The Magellanic Province and its fish fauna (South America): Several provinces or one?

Aim We assessed the validity of the division of the Magellanic Province into the four provinces as proposed by Briggs & Bowen (J Biogeogr 39 12-30, 2012): Southern Chile, Tierra del Fuego, Southern Argentina and Falkland (Malvinas) Islands. We aimed to (a) present an updated list of the fishes from the region known as 'Magellanic Province', (b) analyse the specific richness of fishes in the Atlantic and Pacific sectors and their degree of endemism and (c) evaluate statistically the validity of the three Provinces proposed for the Atlantic sector. Location Southern tip of the American continent at latitudes higher than 40 degrees S in the Atlantic as well as in the Pacific Oceans. Taxon 348 South American marine fish species. Methods The list of fishes was prepared by consulting more than 140 sources, many related to observations resulting from research cruises, although two ichthyological collections and two ichthyological websites were also used. The South American species with distributions extending outside of the area corresponding to the Magellanic Province, and all cosmopolitan species, were excluded of endemism analyses. For analysing fish distributions in the Atlantic sector, the data employed are from eight research cruises carried out from 1978 to 2006 from 37 degrees to 55 degrees south. A total of 523 fishing trawls have been analysed, grouped into cell of 1 degrees x 1 degrees cells. The species composition of each cell was evaluated by multivariate analysis (non-metric multidimensional scaling, cluster and similarity analyses). Results The percentage of endemism in each sector (Atlantic 2.87% and Pacific 2.87%) is smaller than the endemism common to both sectors (9.2%). The total of endemic species in the Province is 14.94%, which is bigger than the 10% indicated as the lower limit for defining a biogeographic province suggested by Briggs (Marine Zoogeography, 1974). In addition, multivariate analyses do not show differences in the species composition, neither between Falkland (Malvinas) Islands and 'Southern Argentina' nor between the latter and Tierra del Fuego. Main conclusions The ichthyological data indicate only one biogeographic province in the region not four as previously posited.