Abstract
Tanais dulongii (Audouin, 1826) is a small benthic crustacean with separate sexes and a marked sexual dimorphism characterized by a cephalothorax narrowed anteriorly, larger chelae (claws) and a pair of tiny genital cones in males, and ovisacs that form chambers for carrying embryos in females. Recent studies have described the existence of intersexual individuals with a cephalothorax similar to males, large chelae and ovisacs, but, due to their small size, it has not been possible to confirm the presence of genital cones under normal light microscopy. The present study analyses and compares external reproductive structures under scanning electron microscopy, of male and female T. dulongii, to corroborate the presence of both ovisacs and genital cones in potentially intersex individuals. The possible causes, such as hermaphroditism, environmental sex determination, parasitism, genetic aberration or endocrine-disrupting pollutants, are discussed.
Acknowledgements
The authors would like to thank Lic. Mónica Oppedisano (Laboratorio de Microscopía, Universidad Nacional de Mar del Plata) for their help with the SEM. This work is part of the doctoral thesis of C.E. Rumbold and was supported by a Ph.D. fellowship from Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET: PIP 112-201101-00830) and Universidad Nacional de Mar del Plata (UNMdP: EXA 610/12). Thanks also due to Dr Louise Allcock and two anonymous referees for their comments on an earlier version of this manuscript.