Helminthia orthezensis (Tournouër in de Bouillé, 1875)

Harzhauser, Mathias & Landau, Bernard, 2019, Turritellidae (Gastropoda) of the Miocene Paratethys Sea with considerations about turritellid genera, Zootaxa 4681 (1), pp. 1-136 : 44-45

Helminthia orthezensis (Tournouër in de Bouillé, 1875)

Figs 6N , 13 J 1 – J 2

* Turritella Orthezensis new sp. — Tournouër in de Bouillé, 1875: 88, pl. 1, figs 1a–1b.

Turritella (Torculoidella) orthezensis Tournouër — Cossmann & Peyrot, 1922: 46, nr. 433, pl. 2, figs 43–44.

T [urritella]. (T [orculoidella]. orthezensis Tourn. — Sieber, 1958a: 138.

Turritella (Torculoidella) orthezensis Tourn. — Sieber, 1960: 260, pl. 2, figs 29–29a, pl. 3, fig. 8/21.

[ Turritella bicarinata Eichwald , sp. 1830] var. orthezensis Tournouër, 1875 — Glibert, 1962: 88 (pars).

Archimediella Archimediella [sic] orthezensis orthezensis Tournouer — Stürmer, 1989: 148, pl. 7, figs 3–4, pl. 10, fig. 9. Turritella orthezensis Tourn. — Schultz, 1965: 284.

non T. (Eichwaldiella) bicarinata orthezensis Tourn. — Brébion, 1967: 297, fig. 2 [= Oligodia bicarinata ( Eichwald, 1830) ]

Type material. Syntypes from Orthez (Le Paren) in France (Serravallian) might be stored in the Muséum National d’Histoire Naturelle, Paris, but could not currently be located (Jean-Michel Pacaud pers. comm., 2019) .

Studied material. 1 spec. NHMW 1963/0515/0000, Braunsdorf ( Austria) .

Illustrated material. Figs 13J 1 –J 2 : Braunsdorf ( Austria): SL: 41.3 mm, MD: 13.8 mm, NHMW 1963/0515/0000.

Revised description. Shell small, moderately slender, of slightly cyrtoconoid profile. Protoconch and earliest teleoconch whorls unknown. Earliest preserved teleoconch whorl unicarinate with prominent B spiral cord, smooth, slightly concave sutural ramp and weak C and d spiral cords of equal strength. Soon, A spiral cord appears as prominent spiral cord. Adult whorls with prominent B spiral cord, slightly weaker A cord and closely spaced C and d cords of which d spiral cord is more prominent, protruding over abapical suture. All spiral cords develop into broad, prominent cords with convex tops during ontogeny. Entire shell, including spiral cords, covered by densely spaced spiral threads. Lateral sinus angle low to moderately steep, ranging around 11°; wide, moderately deep, maximum distinctly in adapical third of whorl; distinct inflection point below adapical suture, weaker inflection point close to base; basal sinus weakly opisthocyrt. Base nearly flat with four prominent spiral cords. Aperture low subquadratic; columella moderately concave, inner lip broad, reflected, forming narrow umbilical chink. No information on inner lirae.

Shell measurements and ratios. Only a single specimen is available; AA: ~24°, PA: 20°, Lateral sinus (n = 7): LS angle = 11.0° (σ =1.9°), LS p = 0.76 (σ = 0.14), LS d = 5.5 (σ = 1.18).

Discussion. Glibert (1949, 1962) treated Turritella orthezensis as subspecies of Turritella bicarinata Eichwald, 1830 . He illustrated two specimens from the middle Miocene of the Loire Basin as Turritella (Archimediella) bicarinata Eichwald, 1853 ( Glibert 1949, pl. 6, fig. 17b–c), which he considered as T. b. orthezensis in the discussion ( Glibert 1949: 118). This view was also followed by Brébion (1967). Nevertheless, Helminthia orthezensis differs from the widespread and highly variable Oligodia bicarinata in its prominent A spiral cord, and in the bifid spiral cord at the abapical suture (C and d spiral cords), which appear during a very early stage of growth. Based on these differences in sculpture of neanic whorls we reject a placement in Oligodia . The late appearance of the A spiral cord is reminiscent of Helminthia tricincta and H. vermicularis and already Tournouër (1875) emphasized the similarity with Turritella riepeli [= Helminthia tricincta ( Borson, 1821) ].

Paleoenvironment. The species was described by Tournouër in de Bouillé (1875) along with a diverse inner shelf mollusc fauna. A similar depositional setting can be assumed for the Paratethyan occurrence at Braunsdorf ( Austria) (herein).

Distribution. Western and Central Paratethys. Ottnangian (early Miocene): North Alpine Foreland Basin: Rainbach, Höbmannsbach, Haselbach ( Austria) ( Schultz 1965). Badenian (middle Miocene): North Alpine Foreland Basin: Braunsdorf ( Austria) ( Sieber 1960). Proto-Mediterranean Sea and northeastern Atlantic. Serravallian (middle Miocene): Aquitaine Basin: Orthez (Le Paren), Salies-de-Béarn ( France) ( Cossmann & Peyrot 1922).

Figures

FIGURE 1. Paleogeography of the Paratethys during the early Miocene (Burdigalian, Eggenburgian, Sakaraulian) and the middle Miocene (Langhian, Badenian, Tarkhanian) (modified after Popov et al. 2004 and Neubauer et al. 2015).

FIGURE 2. Miocene chronostratigraphy after Gradstein et al. (2012) with regional Paratethys stages after Popov et al. (2004) and Piller et al. (2007).

FIGURE 6. Growth line traces of Turritellidae species based on own data; bold: type species of genera; black: Paratethyan species; asterisk: non-Paratethyan species (unknown basal sinuses are left blank).

FIGURE 13. A–C. Helminthia tricincta (Borson, 1821). A. Lăpugiu de Sus (Romania), NHMW 1870/0033/0155. B1–B2. Steinebrunn (Austria), NHMW 1846/0037/0382. C. Sedlec (Czech Republic), NHMW 1858/0047/0035. D–F. Helminthia vermicularis (Brocchi, 1814). D1–D2. Steinebrunn (Austria), NHMW 1860/0001/0275a. E1–E2. Gainfarn (Austria), NHMW 1862/0001/0391. F. Lăpugiu de Sus (Romania), NHMW 2018/0181/0001. G–I. Helminthia doublierii (Matheron, 1842). G. Maigen (Austria), NHMW 2018/0191/0002. H. Maigen (Austria), NHMW 2018/0191/0001. I. Maigen (Austria), digitally restored specimen. J1–J2. Helminthia orthezensis (Tournouër in de Bouillé, 1875), Braunsdorf (Austria), NHMW 1963/0515/0000, K–M. Helminthia taurobrocchii (Sacco, 1895). K. Mörtersdorf (Austria), NHMW 2012/0017/0328. L. Mörtersdorf (Austria), NHMW 2012/0017/0329. M1–M2. Holotype, Torino Hills (Italy), BS.061.04.038.