Bellardithala 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 : 22-23

Bellardithala dacica nov. sp.

Figs 8A 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) ]. Turricula cf. Laubei R. Hoern. u. Auing.— Friedberg, 1938: 133, text-fig. 42.

? Thala laubei (Hoern. et Auing.) — Kókay, 1966: 61, pl. 9, fig. 4.

Type material. Holotype: NHMW 1854 /0035/0105, SL: 6.9 mm, MD: 2.4 mm, Lăpugiu de Sus ( Romania), figs 8A 1 –A 2 . Paratypes: NHMW 2020 /0061/0001, SL: 7.3 mm, MD: 2.4 mm, Lăpugiu de Sus ( Romania), figs 8B 1 –B 2 ; NHMW 2020 /0061/0002, SL: 6.9 mm, MD: 2.4 mm, Lăpugiu de Sus ( Romania), figs 8C 1 –C 2 .

Type locality. Lăpugiu de Sus ( Romania), Făget Basin .

Type stratum. Silt and clay of the Dej Formation.

Age. Middle Miocene, Badenian (Langhian).

Etymology. Referring to Dacia, a province of the Roman Empire, covering also the territory of the Transylvanian Basin.

Diagnosis. Bellardithala species of medium size, moderately slender fusiform shell, with faintly cyrtoconoid slightly gradate spire, differing from congeneric species by its sculpture, which changes from prominent axial ribs and spiral cords with distinct nodes on early teleoconch whorls to densely spaced, cancellate pattern, with blurred nodes on later spire whorls and last whorl.

Description. Shell medium-sized, slender fusiform with faintly cyrtoconoid and slightly gradate spire. Protoconch largely damaged; last two protoconch whorls suggesting high conical shape. Teleoconch of 4.5 weakly convex whorl, separated by impressed suture, with periphery shifting from abapical suture to mid-whorl during growth. First teleoconch whorl with axial ribs separated by interspaces of about same width, crossed by five close-set spiral cords, forming spirally elongated nodes at intersections with ribs, persisting into interspaces. Nodes on adapical spiral row most prominent. Axial ribs broader and less prominent on later teleoconch whorls. Five to six spiral cords on later spire whorls, forming cancellate pattern with axial ribs. Spiral cord at adapical suture broader than others, separated by wider and deeper spiral groove from next spiral cord. Last whorl high, weakly convex, slowly contracting, with up to 25 densely spaced spiral cords. Nodes on spiral cords somewhat blurred above periphery and largely reduced below. Aperture elongate, narrow to moderately narrow, with indistinct anal notch. Columellar callus narrow, indistinct. Columella with four prominent columellar folds, weakening only slightly abapically. Outer lip weakly thickened, with about 11 delicate denticles within. Siphonal canal moderately long, bent slightly to left, with shallow siphonal notch.

Shell measurements and ratios. SL: 6.9–7.3 mm, MD: 2.4 mm, AA: 35–40°, SL/MD: 2.8–3.1, AL/AW: 5.0– 5.5, AH/S: 2.1–2.3.

Discussion. The holotype of Bellardithala dacica nov. sp. was mixed with Mitra laubei ( Hoernes & Auinger, 1880) by those authors. Despite some superficial similarity due to the prominent subsutural spiral cord, the species are distinguished by the slender shape of B. laubei and the different sculpture of early spire whorls (broad axial ribs with subordinate spiral sculpture in B. laubei vs narrower axial ribs and prominent spiral cords in M. dacica ).

A specimen described by Kókay (1966) as Thala laubei from Herend ( Hungary) differs from B. laubei also in its broader shape. It is reminiscent of B. cf. dacica but differs in its higher number of axial ribs on the spire and the distinct subsutural spiral cord. This specimen might indicate a further undescribed species.

Distribution in Central Paratethys. Badenian (middle Miocene): Ukrainian Fore-Carpathian Basin: Żukowce (Zhukivtsi) ( Ukraine) ( Friedberg 1938); Făget Basin: Lăpugiu de Sus ( Romania).

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 8 A1–A2. Bellardithala dacica nov. sp., holotype, Lăpugiu de Sus (Romania), NHMW 1854/0035/0105. B1–B2. Bellardithala dacica nov. sp., paratype, Lăpugiu de Sus (Romania), NHMW 2020/0061/0001. C1–C2. Bellardithala dacica nov. sp., paratype, Lăpugiu de Sus (Romania), NHMW 2020/0061/0002. D1–D2. Bellardithala kostejana (Boettger, 1906), lectotype, Coşteiu de Sus (Romania), SMF 360340. E1–E2. Bellardithala kostejana (Boettger, 1906), Lăpugiu de Sus (Romania), NHMW 2020/0064/0001. F. Bellardithala kostejana (Boettger, 1906), Lăpugiu de Sus (Romania), NHMW 2020/0064/0002. G. Bellardithala sp., Devínska Nová Ves (Slovakia), Z23408-P2003/27.