Night Octopus

Callistoctopus ornatus (Gould, 1852)

DIAGNOSIS.—Animal medium-sized to large (to 104 mm ML). Mantle round, bulbular to elongate-tubular (MWI 27–83); neck distinct to indistinct; head narrow (HWI 31–57); eyes moderate in size, slightly protruding. Funnel organ W-shaped, outer limbs slightly shorter than inner ones. Arms long, stout (ALI 80–87), tapering to slender tips, arm order I > II > III > IV. Sucker size moderate to large (Sin 5–14, females; 7.9–15, males); especially enlarged suckers absent in males. Right arm III of males hectocotylized, shorter than fellow (FAI 59–82); ligula small (LLI 2.3–6.9), elongate, with strongly inrolled margins completely covering longitudinal groove; calamus large in large specimens (CLI 13–39). Web shallow (WDI 8–14); web formula variable, sector B typically deepest, sector E shallowest. Gill lamellae 12–14. Penis long, with diverticulum as long or longer. Radula with exceptionally tall rachidian with A7 seriation. Upper mandible with long, well-marked notch along cutting edge; lower mandible with sharp, medial ridge on lateral lamellae, ridge bifurcates posteriorly. Surfaces of mantle, head, and arms with scattered, prominent, flat papillae; some papillae over eyes larger but do not form distinct supraocular cirri. Color in preservation (ethanol) reddish to reddish brown dorsally. Mantle and head with pale to bright buff stripes and spots, about 2 rows of spots extending along arms I and II, all often with raised ridge.

ORIGINAL DESCRIPTION.—Gould, 1852:476, figs. 590, 590a, as Octopus ornatus.

TYPE LOCALITIES.—Holotype: Central North Pacific Ocean, Sandwich Islands (= Hawaiian Islands).

Neotype: Central North Pacific Ocean, Hawaiian Islands, Oahu, Black Point.

TYPE.—Neotype: USNM 730020, male, 88 mm ML, in alcohol, good condition.

DISTRIBUTION.—Hawaii; Marshall Islands; other localities could represent misidentifications.

Callistoctopus arakawai Taki, 1964

DIAGNOSIS.—See “Discussion.”

ORIGINAL DESCRIPTION.—Taki, 1964:292, figs. 34–41, pls. 2, 3.

TYPE LOCALITY.—Western North Pacific Ocean, Japan, Oita Prefecture, Minami-Amabe County, near Kamae Town.

TYPE.—Holotype: Not deposited, male, 105 mm ML, 762 mm TL (presumed to be in private collection, see “Introduction”).