Clinurella sophiae Boettger, 1902

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 : 40-42

Clinurella sophiae Boettger, 1902 nov. comb.

Figs 13G 1 –G 2

* Columbella (Mitrella) sophiae n. sp. — Boettger 1902: 17.

Columbella (Mitrella) sophiae Bttgr. — Boettger 1906: 17.

Pyrene (Mitrella) sophiae (Boettger) — Zilch 1934: 253, pl. 16, figs 88a–b.

Type material. Lectotype (designated by Zilch 1934): SMF 360681 (= XII.2222 a), Senckenberg Museum, Frankfurt/Main, Germany, SL: 16.7 mm, MD: 7.5 mm, Coşteiu de Sus ( Romania), illustrated in Zilch (1934, pl. 16, figs 88a–b), Figs 13G 1 –G 2 . Paralectotypes: XII.2222 a–b, Senckenberg Museum, Frankfurt/Main, Germany, Coşteiu de Sus ( Romania).

Description. Shell medium sized, solid, moderately broad, with broad spire and narrowly incised suture. Protoconch unknown. Early teleoconch missing in available specimen. Spire whorls broad, weakly convex, periphery at abapical suture. Last whorl regularly convex, strongly constricted at base. Aperture very wide in central part due to flaring outer lip. Anal canal weakly developed, broad V-shaped. Siphonal canal long, very narrow, distinctly deflected. On last quarter whorl (i.e., the dorsal aspect of outer lip) weak spirals appear below mid-whorl, strengthening abapically, becoming strong cords on the base and siphonal fasciole. Columellar callus thickened, sharply delimited, forming broad rim, detached from base, with six prominent columellar denticles. Parietal callus thickened, adherent. Outer lip strongly thickened in central part with six stout denticles within.

Shell measurements and ratios. SL: 16.7 mm, MD: 7.5 mm, AA: 39°, SL/MD: 2.4, AL/AW: 3.2, LWH/AH: 1.3.

Discussion. This species is unique within the Paratethyan Columbellidae . Clinurella albucianensis Sacco, 1890 , from the Langhian of Albugnano (Colli Torinesi, Italy) is quite similar and might be a subjective senior synonym. Based on the illustration in Sacco (1890b: 45, pl. 2, figs 51a–b), the Italian shell differs mainly in its shorter siphonal canal. Unfortunately, the holotype of C. albucianensis is a fragmentary specimen, which was not listed by Ferrero Mortara et al. (1981). Clinurella scalaris Sacco 1890 , from the Burdigalian of Pino Torinesi has an identical flaring outer lip, but differs in its higher and more slender spire (see Ferrero Mortara et al. 1981, pl. 58, figs 4–5).

Palaeoenvironment. Unknown, probably offshore.

Distribution in Central Paratethys. Badenian (middle Miocene): Făget Basin: Coşteiu de Sus ( Romania) ( Boettger 1906).

Genus Defensina nov. gen.

Type species. Columbella (Mitrella) bucciniformis Hoernes & Auinger, 1880 , Middle Miocene , Romania .

Etymology. From Latin defensionis (= defense), referring to the apertural features.

Diagnosis. Moderately small shell with high conical spire and short globose to subcylindrical last whorl, with weak dorsal gibbosity and rapidly contracting base. Aperture small, adapical tip distinctly below periphery of last whorl, wide, ovoid with regularly concave columella and thickened and twisted terminal columellar callus. Outer lip with thickened callus pad, bearing three wide spaced elongate denticles.

Description. Shell moderately small, moderately broad, with high conical spire and short globose to subcylindrical last whorl with weak dorsal gibbosity. Protoconch low conical, paucispiral of less than two convex whorls, smooth. Transition into teleoconch indistinct. Teleoconch of nine whorls; spire whorls weakly convex, low with narrowly incised suture. Penultimate whorl with slightly allometric growth, increasing in width, with periphery slightly above abapical suture. Last whorl globose to subcylindrical, narrower than penultimate whorl with weak dorsal gibbosity and rapidly contracting base; suture descending below periphery. Shell surface smooth except for densely spaced delicate spiral cords on base and siphonal fasciole. Aperture small, ovoid. Adapical tip of aperture below periphery of last whorl. Outer lip bearing thickened internal labial callus pad; three prominent, wide spaced elongate denticles within; D1 slightly below anal canal, D3 delimiting lateral edge of siphonal canal, D1 and D3 extending to apertural edge; lip edge between D1 and D3 slightly concave; D2 placed in centre of concavity less prominent, not extending to apertural margin. Anal canal sharply incised, narrow V-shaped. Siphonal canal short, moderately wide. Columella broadly excavated, with strongly thickened abapical termination delimiting medial edge of siphonal fasciole. Columellar callus forming thickened, sharply-delimited callus rim.

Stratigraphic and geographic range. Middle Miocene (Badenian, Langhian), Central Paratethys Sea.

Included species. Only the type species is known.

Palaeoenvironment. Unknown, probably middle to outer neritic environments.

Discussion. Defensina is unique in the circum-Mediterranean Neogene Columbellidae and differs from all other genera in its weak dorsal hump and the peculiar aperture with only three prominent denticles on the callused outer lip and the very thickened columellar ridge bordering the siphonal canal. Moreover, the columella of all other Paratethyan columbellids is narrowly excavated in the upper third to upper half, which results in an angulation to the columella, whereas in Defensina the columella is broadly and evenly excavated, resulting in an evenly concave columella.

Defensina is somewhat reminiscent of Dorsina Jung, 1989 in its high spire, dorsal hump, smooth shell and callused aperture; e.g. Dorsina gibberula (G.B. Sowerby I, 1832) , D. melajoensis ( Jung, 1969) (see Jung 1989). However, any similarity is superficial, as the apertural characters are quite different from those seen in members of the ‘ Strombina group’. The same features allow separation from Sincola Olsson & Harbison, 1953 (type species Strombina sincola Olsson, 1922 , Miocene, Costa Rica) and Strombina Mörch, 1852 (type species Columbella lanceolata G.B. Sowerby I, 1832 , present-day, Panamic Pacific), which both have axial ribs and apertural dentition typical to the ‘ Strombina group’.

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.

FIGURE13A1–A2.OrthurellaconvexulaSacco,1904,NHMW1937/0002/0277,BadVöslau(Austria).B1–B2.Orthurellaconvexula Sacco, 1904, NHMW1846/0037/0271, Baden (Austria). C1–C2. Orthurella convexula Sacco, 1904, NHMW1856/0024/0013, Lăpugiu de Sus (Romania). D1–D2. Orthurella moravica (Hoernes & Auinger, 1880), NHMW1861/0011/0519a, paralectotype, Jaroměřice nad Rokytnou (the Czech Republic). E1–E2. Orthurella moravica (Hoernes & Auinger, 1880), NHMW1861/0011/ 0519b, lectotype, Jaroměřice nad Rokytnou (the Czech Republic). F1–F2. Orthurella moravica (Hoernes & Auinger, 1880), NHMW2020/0159/0001, paralectotype, Jaroměřice nad Rokytnou (the Czech Republic), G1–G2. Clinurella sophiae Boettger, 1902, SMF 360681, lectotype, Coşteiu de Sus (Romania). H1–H2. Orthurella convexula Sacco, 1904, NHMW1858/0043/0017, Lăpugiu de Sus (Romania). I. Orthurella moravica (Hoernes & Auinger, 1880), NHMW2020/0159/0002, paralectotype, Jaroměřice nad Rokytnou (the Czech Republic).