Benthic hydroids (Cnidaria, Hydrozoa) from the continental shelf and slope off Queen Mary Coast (East Antarctica)

Abstract

Hydrozoans are one of the main, and more characteristic, zoological groups in Antarctic benthic communities, yet there are still vast Antarctic areas where the hydrozoan fauna is scarcely known, or even completely unknown, particularly in East Antarctica. The main goal of this study is to contribute to fill that gap of knowledge by studying the benthic hydroids present in the material collected at depths between 404 and 1,156 m off Queen Mary Coast (East Antarctica) during an Australian Antarctic expedition in 2009–2010. A total of 44 species, including Acryptolaria frigida sp. nov. and Halisiphonia prolifica sp. nov., has been found, belonging to the orders Anthoathecata and Leptothecata. The hydrozoan fauna of the studied area is composed of typical representatives of the Antarctic benthic hydroid fauna, with a good representation of some of the most characteristic Antarctic genera, such as Oswaldella and Staurotheca, but with scant representation of others, such as Schizotricha. The dominant species in terms of relative abundance are Symplectoscyphus glacialis with nine records (60 %), Abietinella operculata and Halecium antarcticum with seven records (47 %) and Acryptolaria frigida sp. nov. and Staurotheca nonscripta with six (40 %). A few species were found at a single station, being particularly remarkable the typical Antarctic genus Oswaldella, represented by three species, each present at a single station. Twenty-six species (65 %) are endemic to the Antarctic Region, 22 of them having a circum-Antarctic distribution and four being endemic to East Antarctica. Most of the species studied (93 %) are restricted to Antarctic or Antarctic/sub-Antarctic waters in their distribution.