Robbanacca cerovaensis

Robbanacca cerovaensis (Harzhauser in Harzhauser, Mandic & Schlögl, 2011) nov. comb.

Figs 54A–C View FIGURE 54

* Polinices cerovaensis Harzhauser View in CoL nov. sp. — Harzhauser et al. 2011: 213, figs 2.1–3. Type material. Holotype: NHMW 2010/0080/0001, SL: 6.9 mm, MD: 6.5 mm, illustrated in Harzhauser et al. (2011: fig. 2.1), Fig. 54A View FIGURE 54 . Paratypes: NHMW 2010/0080/0002, SL: 9.1 mm, MD: 7.0 mm, illustrated in Harzhauser et al. (2011: fig. 2.2), Fig. 54B View FIGURE 54 . NHMW 2010/0080/0002, SL: 3.2 mm, MD: 2.6 mm, illustrated in Harzhauser et al. (2011: fig. 2.3), Fig. 54C View FIGURE 54 .

Revised description. Very small, ovate shell of ~3.5 teleoconch whorls (SL/MD = ~1.0–1.3). Protoconch strongly depressed, amlost planispiral, of 1.7 convex whorls. Spire moderately elevated; apical angle 100°. Suture linear, narrowly impressed. Teleoconch whorls with steep, moderately wide, slightly concave subsutural ramp, delimited by faint shoulder angulation. Last whorl ovate, weakly expanding, attaining ~85% of total height. Periphery moderately convex. Growth lines distinct at adapical suture, weakly prosocyrt in apical view, delicate at periphery. Aperture narrow, ovate. Adapical tip of aperture distinctly below shoulder, above mid-whorl. Aperture attaining ~75% of total height. Columellar lip, basal lip and outer lip thin. Columellar angle ~25°. Opercular ridge unknown. Umbilicus reduced by large umbilical callus to narrow, shallow umbilical chink. Parietal callus small, weakly thickened, not expanding, grading into comparatively large, knob-like anterior lobe. Large, thickened, trigonal umbilical callus, separated from anterior parietal lobe by deep transverse groove. Basal fasciole rounded. Uniformly tan color.

Discussion. This species is characterized by its nearly planispiral protoconch, elongate-ovate outline, knob-like anterior lobe and plug-like umbilical callus, which are separated by a deep transverse groove. We did not trace any similar species in the literature, which might result from the fact that Miocene bathyal mollusc faunas are rarely reported.

Robbanacca cerovaensis (Harzhauser in Harzhauser, Mandic & Schlögl, 2011) was placed in Pliconacca by Robba et al. (2016: 195), which is rejected herein, as we do not consider the umbilical features of the Eocene Indonesian Pliconacca to be homologous (see discussion above). Moreover, Robba et al. (2016: 195) assumed a close relation between Robbanacca cerovaensis and Natica plicatulaeformis Kittl, 1887 , which was also placed in Pliconacca by these authors. This relationship is unlikely, as Natica plicatulaeformis and Natica prohelicina ( Sacco, 1890) both differ from Robbanacca cerovaensis in their globular outline, marked subsutural axial plicae and the open umbilicus, which lacks a plug-like umbilical callus. Moreover, the protoconch of N. plicatulaeformis and N. prohelicina is low turbiniform. Therefore, these two species are separated herein from Robbanacca and Pliconacca and are placed in Tethynices nov. gen.

Paleoenvironment. Upper bathyal soft bottoms ( Harzhauser et al. 2011).

Distribution in Central Paratethys. Early Miocene (Karpatian): Vienna Basin: Cerová-Lieskové ( Slovakia).

Genus Tethynices nov. gen.

Type species. Natica plicatulaeformis Kittl, 1887 . Middle Miocene , Czech Republic, Central Paratethys Sea .

Etymology. Combination of Tethys , referring to the Tethys Ocean , and - nices from Polinices .

Diagnosis. Small to medium sized, globose shell with weakly elevated spire composed of strongly convex whorls; suture narrow but deeply incised; prominent prosocline subsutural axial plicae in apical view; spherical last whorl and narrow open umbilicus with prominent, thickened parietal callus passing into small, tongue-like anterior parietal lobe, fused with narrowly trigonal umbilical callus; with weak to subobsolete transverse groove below anterior lobe.

Description. See description for type species.

Included species. Natica plicatulaeformis Kittl, 1887 , Badenian (Middle Miocene), Czech Republic. Natica ( Naticina) catena var. prohelicina Sacco, 1890 , Burdigalian and Langhian of Italy ( Sacco 1891: 67, pl. 2, fig. 38) [including synonyms: Natica ( Naticina) catena var. ampullinoides Sacco, 1890 ( Sacco 1891: 67, pl. 2, fig. 39); Natica ( Naticina) catena var. cyclostomoides Sacco, 1890 ( Sacco 1891: 68, pl. 2, fig. 40); Natica ( Naticina) catena var. tauroumbilicata Sacco, 1891 ( Sacco 1904: 102, pl. 22, fig. 27); Natica ( Naticina) catena var. scalarioides Sacco, 1891 ( Sacco 1904: 102, pl. 22, fig. 28); Natica ( Naticina) catena var. subhemiclausa Sacco, 1891 , Sacco 1904: 103, pl. 22, fig. 30)].? Pliconacca atricapilla sensu Majima, 1989 [ non Martin 1884], Pliocene and early Pleistocene of Japan ( Majima 1989: 64, pl. 1 figs 13–16).

Discussion. Tethynices nov. gen. is characterized by its globose outline, convex spire whorls, prominent subsutural axial plicae and rather simple umbilical features with a weak transverse groove below the anterior parietal lobe. These features are developed by the Paratethyan Natica plicatulaeformis Kittl, 1887 and Natica prohelicina Sacco, 1891 from the Early Miocene of the Proto-Mediterranean Sea. Already Robba et al. (2016) recognized the similarities between these species and considered them to be conspecific. Herein, we do not follow this concept because Tethynices prohelicina attains more than twice the size of Tethynices plicatulaeformis being up to 23 mm in height. Moreover, the parietal callus is much weaker in T. prohelicina and its umbilicus is wider. Finally, T. prohelicina derives from coastal marine deposits of the Colli Torinesi (Burdigalian: Valle Ceppi, Langhian: Villa Forzano, Italy), whereas Tethynices plicatulaeformis is an offshore species. See Robba et al. (2016: fig. 12/10) for the protoconch of Tethynices prohelicina .

The vague concept of Pliconacca (see discussion on Robbanacca nov. gen.) led Robba et al. (2016) to place the Miocene Natica plicatulaeformis Kittl, 1887 and Natica prohelicina Sacco, 1891 in Pliconacca . However, these species have an open umbilicus, and a single short transverse fold and are, in our opinion, unrelated to Pliconacca and Polinella . Instead, these species might be congeneric with an unnamed species from the Pliocene/Pleistocene of Japan, erroneously described by Majima (1989) as Pliconacca atricapilla . The Japanese species differs from the much older Indonesian Polinella atricapilla ( Martin, 1884) in its globose outline, narrower and more convex subsutural ramp, and wider columellar angle (compare Leloux & Wesselingh 2009: pl. 202, figs 10–11 versus Majima 1989: pl. 1 figs 13–16). Herein, we tentatively also place the Japanese species in Tethynices nov. gen.

Paleoenvironment. The type species was found in offshore clays, whereas Tethynices prohelicina ( Sacco, 1890) derives from shallow marine environments and glauconitic sand.

Distribution. Burdigalian and Langhian of the Proto-Mediterranean Sea and Langhian (Badenian) of the Central Paratethys Sea.? Pliocene/Pleistocene of Japan ( Kochi, Okinawa and Shizuoka Prefectures) ( Majima 1989).