Acanthascus (Rhabdocalyptus) mirabilis Schulze, 1899

Acanthascus (Rhabdocalyptus) mirabilis Schulze, 1899 View in CoL

Suppl. Tab. 5.

MATERIAL. IORAS 5 /2/3826: RV ‘ Akademik M.A. Lavrentyev’ – 75, ROV ‘ Comanche’, sta. 17, spec. 3, 55.4599° N 167.269° E, 2279 m GoogleMaps .

DESCRIPTION. BODY. The specimen IORAS 5 /2/3826 is a fragment of the 5–10 mm thick upper wall of the sponge. Prostalia oscularia and lateralia of large diactins protrude at 20–35 mm over the osculum margin. Prostalia of hypodermal pentactins protrude at about 10 mm over the dermal surface. The diameter of the osculum is about 80 mm in diameter (reconstructed). Hypodermal pentactins of both orthotropal and parathropal types have spiny or smooth tangential rays .

REMARKS. The new specimen agrees with the description of specimens of Rhabdocalyptus mirabilis ( Reiswig et al., 2013) except for the absence of microdiscohexasters. Both these specimens have floricoidal discoctasters that differ from those in the original description of this species ( Schulze, 1899) while they have floricoidal discoctasters. The discs of floricoidal discoctasters are assymetrically attached to the secondary ray, while in the original description they are completely symmetrical. Spicules with assymetrical features are also known in: A. (Rhabdocalyptus) unguiculatus ( Ijima, 1904) — a similar species with predomination of oxyhexasters and oxyhemihexasters over the oxyhexactins. This specimen also differs from A. (Rhabdocalyptus) gomezei ( Tabachnick et al., 2019) , a species with notable amount of dermal stauractins, and A. (Rhabdocalyptus) bidentatus — stauractins predominate in this species and secondary rays of discoctasters have 2 teeth ( Okada, 1932).

DISTRIBUTION. Off S of Alaska Peninsula, Bering Sea , 1143–2311 m depth .