Bellardithala baluki, 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 : 19

Bellardithala baluki nov. sp.

Figs 7A 1 –A 2 , B 1 –B 2 , C 1 –C 2

Mitra Laubei nov. form.— Hoernes & Auinger, 1880: 89 (pars) [non Bellardithala laubei ( Hoernes & Auinger, 1880) ].

Type material. Holotype: NHMW 1859 /0047/0015, SL: 8.1 mm, MD: 2.7 mm, Vienna / Pötzleinsdorf ( Austria), figs 7A 1 –A 2 . Paratypes: NHMW 1859 /0047/0015a, SL: 8.5 mm, MD: 2.9 mm, Vienna / Pötzleinsdorf ( Austria), figs 7B 1 –B 2 ; NHMW 2020 /0063/0001, SL: 8.5 mm, MD: 2.9 mm, Vienna / Pötzleinsdorf ( Austria), figs 7C 1 –C 2 .

Type locality. Vienna / Pötzleinsdorf ( Austria) ,

Type stratum. Silty sand of the Baden Group.

Age. Middle Miocene, Badenian (Serravallian).

Etymology. In honour of Wacław Bałuk (University of Warsaw, Warszawa, Poland) in recognition of his contributions on Paratethyan gastropod systematics.

Diagnosis. Bellardithala species of medium size, moderately slender fusiform shell, with cyrtoconoid spire, and beaded sculpture differing from congeneric species by its slender bullet-like spire and delicate sculpture.

Description. Shell medium-sized, moderately slender fusiform with cyrtoconoid spire and narrowly incised suture. Protoconch unknown. Teleoconch of 4.5 weakly convex whorls, with periphery at abapical third of whorl, rapidly increasing in height. First teleoconch whorl with blunt axial ribs, crossed by six weak spiral threads, most prominent in axial interspaces. Regularly spaced axial ribs crossed by ten spiral cords on penultimate whorl, forming low beads at intersections. Last whorl weakly convex, with faint subsutural concavity, weakly constricted at base, bearing about 22 beaded spiral cords, adapical subsutural spiral cord most prominent, bearing prosocline nodes. Cords over fasciole prominent, where they develop as extensions of columellar folds. Aperture moderately narrow with shallow anal sinus. Columellar callus indistinct, poorly delimited. Columella with four prominent columellar folds. Outer lip weakly thickened; ten delicate denticles within. Siphonal canal moderately long, straight or bent slightly to left, with distinct siphonal notch.

Shell measurements and ratios. SL: 8.1–8.5 mm, MD: 2.7–2.9 mm, AA: 40–45°, SL/MD: 3.0–3.1, AL/AW: 4.6–5.2, AH/S: 2.1–2.2.

Discussion. Specimens of Bellardithala baluki nov. sp. were mixed with B. laubei by Hoernes & Auinger (1880). However, B. baluki nov. sp. differs from B. laubei ( Hoernes & Auinger, 1880) , as redefined herein, in its broader shell, beaded sculpture especially on the last whorl, and it develops only 4.5 teleoconch whorls instead of 5.5 in B. laubei . Bellardithala fedosovi nov. sp. is similar in shell shape, but differs in its smaller size, the more convex last whorl, the wider interspaces between the axial ribs, and the overall coarser sculpture. The type species, B. obsoleta ( Brocchi, 1814) from the Mediterranean Pliocene, differs in being slightly broader and the axial ribs are well developed and elevated. In B. baluki axial sculpture consists of axial rows of small beads, but do not form elevated ribs.

Distribution in Central Paratethys. Badenian (middle Miocene): Vienna /Pötzleinsdorf ( 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.