Mitrella dacica, Harzhauser & Landau, 2021

Harzhauser, Mathias & Landau, Bernard M., 2021, The Columbellidae (Gastropoda, Buccinoidea) in the Miocene Paratethys Sea — striking diversity of a negelected group, Zootaxa 5025 (1), pp. 1-75 : 21-23

Mitrella dacica nov. sp.

Figs 4D, 8I 1 –I 2

Columbella (Mitrella) carinata Hilber — Hoernes & Auinger 1880: 97 (pars), pl. 12, figs 9a–c [non Mitrella carinata ( Hilber, 1879) ].

Pyrene (Mitrella) hilberiana Mezn. — Csepreghy-Meznerics 1954: 39, pl. 5, fig. 5, pl. 6., fig. 12 [non Mitrella hilberi ( Cossmann, 1901) ].

Columbella (Atilia) hilberi Cossmann — Strausz 1966: 293, pl. 12, fig. 12 [non Cossmann, 1901].

Mitrella (Atilia) hilberi (M. Cossmann, 1901) — Švagrovský 1981: 146, pl. 45, fig. 7 [non Cossmann, 1901].

Type material. Holotype: NHMW1867 /0019/0049, SL: 17.2 mm, MD: 5.4 mm, Coşteiu de Sus ( Romania), illustrated in Hoernes & Auinger (1880, pl. 12, figs 9a–c), Figs 4D, 8I 1 –I 2 .

Type locality. Coşteiu de Sus ( Romania), Făget Basin .

Type stratum. Silt and clay of the Dej Formation.

Age. Middle Miocene, Badenian.

Etymology. Referring to the Roman province Dacia.

Diagnosis. Mitrella species of medium size, slender fusiform profile, high spire, tall multispiral protoconch, flat-sided teleoconch whorls, tall last whorl with high base delimited by basal angulation, and long siphonal canal.

Description. Shell medium sized, slender fusiform, with narrow suture. High conical multispiral protoconch of 3.5 whorls terminating in sinusigera. Teleoconch of eight whorls. First teleoconch whorl moderately convex, subsequent whorls flat-sided with faint subsutural concavity; periphery just above abapical suture. Last whorl high, biconic with high base, delimited by weak basal angulation. Teleoconch whorls with faint spiral threads and broad, flat spiral cords on base and siphonal fasciole. Aperture moderately wide, ovoid. Anal canal indistinct, very broad V-shaped. Outer lip weakly thickened with eight small prominent denticles within, weakening abapically. Siphonal canal long, moderately narrow with deeply notched at tip. Columellar callus forming narrow rim, sharply delimited from base, with five indistinct columellar denticles. Abapically, columellar callus terminating at adapical end of siphonal canal, adapically passing into narrow, weak parietal callus.

Shell measurements and ratios. SL: 17.2 mm, MD: 5.4 mm,AA: 30°, SL/MD: 3.1,AL/AW: 3.2, LWH/AH: 1.3.

Discussion. This species was confused by Hoernes & Auinger (1880), Strausz (1966) and Švagrovský (1981) with Mitrella hilberi ( Cossmann, 1901) due to its slightly angulate base. It is distinguished from that species by its much larger size, comparatively shorter spire, higher last whorl, much weaker basal angulation and smaller and less convex protoconch. Mitrella viallaverniensis (Sacco, 1890) , from the Pliocene of Italy, develops a comparable basal angulation but has a slightly shorter spire, and a shorter last whorl (see Sacco 1890b; Ferrero Mortara et al. 1981, pl. 57, figs 9a–b). Mitrella viallaverniensis sensu Chirli, 2002 is more slender and has a higher spire (see Chirli 2002, pl. 7, figs 9–12). Although we have only a single specimen at hand, the species was wide-spread in the Paratethys as attested by the various reports in the literature.

Palaeoenvironment. Unknown.

Distribution in Central Paratethys. Badenian (middle Miocene): Vienna Basin: Devínska Nová Ves ( Slovakia) ( Švagrovský 1981); Pannonian Basin: Cserhát Mountains: Sámsonháza ( Hungary) ( Csepreghy-Meznerics 1954; Strausz 1966); Făget Basin: Coşteiu de Sus ( Romania).

Figures

FIGURE 1. A. Map of central and south–eastern Europe, representing the area that was partly covered by the Central Paratethys Sea. The white insert corresponds to the area that is restored in the palaeogeographic map below. B. Paleogeography of the Middle Miocene Paratethys Sea showing the most important sedimentary basins (NAFB: North Alpine Foreland Basin, E–Sopr B: Eisenstadt–Sopron Basin).

FIGURE 2. Measurements for shell morphology and whorl profiles. SL: shell length, MD: maximum diameter, AA: apical angle, LWH: last whorl height, AH: aperture height. AL: aperture length. AW: aperture width.