Bellardithala fedosovi, 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 : 20

Bellardithala fedosovi nov. sp.

Figs 7D 1 –D 2 , E 1 –E 2

Mitra Lapugyensis nov. form.— Hoernes & Auinger 1880 (pars): 89, pl. 10, figs 22 [non Bellardithala lapugyensis ( Hoernes & Auinger 1880) ].

Th [ala]. lapugyensis (R. Hörn, et Au.)— Sieber 1958a: 153 [non Bellardithala lapugyensis ( Hoernes & Auinger 1880) ].

Thala lapugyensis (R. Hörn. Auing.) — Sieber 1958b: 149 [non Bellardithala lapugyensis ( Hoernes & Auinger 1880) ].

Type material. Holotype: NHMW 1864 /0001/0563, SL: 7.5 mm, MD: 2.8 mm, Steinebrunn ( Austria), illustrated in Hoernes & Auinger (1880, pl. 10, fig. 22a–c), figs 7D 1 –D 2 . Paratype: NHMW 2020 /0052/0001, SL: 7.1 mm, MD: 2.7 mm, Steinebrunn ( Austria), figs 7E 1 –E 2 .

Type locality. Steinebrunn ( Austria) .

Type stratum. Silty sand of the Baden Formation.

Age. Middle Miocene, Badenian (Langhian).

Etymology. In honour of Alexander Fedosov (Russian Academy of Sciences, Moscow), in recognition of his contributions on the molecular phylogeny of Costellariidae and Mitridae .

Diagnosis. Bellardithala species of medium size, moderately slender fusiform shell, with weakly cyrtoconoid spire, slowly contracting last whorl, beaded axial ribs, distinguished from congeneric species by the high number of spiral cords on the penultimate and last whorls, and the bifid subsutural spiral cord.

Description. Shell medium-sized, moderately slender fusiform with weakly cyrtoconoid spire and narrowly incised suture. Protoconch unknown. Teleoconch of 4.5 weakly convex whorls, with periphery in abapical third. Axial sculpture on first teleoconch whorl consisting of about ten prominent, orthocline to weakly opisthocline axial ribs, separated by narrower interspaces, crossed by five spiral cords. Spiral cords forming weak, rectangular nodes at intersections with ribs and narrow grooved in interspaces. Later teleoconch whorls with densely spaced axial ribs, crossed by seven to eight spiral cords resulting in somewhat blurred beads. Prominent, nodular bifid subsutural spiral cord, separated from following cord by deeper spiral groove, especially on last whorl; secondary nodular spiral cord intercalated in this groove in some specimens. Last whorl weakly convex with weakly constricted base, bearing about 15 beaded spiral cords, arranged in narrowly sigmoidal axial ribs. Fasciole weak, bearing weak spiral cords. Aperture elongate, moderately narrow, with indistinct anal sinus. Columellar callus narrow. Columella with four columellar folds, weakening abapically. Outer lip only weakly thickened, with about eight delicate denticles within. Siphonal canal wide, moderately long, straight, with shallow siphonal notch.

Shell measurements and ratios. SL: 7.1–7.5 mm, MD: 2.3–2.7 mm, AA: 45–49°, SL/MD: 2.7–2.9, AL/AW: 3.7–4.4, AH/S: 2.3–2.4.

Discussion. The holotype of Bellardithala fedosovi nov. sp. was mixed up with Bellardithala lapugyensis ( Hoernes & Auinger, 1880) by those authors, but is readily distinguished from that species by its tubercular sculpture (compared to the cancellate sculpture of B. lapugyensis ), and the greater number of spiral cords on the penultimate and last whorls. Bellardithala partschi (Hörnes, 1852) is somewhat similar, but also has fewer spiral cords, and the spire is less cyrtoconoid. Bellardithala baluki nov. sp. differs in having finer sculpture composed of more numerous axial rows of smaller beads rather than tubercles separated by narrower interspaces. As with the previous species, the type species B. obsoleta ( Brocchi, 1814) differs in having more strongly developed and elevated axial ribs that are less strongly tubercular, separated by deeper interspaces.

Palaeoenvironment. The Niederleis section exposed sediment and fossils from coastal and lagoonal environments not exceeding 30 m water depth, which were transported by tempestites into offshore settings ( Mandic et al. 2002).

Distribution in Central Paratethys. Badenian (middle Miocene): Vienna Basin: Niederleis ( Austria).

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.