Lissodrillia schroederi (Bartsch & Rehder, 1939)

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 : 250

Lissodrillia schroederi (Bartsch & Rehder, 1939)

( Plate 127 )

Cerodrillia (Lissodrillia) schroederi Bartsch & Rehder, 1939: 130 ; pl. 17, fig. 8: Powell (1966: 74 [list]); Williams (2005: 1532).

Cerodrillia schroederi Bartsch & Rehder, 1939 : Perry (1940: 165; pl. 38, fig. 262); Perry & Schwengel (1955: 182; pl. 38, fig. 262); Abbott (1974: 272, sp. 3024 [list]); Turgeon et al. (1988: 96 [list]).

Lissodrillia schroederi (Bartsch & Rehder, 1939) : Turgeon et al. (1998: 256 [list]).

Type material. Holotype 5.0 x 2.0 mm (USNM 530585).

Type locality. R/V Albatross Sta. 2410, off Charlotte Harbor, W Florida, in 28 fms [51 m].

Other material examined. An additional 25 specimens were examined: 1 spec., 4.7 x 1.9 mm, in 55 m, SW of Panama City, Bay Co., W Florida, J. Moore! (EFG 11826); 4 spec., 5.2 x 2.0, 5.0 x 1.9, 4.9 x 1.9 & 5.2 x 1.9 mm, in 73–91 m, SW of Egmont Key, Hillsborough Co., W Florida, D. Steger! 1975 (DMNH 107133); 5 spec., 4.7, 4.6, 5.5, 6.7 & 6.3 mm, SW of Johns Pass, Pinellas Co., W Florida, D. Steger! 1975 (DMNH 107816); 5 spec., 3.3 x 1.6, 4.9 x 1.9, 5.1 x 1.9, 5.3 x 1.9 & 5.0 x 1.9 mm, in 183–229 m, W of Cape San Blas, Gulf Co., W Florida, R. & D. Black! (USNM 900145); 2 spec., 5.3 x 1.9 & 5.3 x 1.9 mm, in 73 m, 153 km W of Egmont Key, Hillsborough Co., W Florida, J. Moore! aboard Cavalier, Aug 1968 (UF 470335); 2 spec., 1 measured: 5.0 x 1.9 mm, in 30 m, W of Egmont Key, Hillsborough Co., W Florida, J. Moore! (ANSP 336130); 2 spec., 5.6 x 2.0 & 5.7 x 2.0 mm, in 73– 91 mm, SW of Egmont Key, Hillsborough Co., W Florida, D. Steger! 1966 (ANSP 306359); 4 spec., the best 3: 5.4 x 2.2, 5.3 x 1.9 & 4.9 x 1.9 mm, in 165 m, 16 mi SE of Dry Tortugas, Florida Keys, USBF Sta. 20030 (USNM 411179).

Range and habitat. W Florida (Gulf Co.; Bay Co.; Pinellas Co.; Hillsborough Co.); Florida Keys (off Dry Tortugas in Gulf of Mexico). Reported from 30–229 m; most depths are> 50 m.

Description. Shell very small (to 6.7 mm in total length), smooth and glossy, fusiform, anterior truncated, with up to about 7 slightly convex whorls, the last about 55% of total shell length; sculpted with ribs whose peripheries are near the anterior suture such that whorls appear to be cinched, or to sag. Aperture short, oval, with a short and wide but distinctly formed anterior canal. Protoconch of 1¾–2 smooth, glossy, relatively large (for shell size) whorls, the first partially imbedded in the second such that the shell apex appears blunt. Axial sculpture of smooth, round-crested ribs that run from suture-to-suture on spire whorls, evanesce at the columella on shell base; 10–11 on penultimate and 6–8 on last whorl to varix. Ribs are about as wide as intercostal space, sigmoidal and only slightly reduced on whorl shoulder. Growth striae microscopic, oblique to ribs and recurved on shoulder. Varix an enlarged rib, up to twice the width of preceding rib and positioned ⅓–½ turn from edge of outer lip. Spiral sculpture absent. Sulcus absent; recurved ribs and striae on whorl shoulder mark past positions of the sulcus. Outer lip thin and smooth, translucent except for axial folds, usually one near the edge of the outer lip, the effect is a smooth dorsum of the last whorl smooth, without axial folds. Edge of lip, together with anal sinus, trace a reversed “S” from sinus to anterior canal; stromboid notch weak. Anal sinus a deep wide notch with a round apex near suture, outer side divergent from inner. Inner lip narrow, margined, free on anterior canal, recumbent on parietal wall, formed into an elongate callus at the posterior end of the aperture. Anterior canal short, open, unnotched; fasciole not swollen. Color white or pink; a wide central white band is most evident on pink specimens.

Remarks. Taxonomy. Lissodrillia schroederi is the type species of the genus, consequently, characteristics considered important at the level of genus are the model of the genus: a small glossy shell with ribs suture-to-suture on spire whorls, anal sulcus lacking; anal sinus a deep, wide notch, its outer side and edge of outer lip tracing a reversed “S” from the sinus to the anterior canal; and spiral sculpture lacking. Variability. The average total length of 24 specimens is 5.16 mm (3.3–6.7 mm), their average W/ L ratio 0.303. In addition to all-white forms, all-pink, or pink with white ribs or a white band occur. Identification. Lissodrillia schroederi is similar to L. simpsoni (Dall, 1887) , L. robusta , new species, L. lactea , new species, and L. levis , new species. Lissodrillia simpsoni has ribs that end before the anterior fasciole, whereas they continue to the fasciole in L. schroederi . Lissodrillia schroederi is white to pink in color, whereas L. simpsoni is a golden brown. There are also habitat differences— L. schroederi is found in deeper water. From L. robusta it differs in being slimmer in form, lacking the bulging ribs that characterize L. robusta . This latter species is also uniformly colored, lacking the broad central band and sometimes pink color of L. schroederi . From L. lactea it differs in possessing less convex whorls, usually more ribs that are narrower and more distinct (10–11 versus 6–10 on the penultimate whorl). From L. levis it differs in being somewhat smaller (5.16 versus 6.74 mm in average total length), in having more distinct, but narrower ribs, and colored differently, white or pink, not the pale amber of L. levis .

Figures

PLATE 127. Lissodrillia schroederi (Bartsch & Rehder, 1939). Upper panel. Figs. 1 – 3: holotype, off Charlotte Harbor, Charlotte Co., W Florida (USNM 530585). Fig. 1: ventral, lateral & dorsal views; Fig. 2: protoconch (not to scale); Fig. 3: apical view, V = varix, L = edge of outer lip. Lower Panel, specimens from different localities, all W Florida. Figs. 4 – 7: SW of Egmont Key, Hillsborough Co. (DMNH 107133); Figs. 8 – 9: SW of Egmont Key, Hillsborough Co. (ANSP 306359); Fig. 10: off Egmont Key, Hillsborough Co. (ANSP 336130); Figs. 11 – 12: W of Egmont Key, Hillsborough Co. (UF 470335); Figs. 13 – 15: SW of Johns Pass, Pinellas Co. (DMNH 107816); Figs. 16 – 20: W of Cape San Blas, Gulf Co. (USNM 900145).