Bellardithala cf. dacica, Harzhauser & Landau, 2021

Harzhauser, Mathias & Landau, Bernard, 2021, An overlooked diversity-the Costellariidae (Gastropoda: Neogastropoda) of the Miocene Paratethys Sea, Zootaxa 4982 (1), pp. 1-70 : 24

Bellardithala cf. dacica nov. sp.

Figs 7G 1 –G 2 , H 1 –H 2 , I 1 –I 2

Mitra Laubei nov. form.— Hoernes & Auinger 1880: 89 (pars), pl. 10, figs 20a–c) [non Bellardithala laubei ( Hoernes & Auinger 1880) ].

Material. NHMW 1866/0001/0806, SL: 7.5 mm, MD: 2.6 mm, Niederleis ( Austria), illustrated in Hoernes & Auinger (1880, pl. 10, figs 20a–c), figs 7G 1 –G 2; NHMW 2020/0054/0001, SL: 6.7 mm, MD: 2.6 mm, Niederleis ( Austria), figs 7H 1 –H 2; NHMW 2020/0054/0002, SL: 7.1 mm, MD: 2.4 mm, Niederleis ( Austria), figs 7I 1 –I 2.

Description. Shell medium-sized, moderately slender fusiform, with weakly gradate spire. Protoconch unknown. Teleoconch of 4.5 weakly convex to subcylindrical whorls. Axial sculpture of orthocline, regularly spaced axial ribs on first teleoconch whorl, separated by narrower interspaces. Spiral sculpture consisting of four narrow spiral cords on first whorl, increasing in number to up to nine cords on last spire whorl. Spiral cords most prominent in axial interspaces, forming indistinct nodes at intersections with axial ribs. Axial ribs predominate sculpture on spire whorls and weaken on last whorl. Axial and spiral sculpture resulting in densely spaced pattern of blurred nodes. Last whorl subcylindrical above periphery, slowly contracting below. Spiral cords more prominent on base, weak fasciole. Aperture elongate, moderately narrow with indistinct anal sinus. Columella with four prominent folds. Outer lip thickened, with about 11 distinct denticles within; ten narrow lirae close behind peristome, distinctly separated from denticles. Siphonal canal moderately long, straight with shallow siphonal notch.

Shell measurements and ratios. SL: 6.7–7.5 mm, MD: 2.4–2.6 mm, AA: 35–39°, SL/MD: 2.9–3.0, AL/AW: 4.5–5.2, AH/S: 2.1–2.2.

Discussion. Some specimens from the Vienna and Pannonian basins differ slightly from Bellardithala dacica nov. sp. in having inner lirae or denticles present in all specimens seen, whereas they are not present in the specimen of B. laubei ( Hoernes & Auinger, 1880) at hand, nor in specimen of B. dacica nov. sp. However, in other congeners, these inner teeth or lirae are only seen in a small proportion of specimens, and therefore we hesitate to use their presence/absence as a species-specific character. Sculpture is similar to that of B. dacica , possibly on the stronger end of the range of variability, but again insufficiently consistent to separate the two. Although probably just a local variety, we leave these specimens in open nomenclature, and highlight the similarity and differences with typical B. dacica .

Distribution in Central Paratethys. Badenian (middle Miocene): Vienna Basin: Niederleis ( Austria);? Pannonian Basin: Herend ( Hungary).

Figures

FIGURE 1. A. Map of central and southeastern Europe, representing the area that was partly covered by the Central Paratethys Sea (for detailed maps with the localities mentioned in the text see Kroh (2005) and Nosowska (2020). The white insert corresponds to the area that is restored in the palaeogeographic map below. B. Paleogeography of the Middle Miocene Paratethys Sea (modified from Harzhauser et al. 2007) showing the most important sedimentary basins (NAFB: North Alpine Foreland Basin, E–Sopr B: Eisenstadt–Sopron Basin).

FIGURE 2. Measurements to shell morphology and whorl profiles. SL: shell length, MD: maximum diameter, AA: apical angle, LWH: last whorl height, AH: aperture height. AL: aperture length. AW: aperture width. S: length of siphonal canal.

FIGURE 7 A1–A2. Bellardithala baluki nov. sp., holotype, Vienna/Pötzleinsdorf (Austria), NHMW 1859/0047/0015. B1–B2. Bellardithala baluki nov. sp., paratype, Vienna/Pötzleinsdorf (Austria), NHMW 1859/0047/0015b. C1–C2. Bellardithala baluki nov. sp., paratype, Vienna/Pötzleinsdorf (Austria), NHMW 2020/0063/0001. D1–D2. Bellardithala fedosovi nov. sp., holotype, Steinebrunn (Austria), NHMW 1864/0001/0563. E1–E2. Bellardithala fedosovi nov. sp., paratype, Steinebrunn (Austria), NHMW 2020/0052/0001. F1–F2. Bellardithala laubei (Hoernes & Auinger, 1880), lectotype, Bad Vöslau (Austria), NHMW 1999z0076/0002. G1–G2. Bellardithala cf. dacica nov. sp., Niederleis (Austria), NHMW 1866/0001/0806. H1–H2. Bellardithala cf. dacica nov. sp., Niederleis (Austria), NHMW 2020/0054/0001. I1–I2. Bellardithala cf. dacica nov. sp., Niederleis (Austria), NHMW 2020/0054/0002.