Leptadrillia profunda, 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 : 229-231

Leptadrillia profunda , new species

( Plate 115 )

Type material. Holotype 8.5 x 3.0 mm, J. Moore! (ANSP 465633); 5 paratypes: 7.0 x 2.7, 6.7 x 2.3 & 7.3 x 2.5 mm, from the type locality (ANSP 465634); 7.2 x 2.6 & 7.5 x 2.6 mm, in 366–421 m, SW of Egmont Key, D. Steger! May 1962 (ANSP 306367).

Type locality. W of Tampa Bay, Hillsborough County, W Florida, in 457 m depths.

Other material examined. One additional specimen believed to be this species was examined: 7.6 x 2.7 mm, in 93–94 m, about 20 km WSW of Triángulos Reef, Campeche Bank, Mexico, 20°51.16'N, 92°26.28'W, E. García! aboard R/V Pelican, 10 Jun 2005, 20°51.16'N, 92°26.28'W (EFG 26642).

Range and habitat. Gulf of Mexico (W of Tampa Bay). If the specimen from about 20 km WSW of Triángulos Reef, 20°51.16'N, 92°26.28'W, Campeche Bank is this species, then the range would include that locality. Although most have been taken at 366–457 m, a specimen from off Triángulos Reef believed to be this was taken at a shallower depth of 93– 94 m.

Description. Shell very small (to 8.5 mm in total length), fusiform, translucent, glossy-smooth, with up to 8¾ smooth convex whorls with appressed sutures and peripheries below mid-whorl, the last approximately 56% of the total length; sculpture of axial ribs; aperture narrowly oval, only slightly wider at its widest than anterior canal. Protoconch of 1¾–2 smooth whorls, the first rapidly expanding, not immersed in the second. Axial sculpture of ribs, about the same width as intercostal space, run from suture-to-suture, are slightly opisthocline, recurved on shoulder, number 9–11 on penultimate, 6–8 on last whorl to the varix where they end at the anterior fasciole. Growth striae microscopic, oblique to ribs, recurved in sulcal area. Varix large, about twice the width of preceding ribs, straight, not opisthocline, not recurved in the sulcal area; positioned about ⅓-turn from edge of outer lip.

Spiral sculpture absent, except for 5–7 distinct threads on base and anterior fasciole. Sulcus absent; the only trace of the anal sinus is slightly recurved ribs and growth striae on whorl shoulders. Outer lip thin, with strengthening axial folds sparse; edge of lip forms a round arc, congruent with and from anal sinus to stromboid notch; then bends to follow anterior canal; stromboid notch broad and shallow. Anal sinus is a deep U-shaped notch adjacent to suture, sides parallel; sinus directed somewhat laterally spout-like. Inner lip thin, emarginated, thickest on anterior canal; thinnest on parietal wall, and formed into a weak callus posteriorly at anal sinus. Anterior canal moderately long, open, unnotched. Anterior fasciole not swollen; with spiral threads. Color translucent white to white.

Remarks. Taxonomy. Leptadrillia profunda displays all the characteristics of Leptadrillia : a slender shell with a long anterior canal, ribs extending from suture-to-suture with only a slight change in the sulcal region, and spiral sculpture absent except near and on the anterior fasciole. It is similar to L. lizae in possessing a relatively short anterior canal. Variability. The average total length of seven specimens is 7.40 mm (6.7–8.5 mm) and their average W/ L ratio is 0.355. Identification. Leptadrillia profunda is similar to L. splendida Bartsch, 1934 , L. loria Bartsch, 1934 , L. lizae , new species, and L. campechensis , new species, the latter two are also known to occur in the Gulf of Mexico. From L. splendida it differs in possessing less angular and more evenly rounded whorls, straighter ribs, and a shorter anterior canal. From L. loria it differs in being somewhat larger (7.40 mm versus 6.8 mm in total length), and in possessing a shorter anterior canal. From L. lizae it differs in having less convex whorls and usually fewer ribs (9–11 versus 12–13 on the penultimate whorl). Their protoconchs also differ; the first whorl of L. profunda is not immersed in the second; that of L. lizae is immersed. From L. campechensis it differs in being of a smaller size (7.40 versus 9.56 mm average total length) and in possessing a shorter anterior canal.

Etymology. The Deep Leptadrillia —so named for its acquisition at the bathyal depths of 366– 457 m. From the Latin adjective profunda meaning deep.

Figures

PLATE 115. Leptadrillia profunda, new species. Upper panel. Figs. 1 – 2: holotype, SW of Egmont Key, Hillsborough Co., W Florida (ANSP 465633). Fig. 1: ventral, lateral & dorsal views; Fig. 2: enlarged view of protoconch (not to scale). Lower panel. Figs. 3 – 4: paratypes, SW of Egmont Key, Hillsborough County, W Florida (ANSP 306367); Figs. 5 – 7: paratypes, W of Tampa Bay, Hillsborough County, W Florida (ANSP 465634); Figs. 8 – 9: WSW of Triángulos Reef, Yucatan, Campeche Bank (EFG 26642), ventral view and enlarged view of protoconch, respectively (protoconch not to scale).