Discaclis lamellata, Ortega & Gofas, 2019

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 : 528

Discaclis lamellata n. sp.

( Fig. 11 D-J)

urn:lsid:zoobank.org:act:E31801E2-E7D1-4E48-BDEF-5CCE831C057A

TYPE MATERIAL. — Holotype. sh., MNHN-IM-2000-34257 . Paratypes. 16 sh., MNHN-IM-2000-34258 from SEAMOUNT 2, DW130 .

TYPE LOCALITY. — Off NW Gran Canaria, 28°08.95’N, 15°53.11’W / 28°09.06’N, 15°52.92’W, 655- 660 m.

ETYMOLOGY. — An adjective formed from the Latin lamella, a small blade, alluding to the lamellae inside the umbilicus.

DESCRIPTION

Shell very small, with a low spire and a blunt, protruding apex and with a deep and rather wide umbilicus. Larval shell globular, smooth and glossy, consisting of about 1 1/4 whorls with diameter 320 to 330 µm, demarcated from teleoconch by a distinct scar (difficult to see in optical microscopy due to transparency, conspicuous under SEM). Teleoconch of 1 1/4 whorl in specimens about 0.9 mm in diameter, up to 2 1/4 whorls in the largest specimens, with a narrow subsutural keel running very close to the suture and giving it a channelled aspect, with another blunt keel delimiting the abapical area around the umbilicus. Sculpture of numerous indistinct growth lines and, on the subsutural keel, of microscopic spiral striae. Within the umbilicus, 7-8 raised lamellae corresponding to earlier positions of outer lip. Aperture distinctly opisthocline, strongly expanded and flaring, especially in lower part prolonging the columellar edge. Outer lip not thickened. Maximum diameter (including the flaring lip) 0.9 to 1.3 mm (holotype 0.75 mm height × 1.0 mm diameter).

REMARKS

Discaclis lamellata n. sp. differs from the only species of the genus known so far, D. canariensis ( Fig. 11 A-C), in being twice as high with the same diameter, in having a considerably narrower umbilicus, and in having raised lamellae inside the umbilicus, which represent former stages of growth of the apertural lip. Discaclis canariensis is a shallow-water species with a type locality at 125 m and a record as shallow as 12 m in a submarine cave ( Martínez et al. 2005). The specimen from Madeira figured by Segers et al. (2009: pl. 14, fig. 5) is more similar to Discaclis lamellata n. sp. (albeit larger, 1.5 mm) than to Discaclis canariensis ; it is stated to originate from only 30 m depth but the authors suspect that it could be “of subfossil origin”. It is possibly a third, different species, or alternatively Discaclis lamellata n. sp. is not a deep-sea species but the shells collected here have been transported downslope.

Figures

FIG. 11. — A-C, Discaclis canariensis Moolenbeek & Warén, 1987, shell from DW133 (diameter 1.2 mm); D-J, Discaclis lamellata n. sp.: D-F, holotype (sh.) from DW130 (diameter 1.0 mm); G, paratype (sh.), same locality (diameter 0.95 mm); H, protoconch of another paratype; I, protoconch of another paratype in apical view; J, microsculpture on the shoulder, same shell as I. Scale bars: H, I, 100 µm; J, 20 µm.