Sinum magnificum, Harzhauser & Landau & Guzhov, 2025

Sinum magnificum nov. sp.

Figs 2T View FIGURE 2 , 59E–F View FIGURE 59 , 62A–D View FIGURE 62

Sigaretus haliotoideus Lk.— Hauer 1837: 420 View in CoL [ non Sinum haliotoideum ( Linnaeus, 1758) View in CoL ].

Sigaretus haliotoideus Lam.— Hörnes 1848: 22 View in CoL [ non Sinum haliotoideum ( Linnaeus, 1758) View in CoL ].

Sigaretus haliotoideus Linn.—Hörnes 1856: 513 View in CoL , pl. 46, fig. 27 [ non Sinum haliotoideum ( Linnaeus, 1758) View in CoL ].

S [ igaretus]. ( S [ igaretus].) striatus Serr.— Sieber 1958: 141 [ non Sinum striatus (de Serres, 1829) ].

Type material. Holotype, NHMW 1854 View Materials /0002/0072, SL: 23.0 mm, MD: 36.6 mm, Grund ( Austria), illustrated in Hörnes (1856: pl. 46, figs 27a–c), Figs 59E View FIGURE 59 , 62B View FIGURE 62 1 –B View FIGURE 1 4 View FIGURE 4 . Paratypes, NHMW 2024 View Materials /0239/0003, SL: 26.3 mm, MD: 31.5 mm, Grund ( Austria), Figs 59F View FIGURE 59 , 62C View FIGURE 62 1 –C View FIGURE 1 4 View FIGURE 4 . NHMW 2024 View Materials /0239/0005, SL: 23.3 mm, MD: 32.4 mm, Grund ( Austria), Figs 62A View FIGURE 62 1 –A View FIGURE 1 4 View FIGURE 4 . NHMW 1853 View Materials /0010/0033, SL: 22.1 mm, MD: 29.8 mm, Enzesfeld ( Austria), Figs 2T View FIGURE 2 , 62D View FIGURE 62 1 –D View FIGURE 1 4 View FIGURE 4 .

Additional material. NHMW 2024 View Materials /0239/0004 , SL: 18.2 mm, MD: 28.8 mm, Grund ( Austria) ; NHMW 2024 View Materials /0249/0001, 3 spec., Grund ( Austria); 15 spec. , NHMW 1855 View Materials /0002/0028, Grund ( Austria); 5 spec. , NHMW 2024 View Materials /0250/0001, Guntersdorf ( Austria) .

Type locality. Grund ( Austria), North Alpine-Carpathian Foreland Basin .

Type stratum. Silty sand of the Grund Formation.

Age. Middle Miocene, early Badenian (Langhian).

Etymology. Magnificum, Latin for magnificent.

Diagnosis. Medium sized, depressed auriculate shell with moderately depressed spire; protoconch of 1.5 whorls, sculpture of broad, flat spiral cords developing into bifid and trifid groups, base flattish, devoid of spiral sculpture.

Description. Medium sized, fragile, depressed shell of 2.75 auriculate teleoconch whorls (SL/MD = ~0.7–0.8). Protoconch broad turbiniform of 1.5 moderately convex whorls, diameter ~780 μm. Spire low conical; apical angle 130–135°. Suture linear, distinctly incised. Teleoconch whorls with very broad, weakly convex subsutural ramp, becoming weakly concave close to aperture. No shoulder angulation. Last whorl strongly expanding, attaining ~90–95% of total height. Periphery convex, far below mid-whorl (~39%). Growth lines distinct and prosocyrt in apical view, subobsolete at periphery. Sculpture of first teleoconch whorl of 15–16 broad, flat spiral cords separated by narrow grooves. Interspaces widening slightly on second teleoconch whorl, cords becoming bifid and trifid forming distinct groups. Spiral sculpture often blurred or wavy due to intersections with growth lines on last quarter of last whorl. Base flattish with prominent, opisthocyrt growth lines, devoid of spiral sculpture. Aperture wide, ovate, strongly prosocline. Position of adapical tip of aperture high (~85%), distinctly above mid-whorl. Aperture attaining ~80–85% of total height. Columellar lip forming moderately broad, rim, detached from base. Basal lip and outer lip thin. Columellar angle ~34–38°. Umbilicus reduced to narrow chink. Parietal callus short (~25%), forming thin callus sheet. No color pattern preserved.

Discussion. This is the largest Sinum species in the Paratethys Sea, known so far only by a few specimens. Sinum striatum (De Serres, 1829) , from the Pliocene of Italy, has a lower spire, is usually smaller and differs in its smaller protoconch (see Pedriali et al. 2019: fig. 33/8). Sinum striatum has simpler sculpture of broad spiral cords, which lack the deep splits of the cords of Sinum magnificum nov. sp. and its cords are not arranged in groups. Sinum patulum (Grateloup, 1847) (= Sinum aquense Récluz, 1851 ), from the Early Miocene of France, is smaller, has a higher shell and a larger protoconch (see Cossmann & Peyrot 1919: pl. 12, figs 47–48; Robba et al. 2016: pl. 15, figs 9–12).

Paleoenvironment. At the locality Grund fossiliferous channel fills, which formed in middle to outer neritic environments bear allochthonous assemblages uniting coastal-mudflat faunas with inner neritic ones ( Zuschin et al. 2005; Roetzel 2009). The preservation suggests an origin from sandy, inner neritic environments, which would also fit with the occurrence from Enzesfeld ( Austria).

Distribution in Central Paratethys. Badenian (Middle Miocene): North-Alpine-Carpathian Foreland Basin: Grund, Guntersdorf ( Austria) ( hoc opus); Vienna Basin: Enzesfeld ( Austria) ( hoc opus).