Talassia rugosa, Hoffman & Freiwald, 2022

Hoffman, Leon & Freiwald, André, 2022, A review of Atlantic deep-water species in the genus Talassia (Caenogastropoda, Vanikoridae), European Journal of Taxonomy 819, pp. 140-157 : 153-154

Talassia rugosa sp. nov.

urn:lsid:zoobank.org:act:F640609C-2447-4C82-9467-30AEC281163A

Figs 51–56

Etymology

The specific epithet refers to the rugose axial and spiral sculpture.

Type material

Holotype ANGOLA – Castle Mounds • 1 shell ( Figs 51–54 ); 9.6650° S, 12.7156° E; depth 453 m; 1 Jan. 2016; van Veen grab; in fine sand with clay; M122-GeoB20958 ; SMF358973 .

Paratypes ANGOLA – Castle Mounds • 1 shell ( Figs 55–56 ); same collection data as for holotype; SMF358974 • 2 shells; same collection data as for holotype; SMF358975 • 2 shells; same collection data as for holotype; Naturalis, Leiden, the Netherlands .

Description

Elevated shell with rounded whorls and flattened apex, irregular axial sculpture of raised ribs and spiral cordlets, flexuous lip and smooth protoconch, cream white. Holotype dimensions: height 3.2 mm, width 1.6 mm, apical angle 36°.

PROTOCONCH. Flattened paucispiral shell with 1¼ whorls ( Figs 52–53, 56 ); smooth; lip straight ( Fig. 56 ); width 0.34 mm.

TELEOCONCH. Elevated spire with 4 rounded whorls and deep suture ( Figs 51, 55 ). Axial sculpture with irregularly spaced slightly flexuous ribs and numerous growth lines. Irregularly-spaced spiral cordlets composed of sets of closely-aligned lines of various strength; lines composed of raised dots ( Fig. 54 ). Umbilicus nearly completely covered by columellar lip ( Fig. 51, 55 ).

APERTURE. Oval outline, slightly concave on parietal side; smooth inside ( Figs 51, 55 ). Columellar lip sharp; external lip not thickened, blunt, flexuous with notches above periphery and at base. Aperture height 1.1 mm in holotype.

VARIABILITY. Little variability observed. Observed adult height 3.0– 3.2 mm.

Distribution

The species is only known from the type locality.

Remarks

The radula and the soft parts of the new species are unknown.

Differential diagnosis

Talassia dagueneti has a similar teleoconch sculpture but its axial sculpture is more regular and lacks the spiral cordlets and its protoconch has a stronger spiral sculpture and a more elevated outline ( Warén & Bouchet 1988; Figs 4–7 ) whereas T. rugosa sp. nov. has a more conical outline, an irregular sculpture with spiral cordlets and a smooth protoconch with a flattened outline. Talassia mexicana sp. nov. from the Gulf of Mexico is larger and it has a more regular and stronger axial sculpture.

Figures

Figs 51–56. Talassia rugosa sp. nov., Angola, Castle Mounds, M122-GeoB20958. 51–54. Holotype (SMF358973). 51. Ventral view, H = 3.2 mm, W = 1.6 mm, Ha = 1.1 mm. 52–53. Protoconch, Wp = 0.34 mm. 54. Sculpture body whorl. 55–56. Paratype (SMF358974).55. Ventral view, H = 3.2 mm, W = 1.6 mm, Ha = 1.2 mm. 56. Protoconch, Wp = 0.34 mm, arrow indicates lip. Scale bars = 0.2 mm.

Figs 1–11. Talassia Warén & Bouchet, 1988 from the NE Atlantic. 1–3. Talassia coriacea (Manzoni, 1868), off Funchal, Madeira, depth 70 m (SaM74968). 1. Ventral view, H = 2.7, W = 1.5 mm, Ha = 1.2 mm. 2. Protoconch, Wp = 0.37 mm. 3. Sculpture body whorl. 4–7. Talassia dagueneti (de Folin, 1873), Porcupine Seabight, Galway Mound, POS316-524 (SaM). 4–5. Side view, H = 2.5 mm. 5. Protoconch, Wp = 0.32 mm. 6–7. Ventral view, H = 2.3 mm, W = 1.0 mm. 7. Sculpture body whorl. 8–11. Talassia tenuisculpta (R.B. Watson, 1873), Azores, Mar da Prata, M151-GeoB23111 (SaM). 8–10. Ventral view, H = 2.6 mm, W = 1.3 mm. 9–10. Protoconch, Wp 0.40 mm, arrow indicates lip. 11. Side view, H = 2.3 mm. Scale bars = 0.2 mm.