Psammobatis extenta

Common Name

Zipper Sandskate

Year Described

Garman, 1913


Median thorns: no obvious center thorn row

Disk heart-shaped with broad, rounded pectoral fins and a concave anterior margin of disk (strongly concave in males). Snout short and soft with convex lateral edges. Conical snout tip slightly projects and sometimes has a filamentous tip. Skin of dorsum rough. Unique in having long thornlets surrounding edge of disk and covering the rear part of pelvic fin. Ventrum quite smooth. Multiple orbital thorns in a crescent shape around each orbit. Patches of scapular thorns. A few nuchal thorns on midline. Several irregular rows of thorns on midline running onto tail. Tail thick and a bit longer than disk, with several rows of thorns. Caudal fin well developed and almost as tall as second dorsal fin. Dorsal fins are paired far back on tail, close together, and very small. 0-3 thorns in between dorsal fin. Pelvic fins in two parts with a distinct notch. Claspers large. Mouth narrow. Nasal flaps broad with fringes. Teeth are conical and sharp (34-50 in upper jaw).


Dorsum medium brown with widely separated pale rosettes and spots and small black speckles. Pale bands on tail. Belly white.


Maximum size to 35cm TL.


Coastal waters from 15-160m. Benthic.


Southwestern Atlantic: S. Brazil to S. Argentina.


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 is quite small at maturity and shares that characteristic with Psammobatis rutrum and P. parvacauda. The unique marginal thornlets, tooth number, and coloration will easily separate P. extenta from the other two small species of the genus.