Taxonomic status and phylogenetic relationship of some Algerian shallow-water sea cucumber species (Holothuroidea: Echinodermata) deduced from mitochondrial DNA sequences

Abstract

The present study focuses on the taxonomic revision and phylogeny of some shallow-water Algerian sea cucumber species belonging to the genus Holothuria [the two morphotypes (A & B) of Holothuria (Holothuria) tubulosa (Gmelin, 1791); Holothuria (Roweothuria) poli (Delle Chiaje, 1824) and Holothuria (Roweothuria) arguinensis (Koehler et Vaney, 1906)]. The nucleotide sequences of the 16S rRNA gene obtained by [1] were used to construct the phylogenetic tree of the studied specimens. Our results showed that the two morphotypes (A & B) of Holothuria (H.) tubulosa are genetically separated. We also reported a close genetic relationship between the two morphotypes of Holothuria (H.) tubulosa (A & B) and Holothuria (R.) arguinensis. Holothuria (R.) poli is the most divergent species and is in a paraphyletic position with the other studied specimens. Sequence analyses of the 16S rRNA gene revealed the presence of 58 polymorphic sites: 79.25% of these sites are parsimoniously informative and 20.75% are singletons. The means of haplotype diversity (Hd) and nucleotide diversity (π) were very high.