Octopus mutilans Taki 1942

Octopus mutilans Taki, 1942

DIAGNOSIS.—Animal medium-sized (40–55 mm ML). Mantle narrow, ovoid, broadest near posterior of mantle (MWI 37–50); neck distinctly constricted; eyes prominent. Funnel organ W-shaped, inner limbs slightly longer than outer ones. Arms long, slender (ALI averaging ∼85), length highly variable, tapered gradually toward tips; arm formula typically IV > III > II > I. Suckers moderate in size, sexually dimorphic (SIn 9.4, males; 5.4–7.5, females); proximal 6 to 7 suckers uniserial, suckers biserial distally; maximum of 186 suckers on longest arm; especially enlarged suckers absent in males and females. Right arm III of males hectocotylized, shorter than fellow (FAI about 50); ligula small (LLI ∼3), with longitudinal groove; calamus minute, hectocotylized arm with 52–72 suckers. Web exceptionally shallow (WDI 6–7), web formula E = D = C > B > A. Gill lamellae 7 to 8. Penis long (PLI 31), penis diverticulum small. Spermatophores moderate in length (SPL 22 mm), narrow (SPW 0.6 mm); sperm mass with 40 coils. Radula with A2 seriation of rachidian, alternating between unicuspidate and tricuspidate. Surface of mantle smooth to papillate, mantle with 20–30 low, conical papillae about 3 mm tall, arms with smaller papillae; single small, conical supraocular papilla. Color in life pale dirty grey, ground color yellowish with dark brown reticulations. Row of grey spots extended along each arm, 20–30 on longest arm. Suckers greyish white centrally, brownish around periphery. Mantle becomes uniformly brownish buff without reticulations when stimulated, arms occasionally display dark bars between spots; longitudinal bars can appear along mantle. Color in preservation (formalin) dirty yellowish brown marbled with sooty, reticulated pattern dorsally; pale, ashy yellow ventrally.

ORIGINAL DESCRIPTION.—Taki, 1942:71, figs. 3, 4, 6–14.

TYPE LOCALITY.—Western North Pacific Ocean, Japan, Hiroshima Prefecture, Seto Sea off Onomichi.

TYPES.—Syntypes: Not deposited, 11 specimens (including males and females), presumed to be held in private collection.

DISTRIBUTION.—Known only from the type locality.