Talassia flexisculpta Hoffman & Freiwald 2022, sp. nov.

Talassia flexisculpta sp. nov.

urn:lsid:zoobank.org:act: E296DB40-9DC8-4EF4-A17B-B49046CAA209

Figs 44–50

Etymology

The specific epithet refers to the flexuous axial sculpture.

Type material

Holotype MAURITANIA – Arguin South 3 Canyon • 1 shell (Fig. 49); 19.7381° N, 17.1465° W; depth 483 m; 7 Nov. 2010; van Veen grab; in silty mud; MSM16/3-GeoB14858; SMF358970.

Paratypes MAURITANIA – Arguin South 3 Canyon • 2 shells (Figs 46–48, 50); same collection data as for holotype; SMF358971 • 1 shell same collection data as for holotype; SMF358972.

Other material examined

MAURITANIA • 1 shell; Tanôudêrt Canyon; 20.2429° N, 17.6681° W; depth 490 m; 3 Nov. 2010; box core in coral rubble with silty mud; MSM16/3-GeoB14799; SaM79754 • 1 shell (Figs 44–45); Timiris deep coral mound chain; 18.9634° N, 16.8688° W; depth 498 m; 11 Nov. 2010; box core in coral rubble with silty mud; MSM16/3-GeoB14877; SaM79756 • 1 shell; Banda Mounds; 17.6794° N, 16.6684° W; depth 450 m; 8 Jan. 2007; box core in coral rubble with mud; POS346-GeoB11579; SaM79753 • 3 shells; Banda Mounds; 17.6699° N, 16.6736° W; depth 505 m; 14 Nov. 2010; bottom grab in silty mud; MSM16/3-GeoB14898; SaM81473.

Description

Elevated shell with rounded whorls, regular axial sculpture of raised flexuous ribs, flexuous lip and smooth protoconch, cream white. Holotype dimensions: height 2.5 mm, width 1.2 mm, apical angle 38°.

PROTOCONCH. Elevated paucispiral shell with globular nucleus and 1¼ whorls (Figs 45, 47, 50); first whorl smooth, last ¼ whorl with weak broad spiral bands; lip straight, slightly thickened (Fig. 50); width 0.44 mm.

TELEOCONCH. Elevated spire with 3 rounded whorls and deep suture (Figs 44, 46, 49). Axial sculpture with regularly spaced flexuous ribs and numerous growth lines. Many regularly-spaced spiral lines composed of closely-aligned raised dots (Fig. 48 of paratype). Narrow, deep, elongated umbilicus at base body whorl partly covered by parietal lip (Figs 46, 49).

APERTURE. Oval outline, flattened on parietal side; smooth inside (Figs 44, 46, 49). Parietal and columellar lip sharp; external lip not thickened, blunt, flexuous with notches above periphery and at base. Aperture height 1.0 mm in holotype.

VARIABILITY. Sculpture of the teleoconch shows variability in strength of axial ribs. In a subadult shell (Fig. 44), the umbilical slit is nearly closed. Observed range of adult height 2.4–2.5 mm.

Distribution

NE Atlantic Ocean, Mauritania, latitude 17.6– 20.3° N, known depth range 450– 505 m.

Remarks

The radula and the soft parts of the new species are unknown; only empty shells were found in or near coral debris with silty or muddy sand. Talassia flexisculpta sp. nov. was found sympatrically with T. laevapex sp. nov.

Differential diagnosis

Talassia dagueneti has a similar teleoconch sculpture but its whorls are more inflated, its spire is more elevated with a smaller apical angle and its protoconch has a strong spiral sculpture (Warén & Bouchet 1988; Figs 4–6) whereas T. flexisculpta sp. nov. has a more conical outline (Fig. 48) and a largely smooth protoconch (Figs 45, 47, 50). Talassia mexicana sp. nov. also has a similar teleoconch sculpture and a smooth protoconch; however, this species is taller and it has fine spiral cordlets on the teleoconch (Figs 22, 25, 29–30) which are absent in T. flexisculpta sp. nov. A comparison with other known species is given under T. laevapex sp. nov.