Size at maturity of Liocarcinus depurator (Brachyura : Portunidae): a reproductive and morphometric study

Sexual maturity in brachyurans is often associated with an allometric chang e in the relative growth of the animal. Maturity of Liocarcinus depurator w as examined by analysing the monthly percentages of mature females (determi ned by the stage of gonad maturation and the presence of brood and sperm pl ugs) by size-class and the relative growth of different body parts: length and width of the carapace, length, height and width of the cheliped propodu s; width of the abdominal segments in females and length of the first pleop od in males. Using the reproductive criteria the size at the onset of sexua l maturity (carapace width at which 50% females are mature) in females of L . depurator is around 30-34mm cephalothorax width. Principal component anal ysis (PCA) showed chat the main source of morphometric variation for both s exes was due to heterochelia and allometric changes in growth. Morphometric variables were fitted using different regression techniques to one and two -phase growth models. The length of the first pleopod and the propodus of t he right cheliped in males, and width of abdominal segments in females show ed two clearly differentiated phases. Estimated maturity size (carapace wid th) corresponding to 50% mature animals was greater in males than in female s. In males, size at the onset of maturity ranged between 31.4 and 35.7 mm, depending on the methods and variables used. The size at the onset of matu rity in females ranged between 25.5 and 31.5 mm. In the Ria de Arousa, the size at maturity in females of L. depurator estimated using reproductive cr iteria is considerably greater than the size found based on morphometric cr iteria. The size at maturity based on morphometric criteria is greater in m ales than in females.