The Weddellian Province and the extant rays in the Southern hemisphere

FIGUEROA DANIEL E.; BELLEGGIA MAURO; BARBINI SANTIAGO; SABADÍN D. E.; MARTIN RJ

Joao Pessoa

Congreso; Sharks International Conference; 2018

AES, SBELL, SQUALUS

The life story strategies of some ray groups make them ideal candidatesfor investigate biogeographic patterns by its distribution. Possibly the mostinformative of these groups are the skates. The skates have very high species diversity; skates havean extreme non-migratory life mode and are exclusively bottom dwelling fishesat any age, beginning from eggs with fibrillar filaments for attachment to thebottom. The cosmopolitan distribution of the group is accounted for by itslarge age. Most skate species live in the shelf and upper slopeup to 1000 m of depth, which does not allow them to move across deeper marineregions. Theyare most diverse at higher latitudes and are replaced in warm temperate totropical waters by stingrays (Myliobatoidei). The late Cretaceous/EarlyTertiary Weddellian Zogeographic Province was an area of shelf habitatencompassing part of Australasia, tip of Southamerica and the Antarctic Cratonas a bridge. Theopening of the Drake Passage in the Oligocene period, enabled the cold watersof the Pacific Ocean to penetrate in the south Atlantic, causing drasticeffects on the thermophilic fauna of the Province. Perhaps here we can find anexplanation to the dispersing of the genera in the Trygonorrhinidae Family; to thedisjunctive distribution of Sympterygiaskate species, to the remarkable endemism in Australasia and Southamerica, and tothe intrusion of the Zearaja species inthe South-West Atlantic.