Leptadrillia campechensis, 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 : 213-215

Leptadrillia campechensis , new species

( Plate 104 )

Leptadrillia splendida Bartsch, 1934 : Rice & Kornicker (1965: 126, pl. 7, fig 1 [Campeche Bank]) may be this species.

Type material. Holotype 12.8 x 4.3 mm, E. García! aboard R/V Pelican, 10 Jun 2005, (ANSP 465240). 28 paratypes: 12 spec., 13.4 x 4.3, 13.2 x 4.4, 8.7 x 3.1 & 8.0 x 2.9 mm (EFG 26645), 8.0 x 2.9, 10.5 x 3.7 & 13.0 x 3.8 mm (UF 470327), and 7.6 x 2.8, 6.0 x 2.4, 8.4 x 2.9, 7.5 x 2.7 & 8.5 x 2.8 mm (UF 381580), in 73–77 m, Campeche Bank, Mexico, 20°00.35′N, 92°26.10′W, E. García! aboard R/V Pelican, 11 Jun 2005; 9 spec., 7.5 x 2.7, 8.6 x 2.7, 7.9 x 2.6, 10.4 x 3.4, 11.3 x 3.5 & 10.0 x 3.2 mm (UF 470326), 12.1 x 4.0, 12.2 x 3.7 & 9.9 x 3.3 mm (EFG 26636), in 63–65 m, Campeche Bank, Mexico, 20°51.49'N, 92°21.44'W, E. García! aboard R/V Pelican, 10 Jun 2005; 4 spec., 10.3 x 3.2, 9.1 x 3.1, 9.1 x 3.2 & 7.8 x 3.0 mm, in 77–81 m, Campeche Bank, Mexico, 20°52.40'N, 92°24.83'W, E. García! aboard R/V Pelican, 10 Jun 2005 (EFG 26547); 3 spec., 8.5 x 2.9, 8.5 x 2.9 & 8.1 x 2.8 mm, in 107–108 m, about 20 km NW of Arenas Cay, 22°16.28'N, 091°30.42'W, E. García! aboard R/V Pelican, 16 Jun 2005 (EFG 26548).

Type locality. Campeche Bank, Mexico, 20°51.49'N, 92°21.44'W, in 63– 65 m.

Range and habitat. Mexico (Campeche Bank). Reported from 63–108 m, on a mud bottom.

Description. Shell small (to 13.4 mm in total length), glossy and translucent, narrowly fusiform; whorls moderately convex with peripheries just below mid-whorl, up to a total of 10¾ whorls, last approximately 57% of total length including anterior canal; teleoconch with axial ribs; aperture narrow, long. Protoconch of 1½–2 evenly expanding, glossy, smooth whorls, the first only a little smaller in diameter than the second. Axial sculpture of sigmoid ribs that run from suture-to-suture, highest, widest, and hooked near whorl midpoint; low, narrow, and curved in sulcus such that the leading face is concave. Ribs knob-like on first three teleoconch whorls, becoming longer on subsequent ones, are narrower than their intercostal space, evanesce on last whorl at anterior fasciole except mostly obsolete on parietal wall; ribs number 9–11 on penultimate and 6–10 to the varix on last whorl. Very fine, microscopic growth striae present throughout. Varix runs from suture to anterior fasciole, larger than and 2–3 times the width of the preceding ribs; positioned about ¼-turn from the edge of the outer lip. Spiral sculpture absent, except for approximately 9 spiral threads on the anterior fasciole. Sulcus narrow, marked by lower, narrower ribs curved to reflect the outline of the anal sinus. Outer lip thin, translucent, strengthened by up to 4 axial folds. Lip edge forms a low arc from the anal sinus to stromboid notch; bends inward posteriorly. Stromboid notch shallow. Anal sinus on shoulder, close to but separate from suture by parietal lobe, notch deep, U-shaped, inner edge flared, and outer lip directed somewhat laterally giving the sinus a spout-like appearance. Inner lip thin, recumbent, margined, thicker anteriorly along anterior canal, and posteriorly as a parietal lobe. Anterior canal long, straight, open, anterior end turned slightly to the right, when viewed ventrally; end unnotched. Color white, outer lip, and rib interspaces translucent.

Remarks. Taxonomy. Leptadrillia campechensis has all the important characteristics of the genus: a narrow, spindly shell with a long anterior canal, narrow ribs that extend from suture-to-suture, and the absence of spiral sculpture, except for threads or ridges on the anterior fasciole. Variability. The 29 measured specimens have an average length of 9.56 mm (6.0– 13.4 mm), and an average W/ L ratio of 0.341. Identification. Leptadrillia campechensis is closest to L. splendida Bartsch, 1934 and similar to L. loria Bartsch, 1934 , L. lizae , new species, and L. histriata , new species. Leptadrillia campechensis has slightly more convex whorls, proportionally taller spire, and more oblique ribs than L. splendida . It also has a rounder last whorl. From L. loria it differs in being larger (average total length is 9.85 versus 6.16 mm) and having a proportionately longer anterior canal and larger protoconch. Leptadrillia lizae has straighter ribs and a shorter anterior canal. From L. histriata it differs in possessing fewer ribs (9–11 versus 13–15 on the penultimate whorl), and round-crested ribs, not ridged ones.

Etymology. The Campeche Leptadrillia —named for the Campeche Bank, the area of its known occurrence.

Figures

PLATE 104. Leptadrillia campechensis, new species. Upper panel. Fig. 1: holotype, Campeche Bank, Mexico (ANSP 465240), ventral, lateral & dorsal views. Fig. 2: enlarged view of protoconch of specimen from Campeche Bank, Mexico (EFG 26548). Fig. 3: apical view of specimen from Campeche Bank, Mexico, V = varix, L = edge of outer lip (EFG 26645). Lower panel, paratypes from Campeche Bank, Mexico. Figs. 4 – 5: EFG 26645; Fig. 6: UF 470327; Figs. 7 – 8: EFG 26636; Fig. 9: EFG 26547; Figs. 10 – 12: UF 470326; Fig. 13: EFG 26547; Fig. 14: EFG 26548; Fig. 15: EFG 26645; Figs. 16 – 17: EFG 26548; Fig. 18: EFG 26547.