Psammobatis rudis

Common Name

Smallthorn Sandskate

Year Described

Günther, 1870


Disk heart-shaped with broad, rounded pectoral fins and a weakly concave anterior margin of disk (more concave in males). Snout short and soft with convex lateral edges. Conical snout tip slightly projects and sometimes has a filamentous tip. Skin with sparse denticles in juveniles but becomes smooth with age with some denticles around the margins. Ventrum quite smooth. Multiple orbital thorns in a crescent shape around each orbit. Large patch of thorns not present on shoulder and restricted to single thorns on each shoulder. There are several small nuchal thorns on midline. A weak line of median thorns runs from level of pelvic fins to dorsal fin with irregular lines of small lateral thorns. Median thorn row in a shallow groove. Tail rather slender with irregular lines of thorns. Caudal fin weakly developed. Dorsal fins are paired far back on tail, very close together, and very small. Pelvic fin with two portions separated with a deep notch. Claspers large. Mouth narrow. Nasal flaps broad with fringes. Teeth are conical and sharp (31-37 in upper jaw).


Dorsum and tail medium brown with numerous white speckles and a few random white blotches on pectoral fins. Belly white with dusky pigment on the rear margin of disk.


Maximum size to 53cm TL.


Found from coastal waters to upper continental slopes (30-475m). Benthic.


Southwestern Atlantic: Uruguay to S. Argentina. Also Chile.


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

This species has weaker thorns and a rougher body in adults than Psammobatis scobina, the only other large species of the genus with no large patches of scapular thorns.