Southern Ocean Asteroidea: a proposed update for the Register of Antarctic Marine Species

Abstract Background The Register of Antarctic Marine Species (RAMS, De Broyer et al. 2015) is the regional component of the World Register of Marine Species (WoRMS Editorial Board 2015) in the Southern Ocean. It has been operating for the last ten years, with a special effort devoted towards its completion after the International Polar Year (IPY) in 2007-2008, in the framework of the Census of Antarctic Marine Life (CAML, 2005 - 2010). Its objective is to offer free and open access to a complete register of all known species living in the Southern Ocean, building a workbench of the present taxonomic knowledge for that region. The Antarctic zone defined by this dynamic and community-based tool has been investigated with a particular interest. The Sub-Antarctic zone was a secondary objective during the establishment of the RAMS and is still lacking the impulse of the scientific community for some taxa. New information In the present study, more than 13,000 occurrences records of Asteroidea (Echinodermata) have been compiled within the RAMS area of interest and checked against the RAMS species list of sea stars, using WoRMS Taxon Match tool. Few mismatches (basionym mistakes : i.e. original name misspelled or incorrect) were found within the existing list and 97 unregistered species are actually occurring within the RAMS boundaries. After this update, the number of Asteroidea species was increased by around 50%, now reaching 295 accepted species.


Introduction The Register of Antarctic Marine Species, RAMS
RAMS is a collaborative and dynamic information system managing Southern Ocean marine taxon names and related information (De Broyer et al. 2015). The main objective of RAMS is to establish a benchmark of the present taxonomic knowledge of the Southern Ocean biodiversity (De Broyer et al. 2011).
In a recent appraisal of RAMS, Jossart et al. (2015) underscored the number of 10,294 described species of which 8,297 are accepted marine species (viz. checked by taxonomic experts). Among these species, 537 (~6.5%) were reported as accepted species names for echinoderms and 198 (~2.4%) as accepted names for sea star species.
After 10 years of service, RAMS still displays several spatial gaps, especially with regards to species occurring in the sub-Antarctic zone, described as the area below the sub-Tropical front (Deacon 1984, Rintoul 2007 and North of the Polar Front.
In order to complete the taxonomic information for the class Asteroidea, we propose in this work an updated version of the checklist of Southern Ocean sea stars species occurring within the RAMS area of interest.

Area of interest
As described in De Broyer and Danis (2011) the RAMS area of interest is extending from the coast of the Antarctic continent to the sub-Tropical front. Convenient operational limits have been defined (Table 1; Fig. 1), splitting the Southern Ocean into two zones: the Antarctic zone and the sub-Antarctic zone.  Table 1.
RAMS area of interest. Operational northern limits in the different sector of the Southern Ocean for both the Antarctic zone and the sub-Antarctic zone.

Figure 1.
Occurrences of RAMS (light grey dots) and Proposed-RAMS (orange dots) sea star species. The Antarctic zone is located below the green line and the Sub-Antarctic zone between the green and dark red lines. The Polar Front (black line) and the Sub-Tropical Front (dashed black line) are also shown.

Data collection
More than 13,000 occurrences records were agregated from different sources including global information systems such as the Ocean Biogeographic Information System (OBIS), the Global Biodiversity Information Facility (GBIF), initiatives such as the B iogeographic Atlas of the Southern Ocean (De Broyer et al. 2014), historic records mined from the literature pertaining to the early exploration of the Southern Ocean (e.g. Sladen 1889), recently published checklists (e.g. Gutt et al. 2014) or unpublished cruise records. Only the specimens identified at a species level, regardless of their depth (shelf, slope, deep-sea) were kept for the preparation of this checklist.
The validity of each species name was controlled using the Taxa Match Tool available in RAMS (http://www.marinespecies.org/rams/aphia.php?p=match) and WoRMS (http:// www.marinespecies.org/aphia.php?p=match) to ensure its validity and presence in the RAMS checklist.

Data resources Complete checklist of Southern Ocean Asteroidea
The data underpinning the analyses reported in this paper are deposited at GBIF, the Global Biodiversity Information Facility, http://ipt.pensoft.net/resource?r=southern_ocean_ asteroidea&v=1.1

Analysis
More than 13,000 occurrences records from 295 accepted species have been compiled within the extent of the RAMS area of interest. 198 of these species (67%) were already in the RAMS database and 97 (33%) were new to the system. After this update, the number of Asteroidea species in RAMS will be increased by around 50%.
After a careful verification of the RAMS species list for Asteroidea we propose to address the following points. These issues have been taken into account in this paper: •

Discussion
This study highlights the fact that after ten years of effort, the work is still in progress for RAMS. The main objective of covering the Antarctic zone has generally been reached for the class Asteroidea but needs at this point to go through a major update by the editors.
Regarding the asteroids, the secondary objective of covering the Sub-Antarctic zone lacked the impulse of the scientific community and we hope that the work presented here will fill the gaps as accurately as possible.
This approach may not bring the same results for all the taxa in the Southern Ocean. Indeed some charismatic fauna are very well known in the RAMS area of interest (e.g. marine mammals), however, we believe that the knowledge concerning the number of species present in the Southern Ocean waters might be significantly increased.
Only few mistakes were found in the existing RAMS list of Asteroidea and should be fixed soon after getting in contact with the editors. The new updated checklist of Asteroidea species will be available through the RAMS website (http://www.marinespecies.org/rams ) in early 2016. A way to improve the general system, with the sea stars for model is also in development.
Recent work using genetics on Odontaster species (Janosik and Halanych 2010) highlights the fact that diversity might be higher than expected even in well-studied areas. There is also a lack of ressources for identification and taxonomic work leading to redundant mistakes. In this context, the creation of a digital library, hotlinked with the RAMS and compiling original descriptions, literature materials and DNA barcoding informations for each species will bring the RAMS a step ahead and provide a vital tool for future taxonomic and biogeographic work. Perspectives also include an illustrative determination key using a polytomic approach and the creation of interactive Antarctic Field Guides (http:// afg.biodiversity.aq) on the http://www.biodiversity.aq platform  in order to help the scientific community with the identification process and to enhance data availability.
We believe that the homogenization of available data for all taxa will result in a better understanding of the Southern Ocean and its biogeography, especially in the Sub-Antarctic zone.