Reproductive biology of the land crab Cardisoma guanhumi (Decapoda: Gecarcinidae) in north-eastern Brazil

The reproductive cycle of Cardisoma guanhumi was described from the analysis of seasonal variation of the gonadal maturation stages. The first maturity for both sexes was determined based on three different tests: inflexion point on the curve; relevant character (morphometry); and histological analysis (physiology). In addition, some aspects of sexual dimorphism for the population were studied. A total of 353 individuals caught in north-eastern Brazil between December 2006 and November 2007 were analysed. The sex-ratio was statistically equal (P ≥ 0.05) and the carapace width (CW) of the females ranged from 4.34 to 8.56 cm and of the males from 2.84 to 9.22 cm. Mature females with fully developed gonads begin to appear in the dry season (August) and ovigerous females occurred from November to February, suggesting that spawning occurs mainly during the rainy season. The CW of first sexual maturity for females ranged from 5.87 cm to 6.70 cm and males from 6.22 cm to 7.20 cm. The highest percentage of individuals caught were juveniles, indicating the need for a targeted effort to preserve the species.