Octopus hattai (Sasaki 1929)

Octopus hattai (Sasaki, 1929)

DIAGNOSIS.—Animal medium-sized to large (90 mm ML, 120 mm ML). Mantle oval, relatively narrow, widest medially (MWI 50–60); neck weakly constricted; head small, about 50% of width of mantle; eyes average in size. Funnel moderately large, funnel organ W-shaped, narrow, inner limbs longer than outer ones. Arms long, distinctly unequal in length; arm formula I > II > III > IV, arms I more than twice length of arms IV. Suckers distinctly unequal in diameter, varying in accordance with arm length, those on arms I twice diameter of those on arms IV; especially enlarged suckers absent. Right arm III of males hectocotylized, slightly more than 50% of length of fellow arm; ligula small (LLI about 5), HASC 82. Web deep, web formula variable but generally A = B = C > D > E. Gill lamellae 12 to 13. Penis large, penis diverticulum recurved and folded back along penis. Spermatophores to 70 mm long and with about 50 turns of sperm mass. Radula with penti- to hexicuspid rachidian (of B2 seriation?). Surfaces of mantle, head, and basal portions of dorsal arms only with low, poorly defined papillae surrounded by faint, circular grooves connected to form network. Two to 3 large supraocular papillae in longitudinal row above each eye.

ORIGINAL DESCRIPTION.—Sasaki, 1929:87, figs. 44, 45, pi. 12: fig. 10, as Polypus hattai.

TYPE LOCALITY.—Western North Pacific Ocean, Japan, Chiba Prefecture, Kominato.

TYPES.—Syntypes: ACS, 2 males, 90 mm ML, 120 mm ML, 3 females (value of 20 mm ML given by Sasaki (1929) for 1 female syntype, but measurement must be in error as it conflicts with other data from same specimen).

DISTRIBUTION.—Known only from the type locality.