Acirsa plana Csepreghy-Meznerics, 1950

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 : 19-20

Acirsa plana Csepreghy-Meznerics, 1950

Figs 6D

* Acirsa plana n. sp. Csepreghy-Meznerics 1950: 33, pl. 2, fig. 6.

Brotia escheri inornata Wenz — Csepreghy-Meznerics 1950: 26, pl. 1, fig. 9 [non Tinnyea inornata ( Wenz, 1932) ].

Acirsa pelagica plana Csepreghy-Meznerics 1950 — Strausz 1966: 179, pl. 2, fig. 1.

Acirsa plana Csepreghy-Meznerics, 1950 — Pálfy et al. 2008: 104.

Type material. Holotype, M.63.7792, SL: 14.8 mm, MD: 5.0 mm, Hidas , MÁSZ drill core ( Hungary), illustrated in Csepreghy-Meznerics (1950: pl. 2, fig. 6), Figs 6D .

Revised description. Shell medium-sized, slender conical (apical angle ~17°). Protoconch and early teleoconch unknown. Teleoconch of weakly convex whorls, periphery placed mid-whorl. Suture moderately impressed, linear, slightly emphasized by narrow, convex subsutural spiral cord. Sculpture strongly reduced, comprising few broad, indistinct spiral cords. No axial sculpture. Base of last preserved whorl with rounded angulation. Last whorl and aperture unknown.

Discussion. This is a poorly known species, which was based on a single fragmentary and probably worn specimen. A second, more complete specimen was confused by Csepreghy (1950) with the freshwater dwelling Pachychilidae genus Tinnyea Hantken, 1887 . Unfortunately, the specimen is lost (pers comm. Alfréd Dulai, 04.11.2024). Tinnyea inornata ( Wenz, 1932) has a comparable spire with weak sculpture but has a very large aperture (see Wenz 1932, pl. 1, fig. 3).

The extant Mediterranean-northeastern Atlantic Acirsa subdecussata ( Cantraine, 1835) is most similar and differs only in its more prominent spiral cords. Given the poor preservation of the holotype, it is difficult to evaluate the value of this difference. Acirsa miopedemontana Sacco, 1891 , from the Burdigalian of Baldissero ( Italy), is stockier and differs in its more convex whorls and more prominent spiral sculpture ( Sacco 1891: pl. 2, fig. 103).

Paleoenvironment. Shallow marine, inner neritic.

Distribution in Central Paratethys. Badenian (Middle Miocene): Pannonian Basin: Hidas ( Hungary).

Genus Acrilloscala Sacco, 1890

Type species. Turbo geniculatus Brocchi, 1814 ; original designation by Sacco (1890: 321, footnote). Pliocene, Italy.

Diagnosis. “ Medium thick shell . Medium size ; shape narrow, turriculate; spire long, with regularly conical curve, polygyrate; protoconch smooth, acute, styliform; whorls convex, separated by deep, but continuous sutures; ornamentation composed of fine axial lamellae, not very prominent, slightly inclined, not deviated on the sutures, where they join the corresponding lamella of the previous whorl by a cochleariform inflexion; in their intervals, an excessively fine lattice of spiral striae and growth lines can be distinguished with a magnifying glass. Last whorl not very high, not reaching a quarter of the total height, subangular at the periphery of the base, which is covered by a thin, opaline disc, crossed by lamellae that then converge towards the imperforate center, where there is a very slight bulge with a rudimentary auricle. Circular aperture, with a slightly calloused, almost discontinuous peristome, the inner layer tapering completely to the parietal region; slightly oblique peristome, broadly bordered on the outside. ” (translated from Cossmann 1912: 65).

“ Acrilloscala can be used for a group of Pliocene and Recent E. Atlantic species characterized by a poorly defined basal disc over which the axial ribs extend. ” ( Bouchet & Warén 1986).

Discussion. The genus is still represented by two species: Acrilloscala fusca (G.B. Sowerby II, 1844) from the tropical eastern Atlantic and the Cape Verde Archipelago ( Gofas et al. 1985; Rolán 2005), and Acrilloscala lamyi (de Boury, 1909) , from the northeastern Atlantic and the Cape Verde Islands (de Boury 1909b; Bouchet & Warén 1986; Rolán 2005). Fossil records are also confined to the northeastern Atlantic, Proto-Mediterranean Sea and Central Paratethys Sea ( Sacco 1891; Cossmann 1912; hoc opus).

Figures

FIGURE 6. A–B. Acirsa fusiformis sp. nov., A1–A2. Holotype, NHMW 1873/0026/0043, Lăpugiu de Sus (Romania). B1– B2. Paratype, NHMW 1873/0026/0043a, Lăpugiu de Sus (Romania). C1–C2. Acirsa koskeridouae sp. nov., holotype, NHMW 1860/0001/0289, Steinebrunn (Austria). D. Acirsa plana Csepreghy-Meznerics, 1950, holotype, M.63.7792, Hidas (Hungary).