Abdopus tenebricus (E. A. Smith 1884)

Octopus tenebricus Smith, 1884

DIAGNOSIS.—Animals small (75–95 mm TL; 17–19 mm ML). Mantle elongate ovoid (MWI 60–78); head wide, slightly narrower than mantle (HWI 47–56), demarked from mantle by strong constriction; eyes very large, projecting above surface of head. Funnel large, slender, bluntly tapered (FLI 37–42); funnel organ W-shaped, limbs thin, outer limbs length of median limbs. Arms long (ALI 320–381), slender, tapering to narrow tips. Arm lengths unequal, arm order IV = III = II > I or III = II > IV > I. Suckers raised above arm surface, moderately large (SI 8–9), without sucker enlargement. Right arm III of males hectocotylized, shorter than opposite arm (HAMI 279; OAI 87); ligula narrow, small (LLI 4.4); ligula groove well marked but shallow, with very fine transverse ridges and longitudinal medial ridge; calamus moderately long, acutely pointed (CLI 24); hectocotylized arm with 93 suckers. Web shallow (WDI 14–18), web formula C > D> B > A = E. Ink sac present. Gill lamellae 7 per outer demibranch. Female specimen submature; eggs small (capsule 1.0–1.2 mm long, 0.3–0.4 mm wide). Penis long (PLI 20), with single-coiled diverticulum; spermatophores relatively short (SpLI 41–47), slender (SpWI 3.0–3.5), with large, coiled sperm reservoir (SpRI 37–43).

Integumental sculpture consists of pattern of fine, longitudinal epidermal ridges on mantle dorsum and fine, rounded, and widely set tubercles on dorsum. Ventral surface smoother. Large branched papillae present on dorsum. Papillae on mantle dorsum form approximately 3 subparallel, longitudinal rows of 3 to 4 complex, branched papillae Larger, arborescent papilla obvious in supraocular region, surrounded by 3 to 4 smaller papillae. Four rows, of 3 complex, branched papillae each, lie on surface of dorsal web and arms. Lateral integumentary ridge or fold around mantle circumference absent. Color of animals preserved in ethyl alcohol uniform dark brown dorsally, slightly paler ventrally. Ocelli absent.

ORIGINAL DESCRIPTION.—Smith, 1884:35, pl. 4: figs. B-B3.

TYPE LOCALITY.—Australia, Queensland, Bowen (as “Port Denison, Queensland”) (20°02′S, 148°15E), 3–4 fm (5–7 m), sand and rock bottom.

TYPES.—Lectotype: BMNH 1881.11.10.13–14, male, 17 mm ML.

Paralectotype: BMNH, same lot as lectotype, female, 19 mm ML.

Specimens in fair condition, preserved in ethyl alcohol.

DISTRIBUTION AND BIOLOGY.—Recorded only from type locality, in tropical waters of northeastern Australia. Biology unknown.