Named by Carter.
Original description: Large cruciform test with massive deep lacuna and a short central spine on each ray tip. Rays wide, subrectangular in axial section, upper and lower surfaces planiform. Rays slightly expanded towards tips; tips rounded, not tapering. Pore frames surrounding and within central lacuna large, mostly triangular in shape with moderately large nodes at vertices; pore frames smaller towards ray tips. Lacuna occupying most the central area of test. Primary spines at ray tips short and rod-like.
Original remarks: Crucella cavata giganticava n. ssp. differs from C. cavata cavata in having much larger, more regularly shaped pore frames with stronger nodes at vertices, and primary spines are smaller. Lacuna in C. cavata giganticava n. ssp. larger than in all other subspecies.
Etymology: From Latin: giganteus, -a, -um giant, gigantic and cavus, -a, -um caved; adjective.