Calliostoma leptophyma Dautzenberg & Fischer, 1896

Hoffman, Leon, Beuck, Lydia, Heugten, Bart Van, Lavaleye, Marc & Freiwald, André, 2019, Last snails standing since the Early Pleistocene, a tale of Calliostomatidae (Gastropoda) living in deep-water coral habitats in the north-eastern Atlantic, Zootaxa 4613 (1), pp. 93-110 : 104-106

Calliostoma leptophyma Dautzenberg & Fischer, 1896

( Figs 35–43 )

Calliostoma leptophyma Dautzenberg & Fischer, 1896: 482 pl. 21 fig. 6

Type material. Not seen, unknown number, probably empty shell. Rocky ground west of Faial, Azores, Princesse- Alice-1895-77, at 845 m. Scleractinians were also found at this location.

Material examined. Moroccan Slope, 64PE284/GeoB 12712, 35.368°N, 06.903°W, 685 m, 2 shells in Pleistocene thanatocoenosis, grab, 23-II-2008.

Porcupine Basin, Belgica Mound Province, Castor Mound, M61-1/223, 51.430°N, 11.794°W, 1029 m, one shell, box corer, 23-IV-2004; Poseidon Mound, M61-3/577 (GeoB 9230), 51.452°N, 11.747°W, 899 m, nine shells, box corer, 7-VI-2004; Hovland Mound Province , Propeller Mound, POS292/562 (GeoB 8039), 52.137°N, 12.768°W, 850 m, one shell, box corer, 25-VII-2002 ; North Porcupine Bank , Twin Mounds, PS 64/283, 53.515°N, 14.353°W, 966 m, two shells, box corer, 13-VI-2003 .

Rockall Bank, Logachev Mounds, Moundforce2004/37, 55.497°N, 15.802°W, 557 m, 19 shells, box corer, 02- IX-2004 ( Fig. 38 ); Moundforce2004/41C, 55.436°N, 16.116°W, 784 m, three shells, box corer, 05-IX-2004 ( Figs 41 –44); HERMES2005/23, 55.503°N, 15.786°W, 167 m, one shell, box corer, 27-VI-2005; HERMES2005/34, 55.445°N, 16.07°W, 767 m, 23 shells, box corer, 28-VI-2005; HERMES2006/10C, 55.500°N, 15.799°W, 587 m, seven shells, box corer, 24-VI-2006; HERMES2006/12, 55.452°N, 15.766°W, 1091 m, one shell, box corer, 24-VI- 2006 ( Figs 35–37 ); HERMES2006/23A, 55.500°N, 15.799°W, 587 m, seven shells, box corer, 26-VI-2006 ( Fig. 39 ); HERMES2006/28A, 55.498°N, 15.810°W, 588 m, five shells, box corer, 27-VI-2006; HERMES2006/65, 55.452°N, 15.766°W, 1087 m, one shell, box corer, 02-VII-2006.

Hatton Bank, HERMES2008/92, 58.734°N, 18.718°W, 822 m, three shells, video box corer, 02-VII-2008.

Azores, M151/47 (GeoB 23147), 38.031°N, 29.426°W, 830 m, one shell, grab, 14-X-2018; M151/53-2 (GeoB 23153-2), 37.659°N, 25.789°W, 831 m, one shell, grab, 15-X-2018; M151/69-2 (GeoB 23169-2), 37.659°N, 25.789°W, 898 m, one shell, grab, 17-X-2018.

Atlantis Seamount, M151/89 (GeoB 23404), 33.971°N, 30.206°W, 677 m, one shell, grab, 21-X-2018.

Little Meteor Seamount, M151/119 (GeoB 23434-4, Fig. 40 ), 29.654°N, 29.015°W, 876 m, one live specimen in Lophelia rubble, ROV sample, 27-X-2018.

Description. We refer to the description given by Dautzenberg & Fischer (1896) and add details on the protoconch:

The protoconch is similar to that of C. bullatum , comprising 0.8 globular whorls with a rounded varix. Sculpture hexagonally reticulated on a smooth background ( Fig. 37 ). Hexagonal cells loosely arranged in about 11 spiral rows and about 30 axial rows with a diameter of about 0.04 mm each; central pits round with a flat base.

Distribution. Calliostoma leptophyma is found from the Hatton, Rockall and Porcupine Banks in the north, the Azorean Seamounts in the west to the continental slope off Western Sahara in the south. Within this study, shells were found in the bathymetrical range of 557–1091 m and one live specimen at 876 m.

Beck et al. (2003) reported shells from the Seine and Gettysburg Seamounts. Rolán & Suárez (2007) mentioned three live specimens from the Galicia Bank at 769–1000 m and one live specimen off Cedeira, NW Spain at 600 m. Le Duff (2015) mentioned two live specimens from the Bay of Biscay at 519– 650 m. Locard (1898) reported specimens from off Western Sahara as Zizyphinus laquatus (Talisman1883/DR 71, 640 m) and Zizyphinus oppansus (Talisman1883/DR 63, 640 m).

Remarks. The frequent occurrence of Calliostoma leptophyma in coral rubble sampled at all DWC locations and one live specimen from the Little Meteor Seamount suggest a close association with DWC habitats. It displays a considerable morphological variability. A syntype of the synonymous Zizyphinus laquatus Locard 1898 from off Western Sahara (MNHN-IM-2000-31194) is very similar to the holotype but it has fewer spiral ribs with beads. A syntype of the synonymous Zizyphinus oppansus Locard, 1898 from off Western Sahara (MNHN-IM-2000-31252) has a nearly smooth and flat base with a strong keel on the body whorl. In contrast, the holotype has a more rounded outline and flattened spiral ribs on the base of the body whorl.

The differences between the various Calliostoma species have been discussed above ( C. bullatum ).

Two syntypes of C. cleopatra have been described from off Western Sahara at 1435 m (MNHN-IM-2000- 31095); this species is more slender and has regularly spaced spiral ribs on the upper whorl face, on the wellrounded periphery and on the base. Moreover, it has more pronounced beads on the spiral ribs. Future physiological and molecular studies may prove this species to be synonymous with C. leptophyma . Specimens reported under the name C. cleopatra ( Locard, 1898) by Hoffman et al. (2011) are considered to represent C. leptophyma herein.

Figures

FIGURES 35–43. Calliostoma leptophyma. 35–37. HERMES2006/12, 35–36. H 1.0 mm, W 1.1 mm. 37. Protoconch W 0.59 mm, T 0.45 mm, scale bar 0.1 mm. 38. Moundforce2004/37, H 2.2 mm, W 2.3 mm, protoconch W 0.56 mm, T 0.43 mm. 39. HERMES2006/23A, H 2.9 mm, W 2.9 mm, protoconch W 0.57 mm, T 0.43 mm. 40. M151/GeoB 23434-4, live-collected, H 13 mm, W 14 mm. 41–43. Moundforce2004/41C, H 22 mm, W 23 mm.