A new symbiotic scale worm (Polychaeta: Polynoidae) living in association with burrowing callianassid shrimps in the Black Sea

A new scale worm tentatively assigned to the genus Malmgrenia McIntosh, 1874 (Annelida: Polynoidae) is described from the burrows of callianassid shrimps belonging to the genus Gilvossius Manning et Felder, 1992 (Decapoda: Axiidea: Callianassidae). This is the first association involving callianassid shrimps with a polynoid scale worm, known from the Black Sea (northeastern basin) and even for the Atlantic Ocean basin. The taxonomy of the new species, as well as the previously known associations of scale worms with callianassid shrimps are also discussed.