Common Name
Southern Thorny Skate
Year Described
Pozzi, 1935
Identification
Body relatively thick and heavy. Disk diamond-shaped with a concave anterior margin (more so in males). Snout fairly short. Rostral cartilage stiff. Eyes moderate. Pectoral fins angular to bluntly rounded. Pectoral skeleton does not reach snout tip, leaving a semi-translucent area adjacent to rostral cartilage. Anterior pelvic fin lobe much smaller than the posterior lobe and separated by a shallow notch. Tail is thickened, about 72% of TL, and has skin folds on both sides. There are two dorsal fins, separated from each other by a distance less than first dorsal base. The caudal fin is very small. Upper jaw with 30-38 tooth rows. Clasper very stout and broad.
Body covered with dermal denticles dorsally. Ventrum smooth. There are around 3 orbital thorns. There are 2-3 scapular thorns. There are 1-2 nuchal thorns. The abdomen and tail have a row of 12-15 thorns. Body thorns are very large, especially in young, with conspicuous stellate bases. Scattered thorns on rest of body, including malar, alar patches (male), snout, and a band on either side of tail. No interdorsal thorns.
Color
Dorsum uniformly medium to dark brown. Markings are restricted to diffuse blotches when present. A pale patch is usually present in front of the eye and the snout is semi-translucent. The ventrum is whitish with gray spots.
Size
Maximum size to 69cm TL.
Habitat
Found from 50m to over 1000m on the continental shelf and slope.
Range
Southwestern Atlantic: Uruguay to Argentina and the Falkland Islands. Also the southeast Pacific off Chile.
References
Last, P.R., White, W.T., Carvalho, M.R. de, Séret, B., Stehmann, M.F.W & Naylor, G.J.P (Eds.). 2016. Rays of the World. CSIRO Publishing, Melbourne.
Other Notes
There is a complex of similar skates in the genus Amblyraja in the Patagonian region that are difficult to separate using morphology and coloration is possibly the most useful character. The pale-bellied Amblyraja doellojuradoi and A. georgiana are partially sympatric in the Patagonian region with the latter being more common in the southern ocean. The existence of the widespread pale-bellied A. hyperborea in the South Atlantic is unclear and would complicate identification. Amblyraja frerichsi is sympatric with A. doellojuradoi but has a characteristic dark ventrum. Records of Amblyraja taaf in the SW Atlantic are misidentifications of other pale-bellied Amblyraja.