Rossia pacifica diegensis is a subspecies of bobtail squid native to the eastern Pacific Ocean off Santa Catalina Basin, California.

It occurs at greater depths than its sister taxon R. p.

[1] R. p. diegensis grows to 30 mm (1+1⁄6 inches) in mantle length.

Relative to its mantle size, it possesses larger fins and arm suckers, the latter being predominantly arranged in two rows.

[1] The type specimen was collected off California and is deposited at the National Museum of Natural History in Washington, D.C.[3] The validity of R. p. diegensis has been questioned.