Mitrella elongatissima, 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 : 24-25

Mitrella elongatissima nov. sp.

Figs 4C, 9A 1 –A 2 , B 1 –B 2 , C 1 –C 2 , D

[ Mitrella ] Petersi nov. form.—Hoernes 1880: 126 (pars) [nomen nudum].

Columbella (Mitrella) Petersi nov. form.— Hoernes & Auinger 1880: 97 (pars), pl. 12, figs 5–6 [non Mitrella petersi Hilber, 1879 ].

Atilia (Macrurella) Petersi Hoernes et Auinger — Cossmann 1901: 245. [non Mitrella petersi Hilber, 1879 ].

Columbella (Mitrella) petersi R. Hö. — Boettger 1902: 17 [non Mitrella petersi Hilber, 1879 ].

Columbella (Mitrella) petersi Hö. Au. — Boettger 1906: 15 [non Mitrella petersi Hilber, 1879 ].

Mitrella petersi Hörn u. Auing.— Meznerics 1933: 340 [non Mitrella petersi Hilber, 1879 ].

M.[itrella]. (A [tilia].) petersi (R. Hörn. et Au.) — Sieber 1958a: 147 [non Mitrella petersi Hilber, 1879 ].

Mitrella (Atilia) petersi (R. Hörn. Au.) — Sieber 1958b: 148 [non Mitrella petersi Hilber, 1879 ].

Mitra bronni Mich. — Grković 1963: 120, pl. 1, fig. 6 [non Michelotti, 1847].

Type material. Holotype: NHMW 2020 /0162/0001, Steinebrunn, SL: 11.5 mm, MD: 3.1 mm, illustrated in Hoernes & Auinger (1880, pl. 12, figs 6a–c) as Columbella (Mitrella) Petersi , Figs 4C, 9A 1 –A 2 . Paratypes: NHMW1846 /0037/0157, SL: 11.4 mm, MD: 3.4 mm, Steinebrunn , illustrated in Hoernes & Auinger (1880, pl. 12, figs 5a–c) as Columbella (Mitrella) Petersi , Fig. 9D . NHMW 2020 /0162/0002, SL: 11.2 mm, MD: 3.1 mm, Steinebrunn ( Austria), Figs 9B 1 –B 2 . NHMW 2020 /0162/0003, SL: 12.8 mm, MD: 3.8 mm, Steinebrunn ( Austria), Figs 9C 1 –C 2 .

Additional material. NHMW1862 /0001/0373, 13 spec. Gainfarn ( Austria) . NHMW1871 /0011/0005, 270 spec., Steinebrunn ( Austria) . NHMW 1884 /0037/2898 (=A1553), 10 spec., Steinebrunn ( Austria) .

Type locality. Steinebrunn ( Austria), Vienna Basin .

Type stratum. Sandy silt of the Baden Formation.

Age. Middle Miocene, Badenian.

Etymology. Referring to the elongate slender shell.

Diagnosis. Mitrella species of moderately small size, very slender fusiform profile, high conical paucispiral protoconch, high, acute spire, and narrow aperture, with prominent denticles on thickened outer lip, D2 (second from top) stronger. Distinguished from other Paratethyan species by its extraordinarily elongate shape.

Description. Shell moderately small, very slender fusiform, with high spire, and narrowly incised suture. Protoconch paucispiral, high conical, of about two whorls. Teleoconch of nine whorls. Spire whorls high, flat-sided, with periphery at abapical suture. Last whorl high, moderately convex, rounded periphery, weakly contracting, high base. Aperture moderately narrow. Shell surface smooth, glossy; weak spiral cords on abapical portion of base and siphonal fasciole. Outer lip thickened with mid-labial callus pad; about eight prominent denticles, with D2 strongest. Anal canal shallow, U-shaped. Siphonal canal mid-length, narrow with shallow notch. Columella slightly twisted. Columellar callus not thickened, forming thin, narrow rim, weakly delimited from base. No columellar denticles. Parietal callus weakly developed.

Shell measurements and ratios. SL: 11.2–12.8 mm, MD: 3.1–3.8 mm, AA: 17–21°, SL/MD: 3.4–3.8, AL/AW: 3.8–4.3, LWH/AH: 1.2–1.4.

Discussion. Hoernes &Auinger (1880) confused this species with Mitrella petersi ( Hilber, 1879) .All subsequent authors followed the misidentifications by Hoernes & Auinger (1880). A comparison with the lectotype of Mitrella petersi reveals little similarity between the species. Mitrella petersi is much smaller, has a much wider apical angle, and a shorter spire. Moreover, it has a low conical protoconch, whereas the protoconch of M. elongatissima nov. sp. is turreted. For comparison with M. demaintenonae nov. sp., see above.

Mitrella liguloides Sacco, 1890 , from the Tortonian of Stazzano ( Italy), might represent a closely related species, but is twice the size. It has a very similar spire and an identical narrow aperture, but is slightly less slender, bears columellar denticles and has a deeply-incised siphonal notch (see Sacco 1890; Ferrero Mortara et al. 1981, pl. 58, figs 13a–b). Mitrella teres ( Bellardi, 1848) , from the Pliocene of Italy, is reminiscent of M. elongatissima in its high and slender spire, but differs in its convex whorls, higher last whorl, and longer siphonal canal (see Ferrero Mortara et al. 1981, pl. 57, figs 7a–b; Chirli 2002, pl. 6, figs 7–12).

Palaeoenvironment. The frequent occurrence at Steinebrunn suggests shallow, inner neritic environments with sea grass (own data).

Distribution in Central Paratethys. Badenian (middle Miocene): Vienna Basin: Gainfarn, Steinebrunn ( Austria) ( Sieber 1958b; own data); southern Pannonian Basin: Tešanj ( Bosnia-Herzegovina) ( Grković 1963).

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.

FIGURE 9 A1–A2. Mitrella elongatissima nov. sp., NHMW 2020/0162/0001, holotype, Steinebrunn (Austria). B1–B2. Mitrella elongatissima nov. sp., NHMW 2020/0162/0002, paratype, Steinebrunn (Austria). C1–C2. Mitrella elongatissima nov. sp., NHMW 2020/0162/0003, paratype, Steinebrunn (Austria). D. Mitrella elongatissima nov. sp., NHMW1846/0037/0157, paratype, Steinebrunn (Austria). E1–E2. Mitrella demaintenonae nov. sp., NHMW1878/0001/0081, paratype, Möllersdorf; F1–F2. Mitrella demaintenonae nov. sp., NHMW2020/0162/0002, Coşteiu de Sus (Romania). G1–G2. Mitrella demaintenonae nov. sp., NHMW 2020/0161/0001, holotype, Coşteiu de Sus (Romania). H. Mitrella demaintenonae nov. sp., NHMW1867/ 0019/0049b, Coşteiu de Sus (Romania).