MORPHOMETRIC DIFFERENTIATION AMONG POPULATIONS OF LEPTODIUS EXARATUS (H. MILNE EDWARDS, 1834) (BRACHYURA, XANTHIDAE) FROM THE PERSIAN GULF AND THE GULF OF OMAN

The marine environment of the Persian Gulf is characterized by extreme biophysical factors, like high salinities. This gulf is a semi-enclosed basin and is connected to the Gulf of Oman via the narrow Strait of Hormuz that may act as a barrier to gene flow between the two gulfs. Consequently, animal populations living in the Persian Gulf are hypothesized to be isolated and thus to evolve independently from neighbouring populations. We tested this hypothesis with the xanthid crab, Leptodius exaratus (H. Milne Edwards, 1834), which is one of the most common intertidal crabs occurring in the Persian Gulf and the Gulf of Oman. Four-hundred-and-fifty specimens were collected from eight sampling sites, i.e., four sites each in the Persian Gulf and the Gulf of Oman. Fifteen morphometric characters were measured. Males and females were analysed separately to avoid bias as a consequence of sexual dimorphism. Due to the lack of normal distribution in males, two different approaches were carried out in this paper. Female specimens were included in parametric analyses, while males were tested with permutational multivariate analyses of variance. In female morphometric characters, t-test analyses showed significant differences between the two sets of populations, and the discriminant analysis showed divergence between the two groups (with 83% correct groupings). In the males, the applied analyses showed a significant difference (P = 0.002) between the two gulfs. These divergences can be interpreted as a consequence of regional adaptations and a low rate of larval migration between the two gulfs.