Lissodrillia turgida, 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 : 254-256

Lissodrillia turgida , new species

( Plate 129 )

Type material. Holotype 6.2 x 2.8 mm, McGinty! 22 Jun 1951 (UF 249933); 17 paratypes: 3 spec., 4.8 x 2.3, 5.2 x 2.2 & 3.9 x 1.7 mm, in 91 m, Turtle Harbor, N of Key Largo, Miami-Dade Co. (USNM 411272); 3 spec. 7.3 x 2.9, 6.6 x 2.7 & 5.4 x 2.3 mm, in 183 m, off Key West, Florida Keys (USNM 900146); 2 spec., 5.6 x 2.2 & 6.2 x 2.8 mm, in 128–137 m, 170° off Sombrero Light, Florida Keys, McGinty! 22 Jun 1951 (UF 497104); 1 spec., 6.6 x 2.7 mm, in 183 m, off American Shoals, Florida Keys, L.A. Burry! (UF 362367); 7 spec., 4.7 x 2.2, 4.6 x 2.1, 4.4 x 1.9, 4.8 x 2.0, 4.9 x 2.0, 4.7 x 2.1 & 4.5 x 1.9 mm, in 219 m, off Sand Key, Florida Keys, Eolis Sta. 316, 1916 (USNM 411493); 1 spec. 11.7 x 4.0 mm, in 229-238 m, SW of Key West, Monroe Co., Florida Keys (EFG 28297).

Type locality. 170° off Sombrero Light, Florida Keys, in 128– 137 m.

Other material examined. One additional specimen was examined: 6.5 x 2.6 mm, 153 km W of Egmont Key, Hillsborough Co., W Florida, J. Moore! Sep 1962 (H.G. Lee coll.).

Range and habitat. Florida Keys (Key Largo to Key West); W Florida (off Hillsborough Co.). Reported from 73–238 m, most commonly from over 100 m.

Description. Shell very small (to 7.3 mm in total length, exceptionally to 11.7 mm), translucent, glossy, fusiform, anterior truncated, with up to about 7 markedly convex whorls, the last about 60% of total shell length; whorls sculpted with evenly round ribs whose peripheries are at mid-whorl. Shell base tapers rapidly to anterior canal giving the last whorl a round profile; aperture short, oval, with a short anterior canal. Protoconch of 2 smooth, translucent round whorls, the first not immersed in the second. Axial sculpture of evenly spaced, round ribs, about as wide as the intercostal space, that run suture-to-suture on spire whorls, evanesce just below the whorl periphery on the last before fasciole on shell base, opisthocline, 10–13 on penultimate, 9–12 on last to varix. Ribs; slightly narrowed, recurved, and lower on whorl shoulder. Varix like an expanded rib, about twice the width of preceding ribs, ¼-turn or less from the edge of the outer lip, straight not opisthocline like the ribs. Spiral sculpture lacking altogether. Sulcus absent; ribs are lower and recurved below suture, marking previous positions of anal sinus. Outer lip thin, translucent, and projecting only a short distance from varix; one or more strengthening folds may be present. Lip edge forms a low arc from sinus to anterior canal. Stromboid notch not present in examined specimens. Anal sinus deep, U-shaped, outer side divergent; inner edge flared out in mature specimens. Inner lip thin, recumbent, narrow to moderately wide, thinnest on parietal wall, and formed into a weak callus posteriorly at the anal sinus. Anterior canal short but distinctly formed, turned a little to the right when viewed ventrally; unnotched; fasciole not swollen. Color translucent white to off-white.

Remarks. Taxonomy. The position of the varix near the outer lip edge, just behind the anal sinus is unique for the genus. Normally, at least ⅓-turn behind the edge. Other characteristics are more typical of Lissodrillia : small glossy shell with ribs from suture-to-suture, an anal sinus and outer lip that trace a reversed “S”, and the lack of spiral sculpture. Variability. The average total length of 18 specimens is 5.38 mm (3.9–7.3 mm), their average W/ L ratio is 0.429. Identification. Lissodrillia turgida is similar to L. verrillii (Dall, 1881) in possessing very convex whorls, but in L. verrillii they are angular, not evenly round. Lissodrillia turgida has a more open aperture, and a varix positioned closer to the outer lip.

Etymology. The Swollen Lissodrillia , named for its inflated whorls. From the Latin adjective turgidus, feminine turgida , meaning swollen.

Figures

PLATE 129. Lissodrillia turgida, new species. Upper panel. Figs. 1 – 2: holotype (UF 249933), off Sombrero Light, Florida Keys. Fig. 1: ventral, lateral, dorsal views; Fig. 2: enlarged view of protoconch (not to scale). Fig. 3: paratype, SW of Key West, Florida Keys (EFG 28297), apical view, V = varix, L = edge of lower lip. Lower panel. All paratypes, except Fig. 18, all from off Florida Keys. Figs. 4 – 5: Turtle Harbor, N of Key Largo (USNM 411272); Figs. 6 – 11: off Sand Key, Key West (USNM 411493); Figs. 12 – 14: SW of Key West (USNM 900146); Fig. 15: off American Shoals, off Surgarloaf Key (UF 362367); Figs. 16 – 17: off Sombrero Light (UF 497104); Fig. 18: W of Egmont Key, W Florida (H. G. Lee coll.).