Leptadrillia guianensis, Fallon, Phillip J., 2016

Fallon, Phillip J., 2016, Taxonomic review of tropical western Atlantic shallow water Drilliidae (Mollusca: Gastropoda: Conoidea) including descriptions of 100 new species, Zootaxa 4090 (1), pp. 1-363 : 217-218

Leptadrillia guianensis , new species

( Plate 106 )

Type material. Holotype, live-taken, 17.1 x 5.5 mm (decollate), 1 Aug 2014, (MNHN IM-2013-56290); one paratype 15.5 x 5.7 mm (apex gone) from type locality (MNHN IM-2000-31085). Barcode information for the holotype is tabularized below:

MNHN Catalog Number Station GenBank accession number BOLD accession number IM-2013-56290 (hol) CP4367 KT782769 TEMPO042-15 Type locality. Off French Guiana, 07°09'N, 53°01'W, in 351–354 m ( GUYANE 2014 Sta. CP4367).

Range and habitat. Known only from the type locality.

Description. Shell small (both types are incomplete but up to at least 18 mm in total length), fusiform, smooth; holotype with 7 remaining convex whorls, with appressed sutures and shouldered below sulcus; sculpture of axial ribs; aperture narrowly oval. Protoconch unknown, eroded away on holotype. Axial sculpture of narrow ribs that evanesce just before each succeeding whorl’s suture and on the last whorl below shell periphery on ventrum and at anterior fasciole on shell dorsum, reduced and recurved on whorl shoulders. Ribs opisthocline, 12 on penultimate, 10 on last whorl to the last rib, intercostal space about twice the width of the ribs. Rib crests round. Growth striae microscopic, oblique to ribs, recurved in sulcal area. Varix not well developed; last few ribs on last whorl are narrower and more prominent than previous ones. Spiral sculpture absent, except for spiral threads on anterior fasciole. Sulcus indistinct but shoulder about ¼- to ⅓-whorl height with reduced to obsolete ribs. Outer lip thin, edge forms a low arc from anal sinus to stromboid notch; surface reinforced with two strong axial folds. Stromboid notch very shallow. Anal sinus a moderately deep notch with divergent sides. Inner lip narrow, margined, erect along columella, recumbent on parietal wall, and formed into a weak callus at anal sinus. Anterior canal long, open, curved to the right when viewed ventrally and weakly notched. Anterior fasciole not swollen; with 8 weak spiral threads. Color of holotype light golden brown, darkest between ribs, with white anterior fasciole and aperture.

Remarks. Taxonomy. Leptadrillia guianensis is large for the genus but is otherwise typical in possessing spiral sculpture only on the anterior fasciole, a long anterior canal, and narrow ribs. Identification. Leptadrillia guianensis is unique for its size and color pattern. It is similar in shape to L. flavomaculata , new species but larger (approximately 18 versus 12.3 mm). Leptadrillia luciae , new species has less convex whorls and is also smaller (to about 11 mm). The size of L. lucaya , new species (16.5 mm) approaches L. guianensis but that species is translucent white and narrower (W/L = 0.236 versus approximately 0.322). Leptadrillia guianensis stands out from all other members of the genus-group for its size and color pattern. In addition, it is the only species of Leptadrillia reported from bathyal depths of the southeasten Caribbean, all factors believed to merit its description.

Etymology. The Guianese Leptadrillia , named after the country of the type locality, French Guiana.

Figures

PLATE 106. Leptadrillia guianensis, new species. Fig. 1: holotype, off French Guiana (MNHN IM- 2013 - 56290), ventral, lateral & dorsal views. Figs. 2 – 3: paratype, from type locality (MNHN IM- 2000 - 31085). Fig. 2: ventral & lateral views; Fig. 3: apical view.