Reproductive biology of the crab Halicarcinus planatus (Brachyura, Hymenosomatidae) in sub-Antarctic waters

Halicarcinus planatus is the only member of the family Hymenosomatidae that occurs in the southern tip of South America. The aim of this study is to determine both the reproductive cycle and reproductive traits of the population of H. planatus nearest to southern limit of its geographical distribution. Results of this work allow us to determine two consecutive reproductive periods in this species. Maximum values of gonadosomatic index, oocyte diameter and ovarian development in March and August indicate that spawning takes place in May and September. The simultaneous ovarian maturity and the embryonic development show that female H. planatus can re-mature its ovary. The capability of H. planatus to develop their ovaries while females are ovigerous is a unique feature among the sub-Antarctic decapods and probably an adaptative advantage to extreme environments. Based on the different biological features and recent environmental changes along the Western Antarctic Peninsula, our hypothesis is that H. planatus possesses the potential to invade shallow waters and intertidal zones in this region.