Acanthascus ( Rhabdocalyptus ) heteraster Okada, 1932

Acanthascus ( Rhabdocalyptus) heteraster Okada, 1932 View in CoL

Fig. 6 View Fig ; Suppl. Tab. 4.

MATERIAL. IORAS 5 /2/3824: RV ‘ Akademik M.A. Lavrentyev’ – 75, ROV ‘ Comanche’, sta. 21, spec. 4, 55°28′58.8″ N 167°15′30.6″ E, 2849 m GoogleMaps .

DESCRIPTION. BODY. The preserved specimen is tubular, about 90 mm high, 50 mm in maximal diameter; the walls are 1–3 mm thick. Prostalia lateralia are hypodermal orthotropal (rarely parathropal) spiny pentactins irregularly distributed and protruding 1–4 mm over the dermal surface.

REMARKS. The newly found specimen has spicules size parameter different from those of the type specimen described by Okada (1932) (see the Suppl. Tab. 4). The long ray of atrial hexactins (directed into the atrial cavity) in the new specimen is notably longer then those in previouse descriptions; discoctasters are of a single type and their minimal size is less than that in the type specimen and larger than the minimal size of this type of microsclere in a specimen described by Koltun (1967). The discoctasters in the new specimen are notably larger than the same type of discoctasters in the initial description, microdiscohexasters are absent and oxyoidal microscleres reach larger sizes. Nevertheless most spicule parameters of this new specimen correspond to A. ( Rhabdocalyptus) heteraster much more then to other species of the subgenus and it seem more reasonable to expand the spicule parameters in the previous species then to create a new one.

DISTRIBUTION. Bering Sea , off Pacific coast of Canada, 445–2849 m depth .