Partial protandric hermaphroditism in the burrowing crayfish Virilastacus rucapihuelensis Rudolph and Crandall, 2005 (Decapoda, Parastacidae)

Rudolph and Crandall (2005) found a high percentage (81.3%) of intersex specimens with supernumerary gonopores in the Virilastacus rucapihuelensis type series. To determine the sexual system of this species, the sexual characters of 734 specimens collected from 5 populations of V. rucapihuelensis were examined. Six sexual forms were initially identified, on the basis of the presence or absence of gonopores in the coxae of the third and fifth pair of pereiopods. Subsequently, anatomical and histological analysis of gonads, gonoducts and androgenic gland, made it possible to distinguish three basic sexual types: male, female and intersex specimens; the latter comprise a male phase and two forms in female phase, which would originate from male phase intersexes. Ovigerous females and secondary sexual characters associated with eggs incubation were identified in adult females and in the intersexes in female phase. Evidence gathered suggests that V. rucappihuelensis is a partial protandric hermaphrodite species, with primary males and females. The possible neurohormonal mechanisms responsible for this type of sexual system are discussed, as are the external factors that could have a modifying effect on them.