Syntomodrillia stahlschmidti, 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 : 344-346

Syntomodrillia stahlschmidti , new species

( Plate 179 )

Type material. Holotype 8.9 x 3.2 mm, (SMF 336443); 5 paratypes, all from the type locality: 8.4 x 3.1 mm (author’s coll.), 8.5 x 3.1, 8.2 x 3.0, 7.7 x 2.8 mm (P. Stahlschmidt coll.), & 7.3 x 2.7 mm (MNHN-IM-2000- 30464).

Type locality. Bahia Concha, Magdalena Dept., Colombia, in 20– 30 m. Range and habitat. Known only from the type locality.

Description. Shell very small (to 8.9 mm in total length), narrowly fusiform, glossy, translucent; up to 9¼ whorls, flat to slightly convex, sculptured with ribs, with impressed sutures and perimeters below mid-whorl, the last approximately 58% of total shell length; aperture narrowly oval; anterior canal moderately long. Protoconch of 2½ round, translucent, symmetrically expanding whorls; tip of first partially immersed in second such that the spire tip appears blunt. The translucent protoconch whorls appear to be filled with a granular material, perhaps small sand grains. Axial sculpture of broad arcuate ribs that run suture-to-suture on spire whorls and to anterior fasciole on last; ribs slightly recurved on shoulders, wider than intercostal space, with ridged crests. First teleoconch whorl with 8–9 narrow ribs that are more convex than on subsequent whorls, 9–10 on penultimate, and 8–10 on last whorl to varix. Varix convex, higher and wider than adjacent ribs, straight, positioned about ⅓-turn from edge of outer lip. Spiral sculpture of faint spiral grooves on at least last two whorls, obsolete on rib crests and absent in sulcus. Threads number about 9 on anterior fasciole, sharply set off from spiral grooves in intercostal space. Sulcus barely evident, indicated by the absence of intercostal grooves, which are present elsewhere on the whorl, and slightly recurved ribs and growth striae. Outer lip flattened, with 3 or more weak to strong axial folds; edge of lip from anal sinus to anterior canal forms an arc indented at stromboid notch and bent to join with the anterior canal. Anal sinus a deep notch with a round apex adjacent to suture; sides slightly divergent. Inner lip narrow, erect anteriorly, thinnest on parietal wall, and developed into a weak callus posteriorly, where it joins the outer lip. Anterior canal moderately long, open, turned to the right when viewed ventrally, notched asymmetrically; columella straight; fasciole not swollen. Color a light golden brown base with a broad, white spiral band that lacks distinct boundaries, positioned above the suture line.

Remarks. Taxonomy. Syntomodrillia stahlschmidti has the principal characteristics of Syntomodrillia : a small, slender, glossy shell, moderately long anterior canal, axial ribs that extend from suture-to-suture, microscopic intercostal grooves, and a narrow, not hump-like, varix removed from the edge of the lip by ⅓-turn. Variability. The six specimens have an average total length of 8.17 mm (7.3–8.9 mm) and an average W/ L ratio of 0.365. The cream-white specimen seems to be a rarer color variant, normal being a light golden brown. Identification. Syntomodrillia stahlschmidti is similar to S. hesperia , new species, S. peggywilliamsae , new species, S. portoricana , new name, and S. trinidadensis , new species. From S. hesperia it can be distinguished by its 2½-whorl protoconch (not 1½ whorls as in S. hesperia ), and clearer spiral white band. From S. peggywilliamsae it can also be distinguished by the number of protoconch whorls (2½ versus 2) and by its much more distinct white spiral band. From S. trinidadensis it differs in being smaller and slimmer, and in possessing a protoconch with more whorls (2½ versus 1¾). From S. portoricana it differs in possessing a straighter anterior canal, a less globose protoconch, and a white spiral band. It lacks the dark color patch that is present on the varix of S. portoricana .

Etymology. Stahlschmidt’s Syntomodrillia ; named in honor of Dr. Peter Stahlschmidt for having provided all of the material for this description, and for his dedication to molluscan taxonomy.

Figures

PLATE 179. Syntomodrillia stahlschmidti, new species. Upper panel. Figs. 1 – 3: holotype, Bahia Concha, Magdalena Dept., Colombia (SMF 336443). Fig. 1: ventral, lateral, and dorsal views; Fig. 2: enlarged view of protoconch (not to scale); Fig. 3: apical view, V = varix, L = edge of outer lip. Lower panel. Figs. 4 – 8: paratypes from the type locality Figs. 4, 6 – 7: P. Stahlschmidt coll.; Fig. 5: author’s coll.; Fig. 8: MNHN IM- 2000 - 30464.