Bellardithala baluki Harzhauser & Landau 2021, nov. sp.
Creators: name: Harzhauser, Mathias
name: Landau, Bernard
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Neogastropoda
Costellariidae
Bellardithala
Bellardithala baluki

description: 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).
description: Published as part of Harzhauser, Mathias & Landau, Bernard, 2021, An overlooked diversity-the Costellariidae (Gastropoda: Neogastropoda) of the Miocene Paratethys Sea, pp. 1-70 in Zootaxa 4982 (1) on page 19, DOI: 10.11646/zootaxa.4982.1.1, http://zenodo.org/record/4921842