Lissodrillia lactea, 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 : 244-246

Lissodrillia lactea , new species

( Plate 124 )

Type material. Holotype 6.8 x 2.8 mm (UF 470328); 14 paratypes: 1 spec., 5.8 x 2.3 mm, in 146–183 m, off Hillsboro Broward Co., E Florida, L.A. Burry! (UF 362379); 3 spec., 5.5 x 2.1, 5.5 x 2.0 & 5.4 x 2.1 mm, in 24 m, E of Pacific Reef Light, Miami-Dade Co., E Florida (USNM 900149); 3 spec., 6.4 x 2.3, 6.0 x 2.3 & 5.7 x 2.2 mm, in 137 m, off Palm Beach, Palm Beach Co., E Florida, T. McGinty! 15 Dec 1949 (UF 250571); 7 spec., 5.1 x 2.0, 5.4 x 2.0, 5.5 x 2.0, 3.0 x 1.4, 3.4 x 1.5, 3.6 x 1.7 & 4.5 x 1.8 mm, in 84–107 m, off Boynton Beach, Palm Beach Co., E Florida, M. Glickstein! Apr 1986 (UF 470330).

Type locality. Off Port Canaveral, Broward Co., E Florida. Specimen from scallop tailings; depth of collection unknown.

Other material examined. An additional 64 specimens were examined: E Florida: 6 spec., 6.2 x 2.4, 5.5 x 2.1, 6.3 x 2.4, 6.5 x 2.4 & 6.3 x 2.4 mm, from beach renourishment sand, Atlantic Dunes Park, Delray Beach, Palm Beach Co., J. Lightfoot! 1972 (UF 470331); 2 spec., 6.0 x 2.4 & 5.2 x 2.2 mm, in 146–183 m, off Yamato, Palm Beach Co., L.A. Burry! (UF 362369); 2 spec., 6.1 x 2.6 & 5.2 x 2.3 mm, in 137 m, off Palm Beach, Palm Beach Co., McGinty! aboard R/V Triton , 9 Dec 1949 (UF 251128); 3 spec., 4.5 x 2.1, 5.5 x 2.3 & 6.1 x 2.1 mm, in 229 m, off Bath & Tennis Club, Palm Beach Co., Palm Beach Co., McGinty! 8 Mar 1951 (UF 219626); 13 spec., 6.0 x 2.4, 5.1 x 2.1, 5.1 x 1.9, 5.2 x 2.2, 5.3 x 2.2, 5.5 x 2.3, 5.2 x 2.2, 5.0 x 2.1, 4.9 x 1.9, 4.5 x 2.0, 5.1 x 2.0, 5.3 x 2.2 & 5.5 x 2.3 mm, in 183 m, N of radio towers, Palm Beach, Palm Beach Co., McGinty! aboard R/V Triton , 23 Jan 1950 (UF 228596); 12 spec., the best 3: 5.7 x 2.1, 6.0 x 2.0 & 5.3 x 2.0 mm, in 146–183 m, off Palm Beach, Palm Beach Co., 1940 (UF 228418); 2 spec., 5.5 x 2.1 & 5.8 x 2.1 mm, in 73–110 m, off Hillsboro, Broward Co., L.A. Burry! (UF 368207). Florida Keys: 2 spec., 6.0 x 2.5 & 5.2 x 2.1 mm, in 61 m, off Key Vaca, Marathon, T. Kalafut! 1978 (UF 470329); 19 spec., the best 8: 5.5 x 2.2, 5.1 x 2.0, 5.9 x 2.1, 5.0 x 1.9, 5.4 x 2.1, 5.1 x 1.9, 3.6 x 1.8 & 5.0 x 2.0 mm, in 101–128 m, off Looe Key, L.A. Burry! (UF 363833, UF 363834); 3 spec., 3.9 x 1.7, 3.8 x 1.7 & 5.5 x 2.2 mm, in 183 m, SW of Key West, Ogle! 1974 (USNM 900151).

Range and habitat. E Florida (Palm Beach Co.; Broward Co.); Florida Keys. Reported from 24–229 m, most in the range of 61– 183 m.

Description. Shell very small (to 6.8 mm in total length) fusiform, glossy, whorls convex, peripheries slightly below mid-whorl, number to about 7½, the last about 56% of total length. Sculptural element consists of axial ribs; aperture rather short and wide, with a short, distinct anterior canal and a deep anal notch. Protoconch of 1¾ smooth round whorls, the first partially immersed in the second such that the protoconch appears round. Axial sculpture of ribs that extend from suture-to-suture on spire whorls, and evanesce before the anterior fasciole on the last. Ribs round-crested, opisthocline, recurved posteriorly, number 6–10 on penultimate, 3–6 on last to varix, and are about as wide as the intercostal space. Growth striae microscopic. Varix broad, low, positioned about ⅓-turn from edge of outer lip. Spiral sculpture absent. Sulcus absent; recurved and slightly reduced ribs, and recurved growth striae just below suture mark past positions of the anal sinus. Outer lip thin, smooth, with 1–2, or without axial folds, when present often on edge of outer lip; edge of anal sinus and outer edge of lip trace a reversed “S”. Lip edge is bent slightly inward; stromboid notch not evident. Anal sinus a deep notch positioned adjacent to the suture, with a round apex and divergent outer edge. Edge of sinus projects outward near edge of outer lip. Inner lip narrow, recumbent except at anterior end where it is pinched up along canal. Lip is formed into a low, weak callus at anal sinus. Anterior canal well defined but short, bent to the right of the shell axis when viewed ventrally; end not notched, or very slightly so in some individuals. Anterior fasciole not swollen. Color white to light golden brown, protoconch and first teleoconch whorl may be darker, especially pink in white forms.

Remarks. Taxonomy. Lissodrillia lactea has the combination of characteristics unique to Lissodrillia : a small glossy shell with ribs that extend from suture-to-suture, an anal notch with a divergent outer edge, a short anterior canal, and no spiral sculpture.

Variability. The 59 measured specimens have an average total length of 5.32 mm (3.0– 6.8 mm) and an average W/ L ratio of 0.401. Color varies from white to a light golden brown; apices may be pink or brown. Identification. Lissodrillia lactea closely resembles L. arcas , new species, L. robusta , new species, and L. schroederi (Bartsch & Rehder, 1939) . From L. arcas it can be distinguished by its shorter anterior canal (and less drawn out base), and by its wider aperture. From L. robusta it can be distinguished by its more subdued ribs and narrower last whorl. It is white in color, not the usual yellowish brown to pinkish of L. robusta . From L. schroederi it can be distinguished by its more convex whorls, less distinct ribs, and usually fewer ribs (6–10 versus 10–11 on the penultimate whorl).

Etymology. The Milky Lissodrillia , named for its milky-white base shell color. Lactea is the feminine form of the Latin adjective lacteus, meaning milky.

Figures

PLATE 124. Lissodrillia lactea, new species. Upper panel. Figs. 1 – 3: holotype, off Port Canaveral, Broward Co., E Florida (UF 470328). Fig. 1: ventral, lateral & dorsal views; Fig. 2: enlarged view of protoconch (not to scale); Fig. 3: apical view, V = varix, L = edge of outer lip. Lower Panel, specimens from various locations. Fig. 4: paratype, off Hillsboro, Broward Co., E Florida (UF 362379); Figs. 5 – 6: Delray Beach, Palm Beach Co., E Florida (UF 470331); Figs. 7 – 10: off Looe Key, Florida Keys (UF 363833); Fig. 11: off Key Vaca, Marathon, Florida Keys (UF 470329); Figs. 12 – 15: Delray Beach, Palm Beach Co., E Florida (UF 470331); Figs. 16 – 18: paratypes, Delray Beach, Palm Beach Co., E Florida (UF 250571); Fig. 19: off Key Vaca, Marathon, Florida Keys (UF 470329); Figs. 20 – 22: paratypes, E of Pacific Reef Light, Miami-Dade Co., E Florida (USNM 900149); Figs. 23 – 25: SW of Key West, Florida Keys (USNM 900151); Figs. 26 – 28: paratypes, off Boynton Beach, Palm Beach Co., E Florida (UF 470330).