Phylogénie et phylogéographie de quelques espèces d’holothuries aspidochirotes de la côte algérienne (Ouest et centre)

Abstract

In this study, we have revised the systematics of some aspidochirote holothurians of the Algerian coast, using a part of a database provided by Mezali (2008). The detailed study of the morphological, anatomical, molecular and endoskeletal data, allowed us to: 1) identify a few individuals of an invasive species of Atlantic origin [Holothuria (Roweothuria) arguinensis (Koehler et Vaney, 1906)], already signaled by Mezali et Thandar (2014) ; 2) separate Holothuria (Roweothuria) poli of other species ; 3) discuss the taxonomic status of Holothuria (Holothuria) stellati, extensively debated for a long time in the literature and 4) give some precision on the two morphotypes of Holothuria (Holothuria) tubulosa (A & B) previously reported by Mezali (2008). Our study was based on a thorough review of the endoskeleton (ossicles) of sea cucumbers, studied using modern morphological geometry technics and several statistics and bioinformatics methods. Holothuria (Holothuria) tubulosa B whose morphological, anatomical, endoskeletal and molecular characteristics are totally different from the classic Holothuria (H.) tubulosa (rated A) already described by Koehler (1921). The statistical methods (hierarchical clustering and canonical analysis) allowed us to validate this result. Indeed, the canonical analysis showed highly significant and distinct differences between the two morphotypes of Holothuria (H.) tubulosa (A and B). This previous result corroborates with that of the molecular analysis and confirms that those two cryptic species are well different. A phylogeographic analysis was tackled using some DNA sequences available in GenBank and Bold.