Lissodrillia vitrea, 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 : 258

Lissodrillia vitrea , new species

( Plate 131 )

Type material. Holotype 4.2 x 1.6 mm, T. Askew! (ANSP 372158); no paratypes.

Type locality. Off Freeport, Grand Bahama I., 26°31'00''N, 078°46'30''W, in 387 m.

Range and habitat. Known only from the holotype.

Description. Shell very small (4.2 mm), fusiform, glossy smooth, translucent; of about 6½ whorls total with slightly angular peripheries, the last about 56% of total shell length; sutures appressed. Sculpture consisting of ribs; aperture narrow, anterior canal moderately long. Protoconch of 1¾ smooth glossy whorls, the beginning of the first partially imbedded in the last ¾ whorl such that the protoconch appears dome-shaped. Axial sculpture of narrow opisthocline ribs, 12 on penultimate and 9 on last to varix, about as wide as their interspaces, obsolete on shoulder near suture, hooked from sulcus to periphery and extending obliquely to suture of succeeding whorl; to about ⅔ the distance to anterior canal on last whorl. Growth striae microscopic. Varix a thickened rib about ⅓-turn from edge of outer lip. Spiral sculpture absent. Sulcus band-like, narrow, flat not concave, below suture; without sculptural elements. Outer lip thin, without axial folds, smooth, edge forms an uninterrupted reversed “S” curve from suture to tip of anterior canal; stromboid notch not evident on type, which has a repaired outer lip. Anal sinus a deep notch on whorl shoulder adjacent to suture, its outer edge divergent, such that its edge is congruent with that of the outer lip. Inner lip thin, margined, extends over apex of aperture, callous at anal sinus weak. Anterior canal short but well defined, open, unnotched. Color translucent; ribs are an opaque white.

Remarks. Taxonomy. Lissodrillia vitrea has the characteristics of the genus: a very small glossy shell that lacks spiral sculpture, and with the inner edge of the anal sinus and edge of outer lip that trace a reverse “S”. Unlike most of its congeners, the sulcus is devoid of ribs, which are also quite oblique for the genus. Identification. At 4.2 mm this is among the smallest members of the genus. Lissodrillia verrillii (Dall, 1881) is a similar size but has more convex whorls. From Lissodrillia schroederi (Bartsch & Rehder, 1939) it differs in possessing more oblique ribs and a more translucent shell. From the same habitat and of a similar size but in a different genus, Syntomodrillia lissotropis (Dall, 1881) differs in possessing grooves in intercostal space and on the anterior canal. This single specimen merits description as a new species because it is morphologically different than its congeners (see Plate 132 ), and adds to the morphological diversity of the genus-group. An interesting observation is that four species, all from the Florida Straits, L. vitrea , L. verrillii (Dall, 1881) , Bellaspira minutissima , new species, and Syntomodrillia lissotropis (Dall, 1881) , are very small, plain, and similar in appearance, yet each retains the diagnostic characteristics of its genus.

Etymology. The Glassy Lissodrillia . The name refers to its translucent shell. From the Latin adjective vitreus, feminine vitrea , meaning resembling glass in its translucency.

Figures

PLATE 131. Lissodrillia vitrea, new species. Figs. 1 – 2: holotype (ANSP 372158), off Freeport, Grand Bahama I. Fig. 1: ventral, lateral, dorsal views; Fig. 2: apical view, V = varix, L = edge of outer lip.

PLATE 132. Lissodrillia spp. map and lineup. Fig. 1. Map of approximate known localities. Fig. 2. Holotype, 5.6 x 2.2 mm, L. arcas, new species (DMNH 46224). Fig. 3. Holotype, 5.4 x 2.1 mm, L. robusta, new species (ANSP 465241). Fig. 4. Lectotype, 5.6 x 2.2 mm, L. simpsoni (Dall, 1887) (USNM 61040). Fig. 5. Holotype, 5.0 x 2.0 mm, L. schroederi (Bartsch & Rehder, 1939) (USNM 530585). Fig. 6. Holotype, 6.2 x 2.8 mm, L. turgida, new species (UF 249933). Fig. 7. Non-type, 7.3 x 2.9 mm, L. ebur (Dall, 1927) (L. Campbell coll.). Fig. 8. Holotype, 6.8 x 2.8 mm, L. lactea, new species (UF 470328). Fig. 9. Holotype, 6.7 x 2.5 mm, L. levis, new species (UF 470338). Fig. 10. Holotype, 7.4 x 2.9 mm, L. cabofrioensis, new species (MZSP 122068). Fig. 11. Holotype, 7.2 x 2.6 mm, L. fasciata, new species (MZSP 122069). Fig. 12. Holotype, 4.2 x 1.6 mm, L. vitrea, new species (ANSP 372158). Fig. 13. Syntype, 4.4 mm, L. verrillii (Dall, 1881) (MCZ 7083).