First autochthonous records of Balanus perforatus Bruguière (Cirripedia balanomorpha) and Conchoderma auritum (L.) (Cirripedia lepadomorpha) in the coastal waters of the Netherlands

On 4 September 1976 and on 15 December 1976 respectively, two buoys were washed ashore on the Frisian island of Terschelling, both near the village of Oosterend. They were found by mr. G. Doeksen, who collected some operculate barnacles and one stalked barnacle from these buoys. Part of the collected material he put at my disposal. Besides specimens of Balanus balanoides (Linnaeus, 1767), Balanus improvisus Darwin, 1854 and Elminius modestus Darwin, 1854 — all common in Dutch coastal waters — there appeared to be attached to the first buoy two specimens of the barnacle Balanus perforatus Bruguière, 1879 (pl. ι), and to the second buoy four specimens of the same barnacle. Because the buoys were numbered, their exact location could be traced by consulting the Pilotage service of Terschelling. Fig. 1 shows the approximate location of the buoys. Table 1 shows their geographical location. Once attention was drawn to the occurrence of the barnacles, a member of the crew of the patrolvessel of the Pilotage service — mr. A. de Jong — collected another 11 specimens from buoys, which were all located near the buoys which had been washed ashore (see fig. 1 and table 1). All the barnacles were collected alive; two of them were lost. On the buoy washed ashore on 4 September 1976 also a stalked barnacle was found. This specimen proved to be Conchoderma auritum (Linnaeus, 1767) (fig. 2). The location of these buoys being not very far off the Dutch coast — about 15 km — these records are the first autochthonous records of B. perforatus and C. auritum from the coastal waters of the Netherlands. Balanus perforatus has been recorded many times before from our coast, and specimens are preserved in the collections of the Rijksmuseum van Na-