Aulocyathus atlanticus Zibrowius 1980

Aulocyathus atlanticus Zibrowius, 1980

(Figs. 2 A–A’, B, tables 1−3)

Aulocyathus atlanticus Zibrowius, 1980: 106, pl. 54, figs. A–P, pl. 55, figs. A–N.—Ramil Blanco & Fernández Pulpeiro 1990: 27.—Cairns & Chapman 2001: 34 (tab.1).—Altuna 2010: 21.

Material examined. Galicia Bank: Stn. V 6, 766 m, two specimens; Stn. V 7, 924 m, five specimens, one of them dead.

Description. Corallum solitary, attached and small (H= 1.03–1.81 cm), cylindrical or somewhat conical, occasionally slightly curved basally. Wall costate; C1–C4 subequal in width, poorly developed, extending for almost the whole wall and with small granules. Basal plate small. Calices circular (GCD= 0.47−0.68 cm); 20−42 septa in up to four cycles according to the formula S1≥S2>S3≥S4. Septa poorly exsert, descending vertically into the fossa. Axial edges straight and thickened in S1−S3, S4 thinner. Septal faces poorly ornamented, with more or less apparent granules. Fossa moderately deep, containing a circular columella formed by neat vertical rods. Corallum white to cream.

Remarks. The corallum is capable of increasing in length considerably without a meaningful increase of GCD, or even the number of septa. For instance, the longest specimen examined (H= 1.81 cm, stn. V7) has the smaller GCD (0.47 cm) and only 34 septa, with S1−S3 complete (24 septa) and up to 10 S4. Another one with H= 1.78 cm (stn. V7), has only 20 septa for GCD= 0.47 cm, with S1−S2 complete and 8S3. The highest number of septa corresponds to a GCD= 0.64 cm (42 septa). Neither specimen examined has four complete cycles (48 septa).

Specimens from stn. V6 have epizoic polychaetes, with a slight erosion of the wall. A specimen from stn. V7 (H= 1.81 cm) has also a slight corrosion. In one of the specimens of stn. V6 the worm and its corneous tube are still present. I have not verified if it belongs to Lumbrineris. An association with this worm has not been mentioned in Aulocyathus atlanticus up til now.

Aulocyathus atlanticus is a rarely recorded bathyal coral, distributed in the southern sector of the Bay of Biscay, Atlantic coast of the Iberian Peninsula, Azores, Madeira and Morocco (Zibrowius 1980). All the records given from the Bay of Biscay are from the southern sector (off Spain) further south than 44º13’N, in a bathymetric range of 575− 900 m.