Galeodinopsis germanica, Garilli & Parrinello, 2014

Garilli, Vittorio & Parrinello, Daniela, 2014, Taxonomy and palaeobiogeography of the Cenozoic Euro-Mediterranean rissoid gastropod Galeodinopsis and its relationship with close genera, Acta Palaeontologica Polonica 59 (2), pp. 379-406 : 391-393

Galeodinopsis germanica sp. nov.

Fig. 11.

1960 Alvania (Alvinia) multicostata ( Speyer, 1864) ; Anderson 1960: 24, pl. 3: 1.

1978 Alvania (Arsenia) semperi Wiechmann, 1871 ; Janssen 1978a: pl. 11: 31.

Etymology: From Latin germanicus, German.

Type material: The holotype ( SMF 335576 ), represented by a presumably fully grown shell preserving protoconch and provided with two varices on the last whorl, and 6 paratypes ( SMF 336787 , 336788 , 336789 , 336790 , 336791 a, 336791b), originally labelled as “ Alvania semperi Wiechmann ” .

Type locality: Abandoned mine-pit Höllkopf , Glimmerode, south of Hessisch-Lichtenau, Hessen, Germany .

Type horizon: Early Chattian (Late Oligocene) Kasseler Meeressand.

Material.— Type material only.

Diagnosis.—Shell small, conical-ovate. Protoconch multispiral with up to 2.5 rounded whorls. Protoconch 1 with netted sculpture; protoconch 2 sculptured with fine lirae and axial segments between lirae. Teleoconch with up to 3.3 convex whorls sculptured with axial and spiral elements forming a clathrate pattern. Axial ribs slightly curved, prevailing over spirals in most specimens. Microsculpture characterized by Manzonia -like pattern, with numerous lines of pits on spiral cords. Last whorl well expanded, with one or two varices. Aperture wide, ovate, with double-rimmed outer lip. Inner lip curved, forming very small umbilical chink.

Description.—Shell small, conical-ovate, reaching 2.6 mm in height and 1.5 in width; average Ht/W of 1.65, about 1.7 in shells higher than 2 mm. Protoconch multispiral, conical, with 2.2 to 2.5 rounded whorls, nucleus rather immersed. Protoconch 1 of about 0.7 whorls with netted sculpture consisting of 5–6 very thin spiral lirae and numerous, irregular, short, very narrow axial segments in interspaces. Early protoconch 2 sculptured with 2 more-or-less discontinuous fine spiral threads in subcentral and abapical position, and very narrow, opisthocline plicae in subsutural position. Close to protoconch/teleoconch boundary only one irregular, strongly discontinuous thread formed by merged microscopic dots. Protoconch/teleoconch boundary well marked by thin, sinuous lip. Teleoconch with up to 3.3 evenly convex whorls sculptured with axial and spiral elements, forming clathrate pattern. Axial ribs slightly curved, more-or-less markedly opisthocline, more prominent than spirals; 17–22 on penultimate whorl; lacking on shell base. Spiral sculpture of almost flat cords overriding axial ribs; 4 cords close to protoconch/ teleoconch boundary, rapidly increasing to 5–6; 6–7 on penultimate whorl of shells with height over 2 mm; 11–14 on last whorl, of which 5–7 on base. Subsutural and suprasutural cords usually weaker and/or discontinuous. Microsculpture on main spiral cords of flat ridges delimited by at least 7 spiral alignments of microscopic, subcircular pores forming pitted pattern. Pores formed by extremely short axial elements in very narrow interspaces between ridges. Narrow, raised spiral ridges cover interspaces between primary spiral sculpture, formed by discontinuous, tooth-like elements, extending perpendicularly from shell surface. Microsculpture of subsutural cord lacking pitted pattern, consisting of weakly raised spiral ridges with flat centres. Last whorl well expanded, making up 0.6 to 0.72 of total shell height; some shells with one or two varices forming angles of about 100°, 180°, 250°, and 340° to plain of peristome. Aperture wide, ovate, very rounded anteriorly, with acute angle posteriorly, making up 0.4–0.5 and about 0.6–0.75 of total shell and last whorl height, respectively. Outer lip double-rimmed, slightly sinuous, weakly opisthocline, internally smooth, externally with varicose swelling covered by incremental scars and spiral sculpture. Inner lip curved, weakly expanded in columellar area, forming very narrow to obsolete umbilical chink.

Remarks.— Galeodinopsis germanica sp. nov. is easily separable from other congeners by its slender shell shape resembling some Manzonia species, with which it shares the microsculptural pattern and the sculpture with axial elements more prominent than spirals. The most similar Manzonia species is M. foraminata ( Lozouet, 1998) , from the French Late Oligocene (Chattian) of the Aquitaine Basin. There are, however, significant differences allowing separation between G. germanica sp. nov. and Manzonia species: the occurrence in G. germanica sp. nov. of 1 or 2 varices on the last whorl, the absence of strongly raised cords on the shell base and the less rounded and proportionally larger aperture. These are typical Galeodinopsis characters. G. germanica sp. nov. is comparable with weakly sculptured morphs of G. semperi (hereafter described), from which it differs mainly by having different sculpture, consisting of more prominent, markedly curved ribs. G. germanica sp. nov. can also be distinguished by its more rounded teleoconch whorl profile (lacking the characteristic marked subsutural ramp of G. semperi ) and by the typical pitted microsculptural pattern, as in the Galeodinopsis type species, G. tiberiana (compare Figs. 2C 1 and 11D 4). Also it bears more spiral cords: 6–7 vs. 3–5 and 11–14 vs. 7–10 on the penultimate and last whorl, respectively. The shells illustrated by Anderson (1960: pl. 3: 1, as Alvania multicostata ) and Janssen (1978a: pl. 11: 31, as Alvania semperi ) possibly are G. germanica nov. sp., having convex, rounded whorls, with no or obsolete subsutural ramp, and provided with axial elements more prominent than spirals. Due to this confusion, most of the Oligocene occurrences/material reported by these authors as “ A. multicostata ”/” A. semperi ” possibly include both G. germanica nov. sp and G. semperi (see the next section for description of this species). Unfortunately, we were unable to study this material.

Galeodinopsis germanica sp. nov. shows a sculptural pattern of protoconch 2 very similar to that observed in other Galeodinospis species, except for the occurrence of subsutural plicae (Fig. 11C 3 –C 5). It is remarkable that the microsculpture of the very weak subsutural cords (Fig. 11D 5) is similar to the microsculptural pattern seen in G. biangulata , G. semperi and other species related to Alvinia .

Stratigraphic and geographic range.—Chattian of central Germany, at Glimmerode (type locality) and Freden ( Anderson 1960, as Alvania muticostata ), and of western Germany, at Moers ( Janssen 1978a, as Alvania semperi ).

Figures

Fig. 2. Rissoid gastropod Galeodinopsis tiberiana (Coppi, 1876), type species of Galeodinopsis Sacco, 1895 from Rio Grizzaga sands, Gagliardella, Fogliano, Maranello, Modena, N Italy, type locality, Piacenzian, Pliocene. A. Specimen ex MF, MZPD Mal 2035a, in apertural view. B. Specimen ex MF, MZPD Mal 2035b, in dorsal view. C. Specimen ex MF, MZPD Mal 2035c showing typical Manzonia-like teleoconch microsculpture (C 1) and detail of protoconch 1 with netted sculpture (C 2). Black arrows indicate the protoconch 1/protoconch 2 boundary. Scale bars: A, B, 1 mm; C, 20 μm.

Fig. 1. Location of the study sites in the Euro-Mediterranean area. Open circles, studied from bibliographic sources; shaded circles, studied from museum/private collections.