Opaliopsis compacta, Harzhauser & Landau, 2025

Opaliopsis compacta sp. nov.

Figs 1A–B View FIGURE 1 , 2H View FIGURE 2

Type material. Holotype, NHMW 2024 View Materials /0285/0001, SL: 4.8 mm, MD: 2.0 mm, Porzteich at Břeclav ( Czech Republic), Figs 1A 1 –A View FIGURE 1 2, 2H View FIGURE 2 . Paratype, NHMW 2024 View Materials /0285/0002, SL: 3.9 mm , MD: 1.6 mm, Porzteich at Břeclav ( Czech Republic), Figs 1B 1 –B View FIGURE 1 2 View FIGURE 2 .

Type locality. Porzteich at Břeclav ( Czech Republic), Vienna Basin .

Type stratum. Baden Formation.

Age. Middle Miocene, middle Badenian (Langhian).

Etymology. From compactus (Latin for compact, stout), referring to the shape.

Diagnosis. Very small, moderately slender, faintly cyrtoconoid shell with relatively low subcylindrical whorls, deeply incised suture and prominent axial ribs separated by interspaces of about equal width, overrun by six much weaker spiral cords, aperture subcircular, small, duplex.

Description. Shell very small, moderately slender turriculate, faintly cyrtoconoid, apical angle ~23°). Protoconch unknown. Teleoconch of at least seven relatively low whorls. Early teleoconch whorls weakly convex, later whorls becoming subcylindrical. Suture deeply impressed, slightly undulating. Sculpture of prominent, orthocline axial ribs, not aligned axially (13: 13: 14), separated by slightly wider interspaces, overrun by six very weak, somewhat blurred spiral cords, most prominent in axial interspaces, separated by narrower grooves. Last whorl attaining about 35% of total height, distinct basal angulation delimited by prominent peribasal cord, basal disc with slightly scalloped margin, bearing weak axial ribs and two indistinct spiral cords. Aperture small, subcircular. Outer lip slightly thickened. Columellar and parietal callus forming continuous, narrow rim, detached from base. Peristome duplex. Umbilicus reduced to very narrow chink.

Discussion. Opaliopsis savii ( Bogi & Cauli, 1998) , from the Pliocene of Italy, has a higher last whorl, prosocline axial ribs and more prominent spiral cords (see Bogi & Cauli 1998: figs 4–5). Opaliopsis cf. savii ( Bogi & Cauli, 1998) , from the Pliocene of Spain, differs also in its more prominent spiral sculpture but is otherwise very similar to Opaliopsis compacta (see Landau et al. 2006: pl. 5, figs 1–2). Opaliopsis compacta sp. nov. is reminiscent of the Mediterranean Punctiscala cerigottana ( Sturany, 1896) but lacks a punctate microsculpture typical of that genus (see Weil et al. 1999: fig. 122).

Paleoenvironment. Unknown.

Distribution in Central Paratethys. Badenian (Middle Miocene): Vienna Basin: Porzteich at Břeclav ( Czech Republic) (hoc opus).

Genus Papuliscala de Boury, 1911

Type species. Acirsa praelonga Jeffreys, 1877 View in CoL ; original designation. Present-day , eastern Atlantic .

Diagnosis. “ Shell turriculate, teleoconch with several whorls of somewhat rounded outline; with or without carina. Teleoconch sculpture of usually equally strong axial and spiral cords, forming weak to strong nodules on intersections; with development of peripheral basal spiral cord, without umbilicus; basal area with weak to nearly obsolete sculpture. ” ( Pimenta et al. 2018: 20).

Discussion. Miocene species of this genus have sometimes been misplaced in Triphoridae by Boettger (1907), Zilch (1934) and Bałuk (2006). Therefore, Papuliscala was not reported from the Paratethys Sea until now. This is surprising considering its remarkable diversity of six species documented herein. Similarly, the extant diversity of the genus has been strongly underrated until the paper by Hoffman et al. (2020), which more than doubled the number of known species. Currently, 19 extant species are listed by MolluscaBase eds (2024b). Papuliscala was placed in Nystiellinae Clench & Turner, 1952 by Bouchet & Warén (1986: 494) on the base of an axially ribbed, multispiral protoconch of one Oligocene species. All extant species have paucispiral protoconchs. Papuliscala koeneni (A.W. Janssen, 1967) , from the Miocene of the North Sea, also has a multispiral protoconch (see A.W. Janssen, 1967, pl. 14, fig. 2). Herein, we document Papuliscala aquaensis sp. nov. as a further fossil species with a ribbed, multispiral protoconch. This is one of the genera that has lost its planktotrophic mode of development over time so that all extant species have paucispiral protoconchs (see also Landau et al. in press).