PEDUNCULAR ARMAMENT IN THE SCALPELLOMORPHA (CIRRIPEDIA) AND A NEW ABYSSAL SPECIES FROM THE EAST PACIFIC RISE

A unique pedunculate barnacle. Arcoscalpellum spinum, new species, was discovered on the East Pacific Rise (18 degrees S) during the 1993 '' Naudur'' cruise of the French submersible Nautile. We propose Vertebro scalpellum, new subgenus, to include this and a related species, A. br evecarinatum (Hoek), from the south Atlantic. Although basically 8 pla tes comprise each whorl of the peduncular armament in scalpellomorphs, the number in derived forms is subject to variation. The number of ve rtical tiers of peduncular plates generally relates to the number of c apitular plates and/or the sutures between them. One trend is toward t he multiplication of plates. the other a reduction. The latter is mani fest in Vertebroscalpellum by the separation of 5-plated whorls into a n imbricating 2/3 plated pattern that is unique among scalpellomorphs.