Calliostoma maurolici (G. Seguenza, 1876)

(Figs. 21–34)

Trochus (Zizyphinus) maurolici G. Seguenza, 1876: 184

Gibbula obesula Locard, 1898: ex P. Fischer ms.; vol. 2, 47–49, pl. 3 figs 1–4

Gibbula maurolici: L. Seguenza 1903: 460 –461, tab. XVII, fig. 17

Calliostoma maurolici: Micali & Villari 1989: 350, 360–362, figs 9–11

Calliostoma maurolici: Di Geronimo & La Perna 1997: 418, synonymised Gibbula obesula Locard, 1898

Type material. Type locality is a Calabrian (Early Pleistocene) outcrop near Messina, Sicily. The type material of Trochus maurolici is lost. Syntypes of Gibbula obesula from Atlantic Morocco, off Cape Spartel, are retained in MNHN: MNHN-IM-2000-31248, Talisman- 1883-10, 717 m (Chagnoux 2017).

Material examined. Moroccan Slope, 64PE284/GeoB 12712, 35.368°N, 06.903°W, 685 m, 10 shells in Pleistocene thanatocoenosis, grab, 23-II-2008; 64PE284/GeoB 12729, 35.181°N, 06.942°W, 754 m, 18 shells in Pleistocene thanatocoenosis, video box core, 26-II-2008.

Galicia Bank, VH 97/61, 42º874°N, 11.823°W, 1080 m; six shells in pteropod ooze, grab, 08-IV-1997 .

Porcupine Basin, Belgica Mound Province, Therese Mound, CARACOLE/PL124-2, 51.431°N, 11.754°W, 807–1016 m, live individuals observed, 01-VIII-2001; PS64/278 (ROV), live individuals observed, 51.456°N, 11.736°W, 992 m, 10-VI-2003; M61-1/245 (DOS Lander), live individual observed, 51.456°N, 11.753°W, 806 m, 25-IV-2004; Galway Mound, M61-3/550 (GeoB 9203, ROV), 51.445°N, 11.751°W, 892 m, live individuals observed, 05-VI-2004; M61-3/552 (GeoB 9205), 51.451°N, 11.752°W, 810 m, one shell, box corer, 02-VI-2004; POS316/528, 51.438°N, 11.740°W, 916 m, one shell, box corer, 11-VIII-2004; Poseidon Mound, M61-3/575 (GeoB 9228), 51.462°N, 11.693°W, 752 m, one shell, box corer, 07-VI-2004; POS292 /606 (GeoB 8083), 51.460°N, 11.700°W, 670 m, seven shells, box corer, 01-XIII-2002; POS292 /607 (GeoB 8084), 51.460°N, 11.700°W, 670 m, two shells, box corer, 01-XIII-2002; POS400 /GeoB 14548 (ROV5), 51.456°N, 11.707°W, 795– 682 m, multiple live specimens on rock, 11-VII-2010; Pollux Mound, POS400/GeoB 14526, 51.416°N, 11.762°W, 905 m, six shells, grab, 06-VII-2010; POS400/GeoB 14543 (ROV2), 51.335°N, 11.697°W, 847– 723 m, live individuals feeding on live Lophelia pertusa and on rocks with hydroids, 09-VII-2010 ; POS400/GeoB 14544 (ROV3), 51.339°N, 11.699°W, 793–818 m, live individuals observed, 09-VII-2010 .

Hovland Mound Province, Propeller Mound, POS265/497 (GeoB 6737), 52.156°N, 12.768°W, 771 m, one live specimen, dredge, 26-IX-2000; CARACOLE/ PL126-4, 52.232°N, 12.758°W, 670–869 m, live individuals observed, 04-VIII-2001;

North Porcupine Bank, CARACOLE/PL129-7, 53.775°N, 13.971°W, 598–671 m, live individuals observed, 08- VIII-2001; PS64/282 (ROV), live individuals observed, 53.086°N, 14.806°W, 794 m, 12-VI-2003; Twin Mounds, PS64/283-3, 53.515°N, 14.353°W, 966 m, three shells, box corer, 13-VI-2003; PS64/297 (ROV), live individuals observed, 53.765°N, 13.992°W, 795 m, 15-VI-2003; Connaught Mound, M61-3/632 (GeoB 9285, ROV), 53.517°N, 14.367°W, 876 m, live individuals observed, 15-VI-2004.

Rockall Bank, SE Rockall Bank, Logachev Mounds, Moundforce2004/37, 55.497°N, 15.802°W, 557 m, five shells, box corer, 02-IX-2004 (Figs 21–24); HERMES2006/10C, 55.500°N, 15.799°W, 587 m, two shells, box corer, 24-VI-2006; HERMES2006/12, 55.452°N, 15.766°W, 1091 m, one shell, box corer, 24-VI-2006; HERMES2006/ 23A, 55.500°N, 15.799°W, 587 m, 10 shells, box corer, 26-VI-2006; HERMES2006/65, 55.452°N, 15.766°W, 1087 m, five shells, box corer, 02-VII-2006; West Rockall Bank, Franken Mound, M 61-3/603 (GeoB 9256), 56.503°N, 17.306°W, 629 m, one live specimen, box corer, 11-VI-2004 (Figs 26–28) ; M61-3/628 (GeoB 9281, ROV), 56.498°N, 17.303°W, 651 m, live individuals observed, 13-VI-2004; Kiel Seamount, POS316/499, 56.699°N, 17.506°W, 824 m, one live specimen, box corer, 07-VIII-2004.

Hatton Bank, HERMES2008/117, 58.762°N, 18.757°W, 958 m, one shell, video box corer, 06-VII-2008.

Azores, M151/69-1 (GeoB 23169), 37.659°N, 25.789°W, 595 m, one shell, grab, 17-X-2018; M151/81 (GeoB 23181), 37.659°N, 25.789°W, 599 m, one shell, box corer 19-X-2018.

Great Meteor Seamount, M151/110 (GeoB 23425-4), 29.565°N, 28.339°W, 948 m, one shell, ROV sample, 25- X-2018; M151/114 (GeoB 23429-5), 30.087°N, 28.727°W, 895 m, one shell, ROV sample, 26-X-2018; M151/114 (GeoB 23429-7), 30.086°N, 28.726°W, 902 m, one shell, ROV sample, 26-X-2018.

Greece, Rhodes, St. Paul’s Bay, Fossil - Mid Pleistocene, limestone outcrop (private collection A. Freiwald, Fig. 25).

Description. We refer to the decriptions given by Seguenza (1876) and Locard (1898) and add details on the protoconch and the animal in the following.

The protoconch is similar to that of C. bullatum; 0.8 globular whorls ending with a rounded varix. The sculpture is hexagonally reticulated on a smooth background (Fig. 24). The hexagonal cells are arranged in about 15 spiral rows with a height of about 0.016 mm each.

The animal has an oblong snout with a swollen head with two long and pointed cephalic tentacles. Small black eyes on short ommatophores are present behind the base of the cephalic tentacles. A set of epipodial sensory tentacles is visible on the dorsal side of the foot below the shell. The living animal is pinkish white. The operculum is brown, translucent, thin, chitinous, spirally developed.

Distribution. Fossil in bathyal Early to Middle-Pleistocene formations in southern Italy (SW Calabria, NE Sicily) (G. Seguenza 1876; Barrier et al. 1996), Rhodes, Greece (own data) and on the Moroccan continental slope (Foubert 2007; Foubert et al. 2008). The fossil records from the Early Pleistocene suggest that the species has been living for about 2.5 million years.

Our study includes recent specimens from the Porcupine Basin, Rockall Bank, Azores and Great Meteor Seamount in DWC, dead at 587–1087 m, alive at 598–1016 m (Fig. 1).

Locard (1898) reported syntypes of the synonymised Gibbula obesula off western Morocco (Talisman- 1883- 10, 717 m and Talisman- 1883-71, 640 m). Ibarrola et al. (2011) reported a live specimen in DWC off NW Spain. Reynell (1909) reported live specimens in the Bay of Biscay (Huxley- 1906-7, 812 m, 24 live specimens and Huxley- 1906-13, 753 m, one live specimen). These old records derive from samples rich in Lophelia pertusa and Madrepora oculata .

The species has a wide NE Atlantic distribution, associated with DWC, from the Rockall Bank in the north to the continental slope of Morocco in the south and the Azorean Seamounts in the west.

Remarks. Calliostoma maurolici is common in the NE Atlantic. The differences between the various Calliostoma species are given in the discussion of C. bullatum .

Our observations from ROV surveys found the species grazing on dead Scleractinia (Figs 29–30), live Madrepora oculata (Fig. 31), live Actiniaria ( Phelliactis hertwigi Simon, 1892, Fig. 33) and on hardground with epiliths including hydroids (Figs 32, 34). The animal is common in live Lophelia pertusa and Madrepora oculata communites in the Belgica Mound Province, SE of the Porcupine Bank (Freiwald & Beck 2007; Beuck 2008; this paper).