Hemiacirsa miocenica ( Seguenza, 1880 )

Harzhauser, Mathias & Landau, Bernard M., 2025, The Epitoniidae (Gastropoda, Epitonioidea) of the Miocene Central Paratethys Sea-an overwhelming diversity, Zootaxa 5630 (1), pp. 1-142 : 69-71

publication ID	https://doi.org/10.11646/zootaxa.5630.1.1
publication LSID	lsid:zoobank.org:pub:89462472-D932-4255-880F-C6EF15220A31
persistent identifier	https://treatment.plazi.org/id/03D787A4-FFA1-FFA2-FF3F-FB86FCD495F1
treatment provided by	Plazi
scientific name	Hemiacirsa miocenica ( Seguenza, 1880 )
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Treatment

Hemiacirsa miocenica ( Seguenza, 1880)

Figs 24E–G View FIGURE 24 , 26A–G View FIGURE 26

* S [calaria] lanceolata Brocchi Var. miocenica — Seguenza 1880: 114.

[ Scalaria View in CoL ] H [emiacirsa]. lanceolata var. miocenica Seg.— Sacco 1891: 90 , pl. 2, fig. 99.

[ Scalaria View in CoL ] H [emiacirsa]. eoprysmatica (Sacc.) — Sacco 1891: 90.

[ Hemiacirsa lanceolata ] var. miocenica Seguenza, 1880 — Ferrero Mortara et al. 1984: 52.

Type material. Syntypes, Reggio Calabria ( Italy), Tortonian (Late Miocene); the material is lost (pers com. Stefano Dominici, 03. 11. 2024) .

Sacco (1891) illustrated a specimen from the Tortonian of S. Agata ( Italy), BS.030.17.006, SL: 37.0 mm, MD: 7.5 mm, stored in the Museo Regionale di Scienze Naturali Torino ( Italy), illustrated in Sacco (1891: pl. 2, fig. 99), Figs 26D View FIGURE 26 1 –D View FIGURE 1 2 View FIGURE 2 . This specimen, however, is no type specimen.

Illustrated material. NHMW 1854/0035/0311, SL: 23.7 mm, MD: 5.1 mm, Lăpugiu de Sus ( Romania), Figs 26A View FIGURE 26 1 –A View FIGURE 1 2 View FIGURE 2 . NHMW 1863/0015/0202, SL: 22.1 mm, MD: 4.8 mm, Lăpugiu de Sus ( Romania), Figs 26B View FIGURE 26 1 –B View FIGURE 1 2 View FIGURE 2 . NHMW 1865/0001/0243, SL: 23.2 mm, MD: 4.9 mm, Lăpugiu de Sus ( Romania), Figs 26C View FIGURE 26 1 –C View FIGURE 1 2 View FIGURE 2 . NHMW 1867/0019/0254, SL: 31.8 mm, MD: 5.4 mm, CoŞteiu de Sus ( Romania), Figs 24E View FIGURE 24 , 26E View FIGURE 26 1 –E View FIGURE 1 2 View FIGURE 2 . NHMW 2013/0078/0151, SL: 21.3 mm, MD: 4.0 mm, Baden-Sooss ( Austria), Figs 24F View FIGURE 24 , 26F View FIGURE 26 1 –F View FIGURE 1 2 View FIGURE 2 . NHMW 1846/0037/0128, SL: 18.6 mm, MD: 3.8 mm, Baden-Sooss ( Austria), Figs 24G View FIGURE 24 . NHMW 1872/0030/0081, SL: 18.2 mm, MD: 3.3 mm, Baden-Sooss ( Austria), Figs 26G View FIGURE 26 1 –G View FIGURE 1 2 View FIGURE 2 .

Revised description. Shell large, very slender (apical angle ~8–11°). Protoconch unknown. Teleoconch of up to 15 whorls. Early teleoconch whorls moderately convex, with steep, weakly convex subsutural ramp, convex periphery placed just below mid-whorl bearing broad, prominent, slightly drop-shaped axial ribs. Later whorls high, subcylindrical, with very steep, weakly concave subsutural ramp and faintly convex periphery placed below mid-whorl. Suture weakly impressed, slightly undulating. Sculpture of moderately close-set, convex, weakly prosocline, irregular axial ribs, not aligned axially, fading over subsutural ramp (10: 10/11: 8/11), weakening on last whorl.About one slightly broader axial rib per whorl forming indistinct varix. Spiral sculpture appearing around eighth teleoconch whorl consisting of about 14–16 broad, flat spiral cords separated by narrower interspaces. More prominent spiral cord at abapical suture, often hidden by subsequent whorl. Spiral cords prominent in axial interspaces, only slightly weaker over ribs. Last whorl weakly convex to subcylindrical, attaining ~22–26% of total height, with distinct, rounded basal angulation delimited by one or two more prominent peribasal cords, followed by up to 15 spiral cords over flattened base. Aperture elongate ovate with weakly concave columella, widely angled at adapically. Outer lip and basal lip thin. Columellar callus forming moderately broad rim, detached from base, parietal callus forming delicate, narrow, attached rim. Peristome simple. Umbilicus reduced to very narrow chink.

Discussion. The shells from the Vienna Basin differ from those from Romania in the often smaller size (18–22 mm versus 24–36 mm), the usually slenderer shell and the comparatively blurred axial sculpture, which is often strongly reduced on parts of the last whorls. Provisionally, we treat both occurrences as conspecific.

Hemiacirsa superelongata sp. nov. is also very slender but smaller, and has even less convex whorls, more numerous and broader axial ribs and rectangular sculpture on the subsutural ramp. Hemiacirsa taurolanceolata ( Sacco, 1891) , from the Burdigalian of the Colli Torinesi ( Italy), differs in its straight-sided whorls and more prominent, narrower axial ribs (see Sacco 1891: pl. 2, fig. 98 bis). Hemiacirsa prolanceolata ( Sacco, 1891) , from the Langhian of Sciolze ( Italy), is smaller and differs in its opisthocline and sharper axial ribs (see Ferrero Mortara et al. 1984: pl. 6, fig. 15). Hemiacirsa varicosocylindrica ( Sacco, 1891) and Hemiacirsa cristulosa ( Sacco, 1891) , both from the Burdigalian or Langhian of the Colli Torinesi ( Italy), differ in their even slenderer shells with more convex whorls and more prominent axial ribs (see Sacco 1904; pl. 23, fig. 28; Ferrero Mortara et al. 1984: pl. 7, fig. 4). Hemiacirsa lanceolata ( Brocchi, 1814) differs in its subcylindrical whorls and weaker, often blurred axial ribs (see Pinna & Spezia 1978: pl. 60, fig. 3; Cavallo & Repetto 1992: fig. 162; Chirli 2009: pl. 16, figs 13–18). According to Sacco (1891), Hemiacirsa eoprysmatica ( Sacco, 1891) , from the Tortonian of S. Agata and Stazzano ( Italy), differs from H. miocenica ( Seguenza, 1880) only in its slightly wider spaced ribs on the last whorl and is probably a subjective junior synonym of H. miocaenica . However, we have not seen the syntypes of Hemiacirsa eoprysmatica , which were not illustrated by Sacco (1891) or Ferrero Mortara et al. (1984).

Paleoenvironment. Occurrences in the Baden Formation of the Vienna Basin suggest middle to outer neritic settings in up to 250 m water depth ( Kranner et al. 2021) .

Distribution in Central Paratethys. Badenian (Middle Miocene): Vienna Basin: Baden-Sooss ( Austria) (hoc opus). Făget Basin: CoŞteiu de Sus, Lăpugiu de Sus ( Romania) (hoc opus).

Proto-Mediterranean Sea. Tortonian (Late Miocene): Calabria: Reggio Calabria ( Italy) ( Seguenza 1880), Po Basin: S. Agata ( Italy) ( Sacco 1891). Pliocene records mentioned by Sacco (1891) will need verification: Po Basin: (Castelnuovo d’Asti, Zinola, Savona-Fornaci, R. Torsero ( Italy).