Mesalia styriaca, 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 : 100-102

Mesalia styriaca new sp.

Figs 6 Al, 28A, 28B 1 –B 2, 28C

Mesalia (Mesalia) cochleata angulatella Sacco — Sieber, 1960: 265, pl. 1, fig. 22 [non Sacco, 1895, = Mesalia cochleata ( Brocchi, 1814) ].

Mesalia (Mesalia) cochleata angulatella Sacco — Stürmer, 1989: 88, pl. 1, figs 1–2, pl. 10, fig. 14 [non Sacco, 1895, = non Mesalia cochleata ( Brocchi, 1814) ].

Types. Holotype UMJG&P 74.587-1 ( Fig. 28a ), SL = 31.1 mm, MD = 8.5 mm, Wetzelsdorf Wenzelsteffi ( Austria) . Paratypes UMJG&P 74.587-2 ( Figs 28B 1 –B 2 ), SL = 31.4 mm, MD = 8.2 mm, Wetzelsdorf Wenzelsteffi ( Austria) ; UMJG&P 74.587-3 ( Fig. 28C ), SL = 10.6 mm, MD = 4.3 mm, Wetzelsdorf Wenzelsteffi ( Austria); additional paratypes: 3 spec. NHMW 1862/0033/0041, Pöls ( Austria) ; 12 spec. UMJG&P 74.587, 2 spec. UMJG&P 74.588, Wetzelsdorf ( Austria) ; 7 spec. UMJG&P 9147, Kreuzschaller ( Austria) .

Type stratum. Marly clay (‘Tegel’) of the Florian Formation.

Type locality. Wetzelsdorf Wenzelsteffi ( Austria) .

Age. Middle Miocene, Badenian (= Langhian).

Etymology. Referring to the Austrian province Styria.

Description. Shell small, moderately slender turriculate, of 13 teleoconch whorls. Protoconch paucispiral of about 1.5 smooth whorls with large nucleus; protoconch diameter ~600 μm; terminal protoconch whorl slightly angulated below mid-whorl. Early teleoconch whorls keeled, coinciding with rounded B spiral cord; sutural ramp flat to weakly concave. Keel starts close above abapical suture on early teleoconch whorls and moves towards midwhorl during ontogeny, passing into less prominent angulation on last whorls. Faint C and d spiral cords may appear. Entire shell covered by delicate spiral threads, covering also spiral cords. Lateral sinus angle low to moderately steep, ranging around 11°; shallow, simple concave passing via weakly prosocyrt sinus into basal sinus; distinctly adapical LS p. Base rapidly contracting, covered by delicate spiral threads; basal sinus nearly straight to faintly prosocyrt.Aperture oblique ovate; basal lip slightly effusive, inner lip broad, reflected with distinct umbilical chink. Parietal callus thin, not expanding. No inner lirae developed.

Shell measurements and ratios. Complete specimens are rare; based on the largest nearly complete specimens (Holotype, Paratype 1) the maximum SL ranges around 33.5 mm, maximum MD = 8.5 mm. n = 8 specimens: AA: μ = 20.0° (σ = 2.33°), PA: μ = 14.8° (σ = 0.90°). Lateral sinus (n = 6): LS angle = 11.0° (σ = 1.3°), LS p = 0.7 (σ = 0.14), LS d = 7.1 (σ = 1.5).

Discussion. The shells display a marked shift from moderately slender apical angle of about 20° towards a slen- der pleural angle of about 15°. Therefore, juvenile shells are reminiscent of the early Miocene to early Pliocene Mesalia cochleata ( Brocchi, 1814) , as described and illustrated by Chirli (2006), Landau et al. (2004, 2013), and Forli (2009). Due to this similarity, Sieber (1960) identified the Styrian shells as Mesalia (Mesalia) cochleata angulatella Sacco, 1895 , referring to a strongly angulated morphotype of M. cochleata from the Tortonian of the Po Basin.

Fully grown specimens of Mesalia styriaca , however, are distinguished easily from M. cochleata by their slen- der profile, delicate spiral sculpture and persisting angulation. Moreover, M. cochleata is slightly smaller attaining only about 15–30 mm in height ( Chirli 2006; Landau et al. 2013) and has a relatively larger and subcircular aperture. Mesalia miocaenica ( Dollfus, Cotter & Gomes, 1903) , from the late Miocene of the Cacela Basin ( Portugal), differs also in its regularly convex whorls, the slender apical angle and the larger last whorl. The late Miocene Mesalia dertobicincta Sacco, 1895 is a strongly angulated species as well but differs from M. styriaca by its bicarinate teleoconch whorls (see Ferrero-Mortara et al. 1984, pl. 41, fig.11). Mesalia sovisi new sp., from the early and middle Miocene of the Central Paratethys lacks the marked angulation of M. styriaca , has a more obtuse pleural angle and is smaller. Both species seem to have settled different habitats, M sovisi : coastal marine environments versus M. styriaca : middle to outer neritic.

Paleoenvironment. The species is recorded so far only from marly clay of Wetzelsdorf and Pöls in the Styrian Basin. Especially Wetzelsdorf is known for the frequent occurrence of the rostellariid Tibia, which suggest deeper water conditions ( Kronenberg 2008).

Distribution. Central Paratethys. Badenian (middle Miocene): Styrian Basin: Wetzelsdorf at Graz, Pöls ( Austria).

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 28. A–C. Mesalia styriaca new sp., Wetzelsdorf Wenzelsteffi (Austria). A. Holotype, UMJG&P 74.587-1. B1–B2. Paratype, UMJG&P 74.587-2. C. Paratype, UMJG&P 74.587-3. D–E. Mesalia sovisi new sp., Kroužek at Rousínov (Czech Republic). D1–D2. Paratype, NHMW 2018/0175/0002. E1–E2. Holotype, NHMW 2018/0175/0001. F–H. Mesalia bohnhavasae new sp., Pécsszabolcs (Hungary). F. Holotype, MBFSZ 6231. G. Paratype, MBFSZ 6271. H. Paratype, MBFSZ 6254.