The First Report of Holothuria (Thymiosycia) impatiens (Forsskal, 1775), (Holothuroidea: Holothuriidae) from Tunisia (Mediterranean Sea): Taxonomic, Morphological, and Molecular Data Compilation

For the first time, specimens of Holothuria impatiens are reported from the Tunisian coast, supported by molecular (COI sequencing) and morphological (examination of ossicles) analyses. For comparative purposes, Holothuria impatiens samples were genetically analyzed with existing data from Spain, Italy, and the Red Sea. In addition to their external morphology, an external substance covering the individuals is described, besides the new ossicle structure described in the body wall of H. impatiens samples. The results of the morphometry of the specimens from the Tunisian coast revealed that, for two shapes of ossicles, the size of the individuals does not influence their structures. Low genetic diversity was observed in Tunisia, with two haplotypes; one of both haplotypes was reported for the first time exclusively in Tunisia. The phylogenetic tree showed that the haplotypes were shared across all locations, revealing that the Mediterranean and Red Sea individuals were clearly distinct. Further studies on the genetic diversity of H. impatiens are crucial for the evaluation of the singularity of Mediterranean populations.

Automated summary

This study reports for the first time the genetic and morphological analysis of Holothuria impatiens specimens from the Tunisian coast. The morphometry of the Tunisian specimens revealed that the size of the individuals does not influence their ossicle structures. Low genetic diversity and a unique haplotype were observed in Tunisia.