Aclis attenuans Jeffreys, 1883

Ortega, José Rafael & Gofas, Serge, 2019, The unknown bathyal of the Canaries: new species and new records of deep-sea Mollusca, Zoosystema 41 (26), pp. 513-551 : 526

Aclis attenuans Jeffreys, 1883

( Fig. 10 A-F)

MATERIAL EXAMINED. — 6 sh., SEAMOUNT 2, DW130 . — 7 sh., Alboran Sea, Djibouti Banks, 36°21.08’N,‰ 3°58.58’E / 36°21.06’N, 3°58.07’E, 349-365 m, Spanish Institute of Oceanography cruise DP0409, haul BT04 . — 1 sh., Gulf of Cadiz, Gazul mud volcano, 36°33,6’N 6° 56.3’W / 36°33.7’N, 6°56,3’ W, 428 m, cruise INDE- MARES CHICA 0610 , haul DA11 .

REMARKS

Bouchet & Warén (1986) recognized three similar species in deep water of the Atlanto-Mediterranean area: Aclis walleri Jeffreys, 1867 described from off Shetland (140 m), Aclis attenuans Jeffreys, 1883 described from off Crete (70- 120 fathoms = 128-219 m) and Aclis sarsi Dautzenberg & H. Fischer, 1912 described from off Norway (440 m). The Mediterranean A. attenuans differs from the Atlantic A. walleri in being smooth, without the axial riblets of A. walleri , in having a smaller (2-3 mm vs 4-5 mm high) and broader shell. Aclis sarsi differs from both in having only one protoconch whorl instead of more than two in the other two species Bouchet & Warén further reported a single shell from the Canaries as probably representing a new species, but refrained from describing it as the specimen was not in good enough condition. It was stated as having “the same kind of apical whorls as A. sarsi but the shape is similar to A. attenuans ”. The SEAMOUNT 2 material contains additional shells of the same Canarian species but this (including the specimen figured by Bouchet & Warén) has a little more than two protoconch whorls and is therefore similar to Aclis attenuans and does not have the paucispiral protoconch of Aclis sarsi . Admittedly, the Canarian specimens are slightly larger (3.7 mm instead of usually less than 3 mm for Mediterranean specimens) and the protoconch is also slightly larger in proportion, but are here taken as a range extension of Aclis attenuans and new record to Canary Islands waters.

Figures

FIG. 10. — A, Aclis attenuans Jeffreys,1883,shell from Alboran Sea,Djibouti Banks,349-365 m (height 2.8 mm); B, C, shell from the Gulf of Cadiz (height 3.0 mm); D-F, shell from DW130 (height 3.7 mm); scanning electron micrograph of the protoconch (F). Scale bar: 100 µm.