Atlantic Fourhorn Octopus

Pteroctopus tetracirrhus (Chiaie, 1830)

Octopus tetracirrhus Chiaie, 1830, pl. 72 [According to Robson (1929), the plate was not published with the text. Adam (1952) could not find it nor could I. The plate was, however, reissued in 1841 as plate 4.]; 1841a:4, pl. 4; 1841b:65.—Orbigny, 1840:36, pl. 22; 1845:175—Philippi, 1844: 202.—Gray, 1849:11.—Verany, 1851:25, pl. 7, 7bis—Adams and Adams, 1853:20.

Scaeurgus titanotus Troschel, 1857:51, pl. 4: figs. 4, 5.—Tryon, 1879:127.

Octopus tetracirrus.—Tryon, 1879:119, pl. 27: fig. 17.

Scaeurgus tetracirrhus.—Tiberi, 1880:42—Hoyle, 1886:14.—Joubin, 1900:36.

Scaeurgus tetracirrus.—Carus, 1890:461.—Jatta, 1896:230, pl. 5: fig. 2, pl. 25: figs. 2–13.—Lo Bianco, 1903:170, pl. 8: fig. 20.—Naef, 1916:17; 1921:538.—Grimpe, 1922:40; 1925:93.

Octopus (“Scaeurgus”) tetracirrus.—Naef, 1923:710, figs. 421a, 422–424.

DIAGNOSIS.—Animals of medium size (males 35–120 mm ML, females 35–130 mm ML). Mantle broadly oval (MWI 61.4–80.5), broadest in young specimens. Neck faintly constricted. Head narrower than mantle (HWI 44.4–64.1); eyes large, bulging. Mantle aperture narrow (A–B, after Robson, 1929). Funnel small to medium-sized (FLI 27.5–41.5), broad at base; funnel organ VV-shaped, lateral limbs slightly shorter than median limbs. Arms subequal, moderately long, stout, especially in small specimens, distinctly longer in adults and longer in females than in males (ALI males 66.5–82.1, females 70.2–86.5; MAI males 22.3–27.1, females 19.2–21.5). Suckers deeply set in arms, small; enlarged suckers absent in both sexes (SIn males 3.0–6.6, females 2.8–4.3). Left arm III of male hectocotylized (HALI 40–66), shorter and stouter than opposite arm (OAI 57–75), bearing 70–80 suckers. Ligula broadly conical, with blunt tip (LLI 2.3–2.9) and deep groove, transverse ridges faint; calamus well developed (CLI 25–40), pointed. Web moderate in depth (WDI 20.2–25.6); web formula A > B > C > D > E; sector E distinctly shallower than sectors A–D. Web membranes not continued over outer edge of each arm but fused on dorsal side; muscular cord extended from their point of union along median line of arms. Ink sac present, well developed, more or less embedded in digestive gland. Gills with 9 to 10 lamellae per outer demibranch. Mature ova 7 mm long, 2.5 mm wide, stalks varying in length from 2.0 to 4.5 mm. Male organs in mature specimens very large. Penis moderately long (PLI 13.8–32.7), with distinct, large diverticulum. Spermatophores long (SpLI 79.8–95.5). Radula with A2 or A3 seriation of rachidian. Skin loose, subcutaneous tissue soft and gelatinous. Two distinct slender papillae over each eye. Dorsal mantle, head, and arm bases covered with small tubercles, arranged in regular pattern. Color in life uniformly bright orange red to orange yellow.

ORIGINAL DESCRIPTION.—Chiaie, 1830, pl. 72.

TYPE LOCALITY.—Western Mediterranean Sea, Naples.

TYPE.—Not designated, not extant.

DISTRIBUTION.—Mediterranean Sea: Western and eastern basins, southern part of Adriatic Sea. Eastern Atlantic Ocean: From west coast of North Africa to just south of the equator, including the Azores and Cape Verde Islands. Western Atlantic Ocean: From United States (North Carolina) to Uruguay; in the Gulf of Mexico and the Caribbean.

This species lives on muddy bottoms on the lower part of the continental shelf and the continental slope in depths of 100–720 m (Mediterranean Sea).

deep shelf to upper slope