Etude morpho-géométrique de l’espèce Stramonita haemastoma (Linnaeus, 1767) (Gastropoda : Prosobranchia) par la technique des points homologues au niveau de la côte de Mostaganem.

Abstract

The species Stramonita haemastoma is a Gastropod belonging to the family Muricidae, very common on the rocky coasts of the Mediterranean. In Algeria, very few studies have been devoted to this species. Therefore, a morpho-geometric study based on the homologous points of S. haemastoma (Linnaeus, 1767) was carried out on the coast of Mostaganem. A sampling of 165 individuals was carried out at seven stations (Stidia, Salamandre, Sidi Medjdoub, Hadjedj, Ain Brahim, Sidi Abdelkader and Ouled Boughalem) from the mediolittoral floor. The stations have been classified into four groups; each one corresponds to a region grouping together the closest stations [the Stidia group, the Mostaganem group (Salamandre and Sidi Medjdoub), the Sidi Lakhdar group (Hadjedj and Ain Brahim) and the group of Achaacha (Sidi Abdelkader and Ouled Boughalem)]. The shells of all individuals were photographed in front view and measured by considering the length (L), the width (R), the distance between the apex and the anterior canal (ACa) and the distance between the anterior canal and the posterior canal (CaCp). The ratios R/L, ACa/L, CaCp/L and R/CaCp were calculated with the aim of carrying out a Principal Component Analysis (PCA). In order to carry out the morpho-geometric study, a Canonical Analysis of Variances (CVA) was carried out by considering 19 landmarcks chosen on the photographed shells. The results of the PCA and the CVA showed that the groups of individuals representing the study regions are more or less separated from each other. The morphometric dissimilarity of S. haemastoma individuals between each group could be caused by allopatric speciation due to geographic isolation.