Solatisonax tavianii Harzhauser & Landau 2023, nov. sp.
Creators: name: Harzhauser, Mathias
name: Landau, Bernard
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Heterostropha
Architectonicidae
Solatisonax
Solatisonax tavianii

description: Solatisonax tavianii nov. sp.
Figs 4I, 10A–D
Type material. Holotype: NHMW 2016 /0177/0038a, SL: 7.0 mm, MD: 14.7 mm, Lăpugiu de Sus (Romania), Figs 10C 1 –C 2. Paratype: NHMW 2016 /0177/0038b, SL: 5.1 mm, MD: 12.2 mm, Lăpugiu de Sus (Romania), Figs 10D 1 –D 2. NHMW 2016 /0266/0001, SL: 7.5 mm, MD: 13.7 mm, Lăpugiu des Sus (Romania), Figs 10A 1 – A 2. NHMW2016 /0266/0002, SL: 8.0 mm, MD: 15.0 mm, Lăpugiu des Sus (Romania) Figs 4I, 10B 1 –B 2. NHMW 2016 /0266/0003, SL: 5.5 mm, MD: 12.5 mm, Lăpugiu des Sus (Romania). NHMW 2016 /0266/0004, SL: 7.9 mm, MD: 14.9 mm, Lăpugiu des Sus (Romania). NHMW 1854 /0035/0332, SL: 4.7 mm, MD: 10.5 mm, Lăpugiu des Sus (Romania); 1 spec., NHMW 2016 /0177/0337, Lăpugiu des Sus (Romania).
Type locality. Lăpugiu de Sus (Romania).
Type stratum. Silt and clay of the Dej Formation.
Age. Middle Miocene, early/middle Badenian (Langhian).
Etymology. In honor of Marco Taviani (National Research Council, Bologna, Italy) in recognition of his contributions in Mediterranean paleontology.
Diagnosis. Medium-sized, depressed lentiform shell with low conical spire with reduced spiral sculpture on dorsal side and short axial ribs along subsutural cord. UC indistinct, poorly delimited from basal field. Umbilicus moderately wide, narrowly funnel-shaped.
Description. Medium-sized, depressed lentiform shell with low conical spire and angulated periphery. Protoconch heterostrophic, medium-sized of 1.2 visible whorls (diameter 1.2 mm). Teleoconch of about 4.2 whorls. Early teleoconch whorls weakly convex. SSC and MCs indistinct. UPC and LPC finely beaded. SSC of later whorls represented by row of short, somewhat drop-shaped axial ribs, followed by about three poorly defined, beaded spiral threads, intercalated by even weaker spiral threads. UPC and LPC weak with reduced sculpture and single vaguely beaded spiral thread intercalated. Spiral cords even less differentiated on last whorl. Periphery formed by blunt keel; whorls attached slightly below. Base low, faintly concave directly below keel, weakly convex below. About four slightly more prominent, very indistinctly beaded spiral cords on base close to periphery. Basal field with numerous delicate spiral threads and weak axial folds strengthening somewhat towards umbilicus, but remaining relatively weak. No PUC developed. UC small, indistinct, poorly delimited from basal field. Umbilicus narrowly funnel-shaped, moderately wide (~29–33% of total diameter). Umbilical wall with prominent, prosocline growth lines and narrow central spiral cord. Aperture subquadratic with distinct peripheral angulation and weak CG and PG.
Discussion. Solatisonax tavianii differs from other Paratethyan species in its reduced sculpture and the delicate axial ribs along the subsutural cord. Slightly swollen prosocline axial ribs are also developed by the Pliocene Mediterranean Solatisonax hemisphaerica (G. Seguenza, 1876) and the Pleistocene and extant Mediterranean Solatisonax bannocki (Melone & Taviani 1985) (Melone & Taviani 1985: fig. 12; Bertolaso & Palazzi 2000: figs 74–78; Negri & Corselli 2016; fig. 16l) [The extant Solatisonax bannocki Melone & Taviani 1985 has been synonymized with the Pliocene Solatisonax hemisphaerica (G. Seguenza, 1876) by Bertolaso & Palazzi (2000: 24). We note however, that the Pliocene species differs in its eponymous high cyrtoconoid shape from extant specimens, which have comparatively compressed shells and more convex spire whorls (see Bertolaso & Palazzi 2000: figs 74–78 and L. Seguenza 1903: pl. 17, figs 9–10 vs Melone & Taviani 1985: fig. 12 and Negri & Corselli 2016: fig. 16l). Tentatively, we would refrain from synonymizing both species without comparison of more material.] The Paratethyan species is closer to the extant species concerning its depressed outline and closer to the Pliocene species concerning the nearly flat spire whorls.
Paleoenvironment. Unknown; probably middle to outer neritic environments.
Distribution. Only known from the Langhian equivalent of the Badenian in the Central Paratethys Sea.
Central Paratethys Sea. Badenian (Middle Miocene): Făget Basin: Lăpugiu de Sus (Romania).
description: Published as part of Harzhauser, Mathias & Landau, Bernard, 2023, The Architectonicidae and Mathildidae (Gastropoda, Heterobranchia) of the Miocene Paratethys Sea-victims of the Miocene Climatic Transition, pp. 1-74 in Zootaxa 5370 (1) on pages 20-22, DOI: 10.11646/zootaxa.5370.1.1, http://zenodo.org/record/10147814