Helminthia praevaricosa ( Sieber, 1960 ) Harzhauser & Landau, 2019

Harzhauser, Mathias & Landau, Bernard, 2019, Turritellidae (Gastropoda) of the Miocene Paratethys Sea with considerations about turritellid genera, Zootaxa 4681 (1), pp. 1-136 : 46-48

Helminthia praevaricosa ( Sieber, 1960) new comb.

Figs 6O , 14A 1 –A 2 , 14B, 14C, 14D

T [urritella]. (Torc [uloidella].) praevaricosa— Sieber, 1949: 7 [nomen nudum].

* Turritella (Torculoidella) praevaricosa sp. n. — Sieber, 1960: 260, pl. 2, fig. 28, pl. 3, fig. 8/20.

Turritella (Torculoidella) praevaricosa Sieber, 1960 — Bałuk, 1975: 113, pl. 12, fig. 13.

Archimediella Archimediella [sic] orthezensis praevaricosa Sieber — Stürmer, 1989: 149, pl. 7, figs 1–2, pl. 12, fig. 10. Turcoloidella [sic] praevaricosa ( Sieber, 1960) — Zelei, 2011: 47.

Type material. The holotype NHMW 1963/0514/0000 is a spire fragment found at Windpassing ( Austria); lower Badenian (middle Miocene).

Studied material. 1 spec. NHMW 1963/0514/0000, Windpassing ( Austria) , illustrated in Sieber (1960, pl. 2, fig. 28; 9 spec. NHMW 2018/0299/0001, Pernersdorf ( Austria) ; 3 spec. NHMW 1865/0036/0123, Jerutek at Lysice ( Czech Republic) ; 1 spec. NHMW 2018/0299/0002, 1 spec. NHMW 2018/0299/0003, 1 spec. NHMW 2018/0299/0004, 1 spec. NHMW 2018/0299/0005, 1 spec. NHMW 2018/0299/0006, 1 spec. 2018/0299/0007, 4 spec. NHMW 1971/1422/0005, 17 spec. NHMW 2016/0177/0329, 27 spec. NHMW 2016/0177/0328, 103 spec. 2016/0177/0327, Lăpugiu de Sus ( Romania) .

Illustrated material. Fig. 14A 1 –A 2 : NHMW 2018/0299/0002, SL: 54.0 mm, MD: 15.5 mm; Fig. 14B : NHMW 2018/0299/0003, SL: 52.9 mm, MD: 14.2 mm; Fig. 14C : NHMW 2018/0299/0004, SL: 55.5 mm, MD: 15.3 mm; Fig. 14D : NHMW 2018/0299/0005, SL: 23.9 mm, MD: 7.8 mm; all from Lăpugiu de Sus ( Romania).

Revised description. Shell medium-sized, moderately slender, of about 17 teleoconch whorls. Protoconch unknown. First three neanic whorls convex with incised suture, tricostate (probably B-C-A); B spiral cord passing into sharp keel around 4 th to 5 th teleoconch whorl resulting in keeled to campanulate profile; convexity of whorls decreasing, suture becoming indistinct. B spiral cord successively weakening around seventh to eighth teleoconch whorl resulting in nearly flat sided profile. Spiral cord A nearly fading out on early teleoconch whorls, whereas numerous densely spaced secondary spiral cords appear (also on B spiral cord) separated by narrow interspaces. Two or three secondary spiral cords may amalgamate into more prominent spiral cords, forming five cords on late teleoconch whorls, corresponding in position to r, A, B, C and d spiral cords, with d and C being narrow-spaced. Whorl profile of fully-grown specimens weakly gradate in most specimens or imbricate if d spiral cord is more prominent. Spiral cords indistinctly granulose at intersections with growth lines. Lateral sinus with moderately steep angle; moderately deep with vertex above mid-whorl; adapical part with faint inflection point; abapical part with distinct inflection point passing via prosocyrt sinus into moderately deep, opisthocyrt basal sinus. Base nearly flat, covered by 7 to 8 wide-spaced spiral cords and numerous delicate spiral threads. Aperture subquadrate; inner lip straight; parietal callus thin, glossy, narrowly expanding. Inner lirae are observed in few specimens only, consisting of about 6 weak palatal lirae.

Shell measurements and ratios. (n=10): SL = 56.7 mm (σ = 2.5°), MD = 15.5 mm (σ = 0.9°). AA: 22.1° (σ = 1.9°), PA: 14.6° (σ = 0.5°). Lateral sinus (n = 7): LS angle = 10.2° (σ = 3.2°), LS p = 0.8 (σ = 0.1), LS d = 5.6 (σ = 0.8).

Discussion. This species is characterized by its striking change of whorl profile from convex to keeled, campanulate to flat sided gradate or even imbricate. Its sculpture is variable concerning strength of primaries on adult shells and to a lesser extent by the more or less prominent beads and granulae on the spiral cords. Sieber (1960) had only a spire fragment at hand and placed his new species in Torculoidella Sacco, 1895 (= Oligodia Handmann, 1882 ). The order of appearance of the primaries and the overall morphology and sculpture, however, suggest a placement in Helminthia Handmann, 1822 .

Paleoenvironment. Specimens from Windpassing and Pernersdorf (North Alpine Foreland Basin) derive from channels in which shallow marine faunas were transported into deeper habitats (e.g. Zuschin et al. 2004). The frequent occurrence and good preservation at Lăpugiu de Sus ( Romania), in contrast, might indicate a preference for offshore environments in the middle to outer neritic.

Distribution. Central Paratethys. Badenian (middle Miocene): North Alpine Foreland Basin: Windpassing, Pernersdorf ( Austria) ( Sieber 1960; herein); Carpathian Foreland Basin: Jerutek at Lysice (herein), Korytnica ( Poland) ( Bałuk 1975); Eisenstadt-Sopron Basin: Forchtenau ( Austria) ( Sieber 1960); Transylvanian Basin: Lăpugiu de Sus ( Romania) ( Zelei 2011; herein). A further occurrence might be documented by Hinculov (1968) from the Badenian of Valea Sălişte in Romania. The species seems to be restricted to the Langhian part of the Badenian stage; it is unknown so far from upper Badenian deposits.

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 14. Helminthia praevaricosa (Sieber, 1960), Lăpugiu de Sus (Romania) A1–A2. NHMW 2018/0299/0002. B. NHMW 2018/0299/0003. 14C NHMW 2018/0299/0004. 14D. NHMW 2018/0299/0005.