Pycnogonida from the Bellingshausen and Amundsen seas: taxonomy and biodiversity

Abstract

The Bellingshausen and Amundsen Seas are among the least studied Antarctic areas. Pycnogonids constitute a common and conspicuous component of the Antarctic marine fauna. Antarctic pycnogonids have been widely studied and are usually more abundant than elsewhere. Therefore, they represent a key taxon to understand the zoogeographic and bathymetric distributions of the fauna from these two poorly sampled seas. Furthermore, we aim to compare the diversity and composition of the pycnogonids in these areas with those in other Antarctic zones. Three main surveys were carried out in these regions (Bentart 2003 and 2006 and Biopearl II 2008). In total, 879 pycnogonids belonging to 65 species were recorded in 49 stations. Two new species are described: Heteronymphon krappi n.sp. and Nymphon nakamurai n.sp. Ammothea magniceps and A. hesperidensis are recorded for the second time in the Antarctic. The most abundant family is the Nymphonidae (60.5 %), and Nymphon australe is the most abundant species (25.5 %). The biogeographic analysis revealed 39 species in the Bellingshausen Sea (16 new records) and 19 species in the Amundsen Sea (18 new records). The circumpolar pattern is the most common found. The Bellingshausen Sea seems to be a poor area in terms of abundance and species richness compared to the Amundsen Sea and other Antarctic zones. Faunal similarity was clustered into three main groups: the shallow-water stations, the outer continental shelf stations and the slope stations. The abundance of individuals likely responds to the varying amount of organic matter that reaches each bathymetric zone.