Species: Platyrhinoidis triseriata, the Thornback, Thornback guitarfish

Platyrhinoidis triseriata (Jordan & Gilbert, 1880)

Thornback, Thornback guitarfish

Disc broad, oval, width about equal to length; blunt round snout; rostral cartilages wide apart at base, converging rapidly; eyes small, wide apart; large spiracle behind each eye; skin uniformly covered with small granules; 4 strong spines at snout tip; 4-5 blunt spines around each eye; 3 median rows of large hooked spines on tail, the central one extending onto the disc behind the head; a small patch of spines on each shoulder and another on the disc to the side of each eye;  2 large equal sized dorsal fins, towards rear of tail; tail thick, sides vertical, with elongate oval fin.

Grey-brown to olive-brown upper surface, white ventral surface.

Size: 91 cm.

Habitat: benthic on fine sand to mud bottoms, off beaches, in sheltered muddy bays.

Depth: 0-137 m.

California to the Gulf of California.