la presencia simultánea de oviductos y espermiductos, los que en 233 especímenes (99,1%) conectaban una gónada única — ovario o testículo — a los respectivos gonoporos. En los otros dos (0,9%), los gonoductos se conectaban a un ovotestis. Estas disecciones junto con los análisis histológicos de las gónadas permitieron distinguir tres tipos de intersexos: con testículo (machos), con ovario (hembras) y con ovotestis. En los ovotestis no se encontraron evidencias de tejido ovárico o testicular en degeneración. También se comprobó que todos los especímenes del morfo 2, son hembras intersexo cuyos abdómenes poseen pleuras más altas que aquellas existentes en el abdomen de los machos intersexo. Las evidencias reunidas ratifican la intersexualidad permanente de Parastacus pugnax. Sin embargo, el hallazgo de dos especímenes con ovotestis hace necesario nuevos estudios que examinen muestras más grandes, tomadas durante un año en estas u otras poblaciones, en las que también se deberían analizar los parámetros medioambientales. Finalmente, comentamos el estado actual de conocimiento de la sexualidad de las especies de Parastacus.

Affiliations: 1: Departamento de Ciencias Básicas, Universidad de Los Lagos, Casilla 933, Osorno, Chile; 2: Departamento de Ciencias Básicas, Universidad de Los Lagos, Casilla 933, Osorno, Chile;, Email:


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