Mitrella convexa Friedberg, 1911

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

Mitrella convexa Friedberg, 1911

Figs 7C 1 –C 2

* Columbella curta var. convexa mihi— Friedberg 1911: 35, pl. 2, fig. 2.

Columbella (Alia) curta convexa (Fbg.) — Sieber 1953: 187.

Pyrene (Alia) curta convexa Friedb. — Strausz 1954: 105, pl. 4, fig. 82.

C.[olumbella]. (A [lia].) curta convexa (Fbg.) .— Sieber 1958a: 148.

Columbella (Alia) curta convexa Friedberg — Švagrovský 1960: 100, pl. 9, fig. 8.

Columbella ( Mitrella ?) convexa Friedberg, 1912 — Strausz 1966: 289, pl. 42, figs 29–30.

Columbella (Alia) curta convexa Friedberg — Atanacković 1969: 207, pl. 11, figs 6–6a.

Columbella (Alia) curta ( Dujardin 1837) — Atanacković 1985; 145, pl. 33, figs 3–4 [non Dujardin, 1837].

non Columbella (Alia) curta var. convexa Friedberg 1911 —Kojumdgieva in Kojumdgieva & Strachimirov 1960: 182, pl. 45, fig.

3 [= Graphicomassa korytnicensis ( Bałuk, 1995) ].

Type material. Holotype stored in the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv (formerly Muzeum Dzieduszyckich), illustrated in Friedberg (1911: 35, pl. 2, fig. 2, Figs 7C 1 –C 2 ). Unfortunately, it was not possible to obtain photos of the holotype.

Description. Medium sized, robust, broad, elongate ovoid shell with incised suture and moderately high, broad, weakly cyrtoconoid spire. Protoconch unknown. Teleoconch of seven whorls. Spire whorls weakly convex with periphery at abapical suture. Last whorl high, weakly convex, moderately constricted. Aperture elongate, moderately narrow. Columellar callus forming broad rim, detached from base. Parietal callus weak. Outer lip thickened, denticulate with about nine prominent denticles. Anal canal weakly incised, V-shaped. Siphonal canal short, wide. Shell surface smooth except for few weak spiral cords on base

Shell measurements and ratios. SL: 16 mm, MD: 7 mm, AA: 50°, SL/MD: 2.3, AL/AW: 3.9, LWH/AH: 1.4.

Discussion. This species is based on a single specimen from Korytnica. At first sight it might be mistaken for an atypical morph of the syntopic Graphicomassa korytnicensis ( Bałuk, 1995) . Mitrella convexa , however, lacks the thickened parietal callus and the centrally thickened outer lip, which are typical for G. korytnicensis . Moreover, its outer lip is convex and lacks the straight margin of Graphicomassa species. Mitrella convexa is reminiscent of M. viennensis nov. sp. in its apertural features but differs in its much lower spire. Mitrella isseli Sacco, 1890 , from the Tortonian of Italy, is a morphologically similar species, which differs in its less convex spire whorls and the broader columellar callus (see Sacco 1890b; Ferrero Mortara et al. 1981, pl. 56, figs 7a–b).

Palaeoenvironment. Unknown.

Distribution in Central Paratethys. Badenian (middle Miocene): Carpathian Foredeep: Korytnica ( Friedberg, 1911); Pannonian Basin: Várpalota ( Hungary) ( Strausz 1954, 1966); southern Pannonian Basin: Stanišljeviši, Milijevići ( Bosnia and Hercegovina) ( Atanacković 1969).

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 7. Species described by Friedberg (1911, 1938). A1–A2. “Columbella” paucicostata (Friedberg, 1911), ZNG PAN 1257, holotype, Dryszczów (Ukraine).B1–B2. Sulcomitrella januskiewiczi (Friedberg, 1938), ZNG PAN 2528, lectotype, Zborów (Ukraine). C2–C2. Mitrella convexa Friedberg, 1911, re-illustrated from Friedberg (1911, pl. 2, fig. 2).