Solatisonax transversa 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 transversa

description: Solatisonax? transversa nov. sp.
Figs 4J, 11A 1 –A 3
Architectonica carocollata (Lam.) juv. an n. sp.— Báldi 1960: 60, pl. 1, figs 8a–b [non Simplexollata carocollata (Lamarck, 1822)].
Type material. Holotype: NHMW 2016 /0177/0341, SL: 1.8 mm, MD: 6.7 mm, Lăpugiu de Sus (Romania), Figs 4J, 11A 1 –A 3.
Additional material. 1 spec., Szokolya (Hungary), SL: 3.6 mm, MD: 7.0 mm, Hungarian Natural History Museum, illustrated in Báldi (1960: pl. 1, figs 8a–b).
Type locality. Lăpugiu de Sus (Romania).
Type stratum. Silt and clay of the Dej Formation.
Age. Middle Miocene, early/middle Badenian (Langhian).
Etymology. From Latin transversus (= oblique), referring to the prosocline axial ribs.
Diagnosis. Small, moderately elevated lentiform shell with low conical spire, characterized by prosocline axial ribs between beaded SSC and UPC and wide basal field with reduced spiral sculpture and prominent axial folds.
Description. Small, moderately elevated lentiform shell with low conical spire and angulated periphery. Protoconch, heterostrophic, medium-sized of <1 visible whorls (diameter 1.1 mm). Teleoconch of about 3.75 whorls. Teleoconch whorls nearly flat. Early teleoconch whorls with beaded SSC, beaded UPC and prominent, nearly smooth LPC. No MCs; instead, mid-whorl with densely spaced, prominent, prosocline axial ribs. SSC fading on second teleoconch whorl. Beads on UPC fade on third teleoconch whorl. Periphery formed by blunt keel; whorls attached slightly below keel. IPC forming distinctly weaker angulation below keel. Base with nearly smooth LPC and IPC, three weaker spiral cords intercalated. Basal field lacking spiral sculpture except for few weak spiral threads close to IPC. Basal field with long, narrow, prominent axial folds strengthening towards umbilicus; partly bifurcating towards IPC. No PUC. UC tubercular, overhanging umbilicus, weakly delimited from basal field by narrow shallow groove. Umbilicus narrowly funnel-shaped, moderately wide (~28% of total diameter). Umbilical wall with prominent prosocline growth lines. Aperture subquadratic with moderate peripheral angulation and distinct, shallow CG, no PG.
Discussion. The placement in Solatisonax is tentative. Axial ribs occur in several extant species, such as S. atkinsoni (Smith, 1891), S. acutecarinata (Thiele, 1925) and S. supraradiata (von Martens, 1904). Solatisonax supraradiata is especially similar to S. transversa concerning the wide basal field with axial ribs and has a comparably prominent IPC (see Bieler 1993; fig. 139). The Pliocene Mediterraean Solatisonax pliohumilis (Chirli, 2013) is superficially similar but lacks the angulation by the IPC, has less prominent axial sculpture, and has a narrower umbilicus (see Chirli 2013: pl. 5, figs 1–5). Solarium (Nipteraxis) peyreirense Cossmann & Peyrot, 1919 (Cossmann & Peyrot 1919: 462, pl. 15, figs 45–47), from the Chattian of Peyrehorade (France), is reminiscent of the Paratethyan species in its sculpture on the dorsal side but differs distinctly in its much larger and coarser UC and fewer blunter axial folds on the basal field. Placement in the genus Nipteraxis Cossmann, 1916 [type species Solarium plicatum Lamarck, 1804; Eocene, France], as proposed by Cossmann & Peyrot (1919), is rejected herein for ‘ Solarium ’ peyreirense and for Solatisonax transversa, as Nipteraxis species have a wider umbilicus and prominent beaded spiral cords on the basal field.
Paleoecology. Unknown; probably outer neritic environments, which are typical for many Solatisonax species (Bieler 1993).
Distribution. Only known from the Langhian equivalent of the Badenian in the Central Paratethys Sea.
Central Paratethys Sea. Badenian (Middle Miocene): Pannonian Basin: Szokolya (Hungary), 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 page 22, DOI: 10.11646/zootaxa.5370.1.1, http://zenodo.org/record/10147814