Acanthascus (Acanthascus) alani profundus Koltun, 1967

Tabachnick, K. R., Menshenina, L. L. & Ehrlich, H., 2023, Rossellidae (Porifera: Hexactinellida) from the Bering Sea and off Bering Island, Invertebrate Zoology 20 (1), pp. 57-89 : 62-64

Acanthascus (Acanthascus) alani profundus Koltun, 1967 .

Figs 3 , 4 ; Suppl. Tab. 2.

SYNONYMY. Acanthascus alani profundum Koltun, 1967: 93 .

MATERIAL. IORAS 5 /2/3830, 3831: RV ‘ Akademik M.A. Lavrentyev’ – 75, ROV ‘ Comanche’, sta. 9, spec. 2-3 and 2-4 correspondingly, 55.4282° N 167.2772° E, 986 m. IORAS 5 /2/3835: RV ‘ Akademik M.A. Lavrentyev’ – 75, ROV ‘ Comanche’, sta. 9, spec. 1, 55.4282° N 167.2772° E, 984 m.

DESCRIPTION.BODY.The specimens are saccular: IORAS 5/2/3835 — 600 mm high, diameter of the osculum is approximately 250 mm (a fragment of this specimen was sampled, it measures 180 mm high, 100 mm in maximal diameter of the osculum,

the walls are 10–15 mm in thickness); 5/2/3830 — 180 mm high, 100 mm in diameter, the walls are 8– 10 mm in thickness; 5/2/3831 — 110 mm high, 40 mm in diameter, the walls are 5 mm in thickness. The latter two specimens are attached to each other by their basal parts; their atrial cavities are not common. Prostalia lateralia are diactins which protrude at 10– 45 mm over the dermal surface.

REMARKS. Despite some notable differences in spicule sizes of dermal and atrial spicules and the presence of microdiscohexasters the newly found specimens are assigned to Acanthascus (Acanthascus) alani profundus Koltun, 1967 first of all owing to the presence of two size classes of discoctasters. Another type of spicules found in the new specimens is microdiscohexaster. Quite probably that the differences between our specimens and the original description of the subspecies is a result of that only a small fragment of a sponge was studied initially ( Koltun, 1967). All other spicules show a similar type in the variations described earlier and in newly found specimens. It is very likely that A. (Acanthascus) alani profundus should be synonymized with A. (Acanthascus) platei Schulze, 1899 , but it requires a significant revision since the largest discoctasters are dermal and the smallest are atrial (unlike A. (Acanthascus) alani profundus ). Another species with a notable difference in dermal and atrial discoctasters is A. (Acanthascus) cactus , but unlike the specimens discussed above this species has generally dermal stauractins and atrial pentactins.

DISTRIBUTION. Bering Sea, at 984–2440 m depth.

mal pentactins (their tangential rays) are 10–15 mm over the dermal surface. The hypodermal pentactins are most parathropal with spiny tangential rays.

REMARKS. Differences between the new and previousely described specimens of A. (Rhabdocalyptus) borealis ( Okada, 1932; Koltun, 1967) are given in the Suppl. Tab. 3. The most important of them: no microdiscohexasters in all investigated specimens were observed; smaller diameter of the oxyoidal microscleres; the ray of atrial hexactin may be notably smaller. Nevertheless these features are considered to be intraspecific, they are widening the species limits. Morever, the specimen described by Koltun (1967) has some additional intermediate parameters.

DISTRIBUTION. Bering Sea, Pacific side of Kuril Islands, at 440–2849 m depth.

Figures

Fig. 3. Acanthascus (Acanthascus) alani profundus, a ROV ‘Comanche’ photo of the specimen IORAS/ 5/2/3826. The arrow shows sampled fragment. Рис. 3. Acanthascus (Acanthascus) alani profundus, фотографиЯ выполненаЯ подводным роботом “Comanche” обраЗца IORAS/5/2/3826. Стрелка покаЗывает на вЗЯтый фрагмент.

Fig. 4. Acanthascus (Acanthascus) alani profundus, external shape. Scale 50 mm. A — two specimens: large — IORAS/5/2/3830: small — IORAS/5/2/3831. B-C — view from different sides IORAS/5/2/3826. Рис. 4. Acanthascus (Acanthascus) alani profundus, внеШний вид. МасШтаб 50 мм. A — два ЭкЗемплЯра: больШой — IORAS/5/2/3830; маленький — IORAS/5/2/3831. B-C — вид с раЗных сторон IORAS/5/ 2/3826.