Bellardithala kovaci, 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 : 18-19

Bellardithala kovaci nov. sp.

Figs 4C , 6D 1 –D 2 , E 1 –E 2 , F 1 –F 2 , G 1 –G 2 , H 1 –H 2 , I 1 –I 2

[ Mitra ] candidula [Partsch]— Hörnes 1848: 17 [nomen nudum].

Mitra obsoleta Bronn [sic]— Hörnes 1852b: 110, pl. 10, figs 32a–b [non Voluta obsoleta Brocchi, 1814 ].

[ Mitra ] obsoleta Brocc. — Auinger 1871: 8 [non Brocchi, 1814].

[ Callithea ] obsoleta Brocc. —Hoernes 1880: 125 [non Brocchi, 1814].

Mitra obsoleta Brocc. — Hoernes & Auinger 1880: 88 [non Brocchi, 1814].

Mitra obsoleta Braun. — Rzehak 1894: 256 [non Brocchi, 1814].

Thala obsoleta Brocch. — Meznerics 1933: 344 [non Brocchi, 1814].

Vexillum (Costellaria) obsoletum (Brocc.) — Sieber 1956: 244 [non Brocchi, 1814].

Th [ala]. obsoleta (Brocchi) — Sieber 1958a: 153 [non Brocchi, 1814].

Thala obsoleta (Brocc.) — Sieber 1958b: 149 [non Brocchi, 1814].

Thala obsoleta ( Brocchi, 1814) — Bałuk 1997: 39, pl. 11, fig. 2 [non Brocchi, 1814].

Type material. Holotype: NHMW 1846 /0037/0114, SL: 8.3 mm, MD: 3.1 mm, Steinebrunn ( Austria), illustrated in Hörnes (1852b, pl. 10, figs 32a–b), figs 6D 1 –D 2 . Paratypes: NHMW 1858 /0047/0007, SL: 8.9 mm, MD: 3.3 mm, Sedlec (= Porzteich) ( Czech Republic), figs 6E 1 –E 2 ; NHMW 1866 /0001/1019, SL: 6.8 mm, MD: 2.7 mm, Forchtenau ( Austria), figs 6F 1 –F 2 ; NHMW 1871 /0010/0331, SL: 6.0 mm, MD: 2.2 mm, Steinebrunn ( Austria), figs 4C, 6G 1 –G 2 ; NHMW 1871 /0011/0004, SL: 5.9 mm, MD: 2.2 mm, Steinebrunn ( Austria), figs 6H 1 –H 2 .

Additional material. NHMW 2020 /0062/0001, SL: 5.7 mm, MD: 2.1 mm, Steinebrunn ( Austria), figs 6I 1 –I 2. 18 specimens NHMW 2020 /0062/0002, all Steinebrunn ( Austria) .

Type locality. Steinebrunn ( Austria) .

Type stratum. Silty sand of the Baden Formation.

Age. Middle Miocene, Badenian (Langhian).

Etymology. In honour of Michal Kováč (Comenius University, Bratislava, Slovakia), in recognition of his contributions on the stratigraphy and paleogeography of the Paratethys Sea.

Diagnosis. Medium-sized, moderately slender fusiform shell differing from other Bellardithala species by its weak spiral sculpture and broad flat axial ribs separated by very narrow interspaces.

Description. Shell medium-sized, moderately slender fusiform with slightly cyrtoconoid spire. Protoconch (fig. 4C) high conical of 3.5 weakly convex whorls; height: 660 μm, diameter: 580 μm. Teleoconch of moderately convex 5.5 whorls with periphery slightly below mid-whorl; suture narrowly incised. Last whorl high, weakly convex with weak basal constriction. Sculpture of first teleoconch whorl of broad, slightly opisthocline axial ribs with flattened tops separated by narrow interspaces. Spiral sculpture reduced to five spiral threads in axial interspaces. Axial ribs becoming broad and low on later spire whorls with irregularly spaced narrow interspaces. Spiral threads restricted to axial interspaces causing tiny pits between axial and spiral elements. Interspaces very narrow, present throughout growth. Spiral grooves somewhat stronger in adapical third of last whorl causing tiny pits at intersections with axial interspaces. Axial sculpture weakening towards fasciole. Aperture elongate, moderately narrow with distinct, narrow anal sinus. Inner lip narrow, indistinct. Columella with four broad folds, adapical two most prominent. Outer lip thickened with 10 denticles on inner side. Siphonal canal moderately short, moderately wide, straight with shallow siphonal notch.

Shell measurements and ratios. NHMW specimens: SL: 6.8–8.5 mm, MD: 2.7–3.3 mm; AA: 44–46°, SL/ MD: 2.8, AL/AW: 4.7–5.3, AH/S: 2.4–2.6.

Remarks. Bellardithala kovaci is documented also by subadult specimens (figs 6G 1 –G 2, H 1 –H 2) illustrating the development of denticles in juveniles, which was also observed in B. partschi by Rosenberg & Salisbury (2003).

This species was misidentified so far as Bellardithala obsoleta ( Brocchi, 1814) , which was originally described from the Italian Pliocene. The holotype of Voluta obsoleta Brocchi, 1814 , illustrated in Rossi Ronchetti (1955) and Pinna & Spezia (1978), differs clearly from the Paratethyan species in having prominent axial sculpture, on spire whorls and last whorl. Pliocene specimens of B. obsoleta from Altavilla ( Italy), described by Giannuzzi-Savelli & Reina (1983), differ from the Paratethyan species also in the more prominent axial and spiral sculpture and have a more slender fusiform outline. Serravallian specimens from the Karaman Basin in Turkey, described by Landau et al. (2013) as Thala obsoleta , differ from the Paratethyan species clearly in the prominent axial ribs and the subcylindrical spire whorls. The same features distinguish Tortonian specimens from Montegibbio in Italy from Bellardithala kovaci (see Davoli, 2000). Bellardithala boehmi ( Boettger, 1906) differs in its more slender fusiform outline, much more prominent axial and spiral sculpture on the early teleoconch whorls, and the lower aperture/spire ratio (0.9 versus 1.1).

Palaeoenvironment. Coastal, inner neritic. The assemblage from Steinebrunn suggests shallow sublittoral environments with sea grass ( Harzhauser & Landau 2019).At the Niederleis section, sediment and fossils from coastal and lagoonal environments not exceeding 30 m water depth were transported by tempestites into offshore settings ( Mandic et al. 2002).

Distribution in Central Paratethys. Badenian (middle Miocene): North Alpine-Carpathian Foreland Basin: Unkovice ( Czech Republic) ( Rzehak 1894); Korytnica Basin: Korytnica ( Poland) ( Bałuk 1997); Vienna Basin: Niederleis, Steinebrunn ( Austria); Mikulov, Sedlec (= Porzteich) ( Czech Republic) ( Hoernes & Auinger 1880); Eisenstadt-Sopron Basin: Forchtenau ( Austria) ( Sieber 1956).

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 4. Protoconchs of Paratethyan Costellariidae. A. Antithala filipescui nov. sp., Lăpugiu de Sus (Romania), NHMW 1876/0011/0012). B. Antithala sturi (Hoernes & Auinger, 1880), Lăpugiu de Sus (Romania), NHMW 2020/0058/0001. C. Bellardithala kovaci nov. sp., Steinebrunn (Austria), NHMW 2020/0062/0001. D. Bellardithala partschi (Hörnes, 1852), Steinebrunn (Austria), NHMW 2020/0060/0003. E. Ebenomitra leucozona (Andrzejowski, 1830), Lăpugiu de Sus (Romania), NHMW 1876/0011/0008. F. Ebenomitra pseudopyramidella (Boettger, 1906), Steinebrunn (Austria), NHMW 1857/0014/0009. G. Fedosovia fuchsi (Hoernes & Auinger, 1880), lectotype, Lăpugiu de Sus (Romania), NHMW 1857/0024/0012. H. Pusia avellanella (Boettger, 1906), Gainfarn (Austria), NHMW 2020/0072/0001. I. Pusia? confunda nov. sp., holotype, Coşteiu de Sus (Romania), SMF 360341. J. Pusia pseudorecticosta (Boettger, 1906), Pusia pseudorecticosta (Boettger, 1906), Steinebrunn (Austria), NHMW 2020/0076/0005. K. Pusia schafferi (Meznerics, 1933), Steinebrunn (Austria), NHMW 2020/0078/0002. L. Pusia vexans (Boettger, 1902), Coşteiu de Sus (Romania), NHMW 2020/0081/0001. M. Vexillum intermittens (Hoernes & Auinger, 1880), paralectotype, Baden or Bad Vöslau (Austria), NHMW 2020/0087/0003. N. Vexillum michelottii (Hörnes, 1852), lectotype, Baden (Austria), NHMW 1851/0013/0001. O. Tosapusia pseudocupressina Bałuk, 1997, Lăpugiu de Sus (Romania), NHMW 1870/0033/0037.

FIGURE 6. A1–A2. Bellardithala boehmi (Boettger, 1906), lectotype, Coşteiu de Sus (Romania), SMF 360342. B1–B2. Bellardithala boehmi (Boettger, 1906), Lăpugiu de Sus (Romania), NHMW 2020/0059/0001. C1–C2. Bellardithala boehmi (Boettger, 1906), Lăpugiu de Sus (Romania), NHMW 1854/0035/0107. D1–D2. Bellardithala kovaci nov. sp., holotype, Steinebrunn (Austria), NHMW 1846/0037/0114. E1–E2. Bellardithala kovaci nov. sp., paratype, Sedlec (= Porzteich) (Czech Republic), NHMW 1858/0047/0007. F1–F2. Bellardithala kovaci nov. sp., paratype, Forchtenau (Austria), NHMW 1866/0001/1019. G1–G2. Bellardithala kovaci nov. sp., paratype, Steinebrunn (Austria), NHMW 1871/0010/0331. H1–H2. Bellardithala kovaci nov. sp., paratype, Steinebrunn (Austria), NHMW 1871/0011/0004. I1–I2. Bellardithala kovaci nov. sp., Steinebrunn (Austria), NHMW 2020/0062/0001.