Syntomodrillia peggywilliamsae, 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 : 339-340

Syntomodrillia peggywilliamsae , new species

( Plate 175 )

Type material. Holotype 8.2 x 3.0 mm, G. Macintosh! 25 Sep 1997, ex P. Williams coll. (USNM 1291380). Type locality. Store Bay, Tobago I., Trinidad & Tobago, in 23 m.

Range and habitat. Known only from the holotype.

Description. Shell very small (8.2 mm in total length), narrowly fusiform, glossy, with numerous ribs and a moderately long anterior canal. Whorls 8¾, slightly convex with perimeters below mid-whorl, the last whorl approximately 57% of total shell length; sutures impressed. Protoconch of 2 round, translucent, expanding whorls; tip of first slightly impressed in second. Axial sculpture of ribs that run suture-to-suture on spire whorls and to anterior fasciole on last; ribs slightly opisthocline on spire whorls, and narrower and recurved on the shoulder. First teleoconch whorl with 9 narrow ribs, more convex than those on subsequent whorls; ribs 9 on penultimate, and 7 on last whorl to varix. Ribs wider than intercostal space; crests ridged. Growth striae present, fainter than spiral grooves. Varix strongly convex, higher and wider than adjacent ribs but aligned straight, not inclined, and positioned about ¼-turn from edge of outer lip; slightly recurved on shoulder. Spiral sculpture of faint, barely perceptible spiral grooves on the last 3 teleoconch whorls, obsolete on rib crests and absent on shoulder near suture. Threads and ridges develop on anterior portion of base and are strongest on anterior fasciole. Sulcus absent; past positions of anal sinus indicated by the absence of intercostal grooves and slightly recurved ribs and growth striae. Outer lip flattened, with one strengthening axial fold on the regenerated outer lip of the type; edge of lip from anal sinus to anterior canal forms a low arc indented at stromboid notch. Anal sinus a deep notch with a round apex; sides slightly divergent; entire sinus directed laterally, spout-like. Inner lip erect anteriorly, recumbent on parietal wall, and detached and directed laterally along parietal side of anal sinus. Parietal callus weak. Anterior canal moderately long, open, turned slightly to the right at its end when viewed ventrally, notched asymmetrically; columella straight; fasciole with 9 spiral ridges. Color a light golden brown, with a broad, faint, white spiral band about mid-whorl.

Remarks. Taxonomy. Syntomodrillia peggywilliamsae has all of the principal characteristics of Syntomodrillia : a small, slender, glossy shell, moderately long anterior canal, axial ribs that extend from suture-tosuture, microscopic intercostal grooves, and a narrow, not hump-like, varix removed from the edge of the lip by ¼- to ⅓-turn. Identification. Syntomodrillia peggywilliamsae is very similar to S. hesperia , new species, S. trinidadensis , new species, and S. stahlschmidti , new species. It has more protoconch whorls than S. hesperia (2 versus 1½) and S. trinidadensis (2 versus 1¾), but fewer than S. stahlschmidti (2 versus 2½), and its central white band is more obscure than that of S. stahlschmidti . From S. trinidadensis it differs in being smaller and slimmer, and in possessing a protoconch with more whorls (2 versus 1¾). These four species are very similar in their gross morphology and probably stem from a common ancestor. However, protoconch whorl numbers suggest that speciation has occurred, which is possible given their geographic isolation on widely separated island localities.

Etymology. Peggy Williams’ Syntomodrillia . Named in honor of Mrs. Peggy Williams for having contributed the specimen here described, and for her devotion to the collection and study of turrid families.

Figures

PLATE 175. Syntomodrillia peggywilliamsae, new species. Figs. 1 – 3: holotype, Store Bay, Tobago I., Trinidad & Tobago, ex P. Williams coll. (USNM 1291380). 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.