Bittium amibouei, Harzhauser & Guzhov & Landau, 2025

Bittium amibouei sp. nov.

Figs 5A–G View FIGURE 5

Cerithium scabrum Olivi— Hörnes 1855 View in CoL (pars): 410 [non Bittium scabrum (Olivi, 1792) View in CoL ].

Bittium reticulatum View in CoL ( da Costa, 1778)— Tomašových 1998: 374, pl. 3, figs 10–11, pl. 9, figs 6–7 [non Bittium reticulatum View in CoL ( da Costa, 1778)].

Bittium reticulatum View in CoL — Zuschin et al. 2007: 288 [non Bittium reticulatum View in CoL ( da Costa, 1778)].

Type material. Holotype NHMW 1864 View Materials /0001/0206, SL: 11.0 mm, MD: 3.3 mm, Gainfarn ( Austria), Figs 5D View FIGURE 5 1 – D View FIGURE 1 2 View FIGURE 2 . Paratypes: NHMW 2023 View Materials /0048/0002, SL: 9.0 mm, MD: 2.9 mm, Gainfarn ( Austria), Figs 5A View FIGURE 5 1 –A View FIGURE 1 2 View FIGURE 2 . NHMW 2023 View Materials /0048/0003, SL: 8.0 mm, MD: 2.5 mm, Gainfarn ( Austria), Figs 5B View FIGURE 5 1 –B View FIGURE 1 2 View FIGURE 2 . NHMW 2023 View Materials /0048/0004, SL: 8.0 mm, MD: 2.5 mm, Gainfarn ( Austria), Figs 5C View FIGURE 5 1 –C View FIGURE 1 2 View FIGURE 2 . NHMW 2023 View Materials /0048/0005, SL: 5.0 mm, MD: 2.2 mm, Gainfarn ( Austria), Fig. 5E View FIGURE 5 . NHMW 2023 View Materials /0048/0006, SL: 6.2 mm, MD: 2.3 mm, Gainfarn ( Austria), Fig. 5F View FIGURE 5 . NHMW 2023 View Materials /0048/0007, SL: 6.1 mm, MD: 2.4 mm, Gainfarn ( Austria), Fig. 5G View FIGURE 5 .

Additional material. 8 spec., NHMW 1864 View Materials /0047/0001, Gainfarn ( Austria) ; 326 spec., NHMW 2013 View Materials /0479/0866, Gainfarn ( Austria) ; 470 spec., NHMW 2013 View Materials /0479/0864, Gainfarn ( Austria) ; 175 spec., NHMW 2013 View Materials /0479/0869, Gainfarn ( Austria) ; 588 spec., NHMW 2013 View Materials /0479/0863, Gainfarn ( Austria) ; 15 spec., NHMW 2013 View Materials /0479/0867, Gainfarn ( Austria) ; 96 spec., NHMW 2013 View Materials /0479/0871, Gainfarn ( Austria) ; 139 spec., NHMW 2013 View Materials /0479/0865, Gainfarn ( Austria) ; 179 spec., NHMW 2013 View Materials /0479/0868, Gainfarn ( Austria) .

Type locality. Gainfarn ( Austria), Vienna Basin .

Type stratum. Silt sand of the Baden Formation.

Age. Middle Miocene, middle Badenian (Langhian).

Etymology. Referring to the French geologist Ami Boué (1794–1881), who was the first to study the mollusks from Gainfarn ( Austria).

Diagnosis. Medium sized, slender conical shell characterized by a protoconch of 2.5 whorls with faint spiral thread on last whorl, teleoconch sculpture of three prominent spiral cords crossed by axial ribs of equal strength forming cancellate sculpture. Varices very prominent, roughly axially aligned.

Description. Medium sized, slender conical shell of up to 14 teleoconch whorls, attaining ~ 11 mm in height; apical angle ~22–25°. Protoconch high conical of 2.5 convex whorls (dp = 270 μm). Last protoconch whorl with faint spiral thread at abapical suture. First teleoconch whorl with moderately wide subsutural ramp and two prominent spiral cords. Prominent, narrow axial ribs appear on second teleoconch whorl, forming cancellate sculpture with large tubercles developed at intersections. Third spiral cord appears over subsutural ramp on second or third teleoconch whorl. Later teleoconch whorls conical, straight sided with deeply incised, linear to weakly undulating suture. Sculpture of three prominent spiral cords and weaker axial ribs. Sculpture rather close set on early spire whorls; wide cancellate sculpture on later whorls. Fourth spiral cord at abapical suture, largely covered by subsequent whorl. Varices broad, strengthening further during ontogeny, often being roughly axially aligned along length of teleoconch. Last whorl weakly convex with markedly constricted base, attaining ~33 % of total height. Transition into base weakly angulated with two raised peribasal cords. Two additional spiral cords over fasciole. Aperture ovate, relatively small. Columella weakly excavated. Columellar callus forming indistinct, narrow rim. Anal canal indistinct. Outer lip not preserved. Three blunt denticles inside aperture corresponding to varix of last whorl. Siphonal canal narrow, short.

Discussion. This species is among the larger sized Bittiinae of the Central Paratethys Sea and occurs in huge numbers at the type locality, where it is among the dominant mollusk species ( Zuschin et al. 2007). Since Hörnes (1855), however, it has been confused with Bittium reticulatum ( da Costa, 1778), from which it differs quite clearly by the presence of only three spiral cords and by the cancellate sculpture in Bittium amibouei sp. nov. The same features allow a separation from Bittium tani sp. nov. The prominent varices and the presence of three primary spiral cords in B. amibouei are reminiscent of Bittium deforme ( Eichwald, 1829) , but that species is also clearly distinguished by its close-set beads. Bittium courtillerianum ( Millet, 1865) , from the Tortonian of France, has very similar sculpture on late teleoconch whorls, but has convex early whorls and a short protoconch of only one whorl (see Landau et al. 2018: pl. 4). Bittium courtillerianum ( Millet, 1865) var. sensu Landau et al. (2018) , from the Tortonian of France, also has a cancellate sculpture, but develops four spiral cords, has more convex whorls and especially its early teleoconch whorls differ in their convexity (see Landau et al. 2018: pl. 5).

Paleoenvironment. Shallow marine, inner neritic with sea grass cover ( Zuschin et al. 2007).

Distribution. Badenian of the Central Paratethys Sea.

Central Paratethys. Badenian (Middle Miocene): Vienna Basin: Gainfarn ( Austria); Devínska Nová Ves ( Slovakia).