Searching for Mediterranean bath sponges (Demospongiae: Dictyoceratida: Spongiidae) in the Northeast Atlantic reveals a new species: an integrative taxonomic approach

Abstract Bath sponges, included in the Spongiidae (Demospongiae: Dictyoceratida), are distributed across the oceans of the world, with a greater abundance in temperate, subtropical, and tropical zones. Their harvest started during ancient times in the Mediterranean Sea, which shed light on the whole family. Most of the Mediterranean Spongiidae have been reported repeatedly from the Northeast Atlantic, notably along the Iberian peninsula. The aim of this study was to clarify the taxonomic status of these sponges after a recent sampling effort in the French Pays Basque and the Spanish Cantabria, complemented by several Mediterranean Sea stations, including the Strait of Gibraltar. An integrative taxonomic approach was adopted for the first time on a set of Spongiidae samples from the Northeast Atlantic, assessing the congruence of analyses of: (i) the morphology of the spongin skeleton; (ii) two different parts of the genome (mitochondrial and nuclear); and (iii) metabolomic fingerprints, to delimit the frontiers between species better. A new bath sponge species is described herein, and significant advances and changes are proposed for the systematics of the family.