A new Discorhabdella (Porifera, Demospongiae) a new Tethyan relict of pre-Messinian biota?

Abstract

A new sponge species is described from specimens found at a depth of 534–604 m off the Mediterranean side of the Gibraltar Strait (Alboran Sea). This species is closer to the New Zealand type species, Discorhabdella incrustans Dendy, than to the other known species of the genus from the Azores, D. tuberosocapitata (Topsent). It differs, however, from the former by the size of the tuberculated tylostyles, the presence of an apical tooth on the echinating acanthostyles, teeth number and size of the anchorate chelae and the presence of sigmas.

Furthermore, the characteristic echinating acanthostyles of this new species closely resemble those found in Oligocene deposits from New Zealand. The similarity between the new species and the fossil pre-Messinian Indo-Pacific species, along with the strong differences from the Atlantic species, suggest a Tethyan affinity for this new species.