Boring sponges (Porifera, Clionidae) collected during the "Tydeman" Canary Islands expedition Cancap-II, 1977

INTRODUCTION AND MATERIAL The boring sponges of the Canary Islands have never been studied in any detail, but the boring fauna of this archipelago cannot be expected to be very rich. All islands are volcanic and calcareous rocks are not common. Consequently, in most areas large shells and rhodophyte incrustations are the only substrata available for boring sponges. Moreover, the islands are truly oceanic. Eggs or larvae (according to Trégouboff, 1957, clionids are oviparous) have to cross a distance of at least 90 km to reach the Canary Islands from the African coast, where calcareous substrata are abundant. Because of the isolated position of the islands endemism may be expected. All material was obtained during the second expedition of the CANCAPproject (biological investigations of the Canarian-Capeverdian area) in August and September 1977 on board Hr. Ms. "Tydeman". Most specimens were collected by Dr. G. J. Boekschoten and Miss G. Klein Nulend during scuba-diving operations. The other specimens were recovered by dredging and grab sampling. Immediately after collecting the colour of the papillae was noted. Afterwards, the specimens were dried and in the laboratory spicules were prepared for optical microscopy. The samples are stored in the collection of the Leiden museum. List of stations. — Sta. 2-0D7: S coast of Hierro, 27°3o'N 180W, scuba-diving, depth 10 to 15 m, rocky bottom, 3 and 10 September 1977. Sta. 2-0D8 : SW coast of Hierro, 27e'42'N i8°8'W, scuba-diving, depth 5 to 2ς m, rocky bottom with some sand, 5 to 9 September 1977.