Common Name
Thickbody Skate
Year Described
Krefft, 1968
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 small. 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 77% 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 38-48 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 18-26 thorns. Body thorns are very large, especially in young, with conspicuous stellate bases. Scattered small thorns on rest of body, including malar, alar patches (male), snout, base of pectoral fin, and bands on either side of tail. There are 0-2 thorns between the dorsal fins.
Color
Dorsum dark brown to dark gray with blackish edging on the disk. Fins blackish. Body thorns noticeably paler. Ventrum similar in color to dorsum: dark gray to brown with white around gills, cloaca, and mouth. Young fish have more extensive white patches.
Size
Maximum size to 91cm TL.
Habitat
A deepsea species found on the continental slope and abyssal plain between 600-2610m. Averages deeper than other members of the genus.
Range
Southwestern Atlantic: found off S. Brazil to the Falkland Islands and the Straits of Magellan. Also off Chile in the Pacific Ocean.
References
Bustamante, C., Lamilla J., Concha F., Ebert D.A., Bennett M.B. 2012. Morphological Characters of the Thickbody Skate Amblyraja frerichsi (Krefft 1968) (Rajiformes: Rajidae), with notes on its biology. PLoS ONE 7(6).
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.