Galeodinopsis biangulata ( Deshayes, 1864 )

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 : 388-391

Galeodinopsis biangulata ( Deshayes, 1864)

Figs. 9, 10.

1863 Rissoa Duboisii Nyst ; Sandberger 1863: 131–132, pl. 10: 10–10a, as Rissoa succincta Nyst in pl. 10 (lapsus calami).

1864 Rissoa biangulata nov. sp.; Deshayes 1864: 407–408, pl. 24: 29–30 (figures in separate volume, 1866).

1867 Rissoa Duboisii Nyst ; Koenen 1867: 113.

1921 Manzonia (Taramellia) areolifera Sandberger ; Cossmann 1921: 31, pl. 2: 11, 12.

1960 Alvania (Taramellia) duboisi (Nyst, 1843) ; Anderson 1960: 25, pl. 3: 3.

1985 Manzonia (Manzonia) duboisi (Nyst, 1843) ; Ponder 1985: 48, fig. 100C.

2008 Galeodinopsis duboisi (Nyst, 1843) ; Garilli 2008: figs. 100–103.

2011 Taramellia duboisi ( Nyst, 1845) ; Müller 2011: 24–25, pl. 5: 22a, b.

Type material: One possible syntype in UCBL provided with original label by Deshayes ( Fig. 10A, B ), with catalogue number EM 31000 .

Type locality: Deshayes (1864: 407) reported Jeure, Montmorency,

Versailles (Paris Basin, France) and Weinheim (Mainz Basin, Germany). This last locality is with reference to the material published in Sandberger (1863: 131, pl. 10: 10–10a).

Type horizon: Deshayes (1864: 407) reported “Sables supérieurs” (upper sands), from the Paris Basin, which are Early Rupelian in age.

Material studied. —10 shells in MNHU, MB.Ga.7744, as Rissoa duboisi Nyst, Waldböckelheim, Rheinland-Pfalz, W Germany, middle Oligocene marine sand; 5 shells, MZPD Mal 2036, originally in MF, FE 15A, in two separate lots as Alvania duboisi and Manzonia duboisi , Hessen, SE of Kassel, Hessisch-Lichtenau, Glimmerode, central Germany, Late Oligocene (Chattian); 28 shells in UCBL, Deshayes coll. (one of them with original label), Tertiary of the Paris Basin, France; 10 shells in UCBL, Paris Basin coll., Brunehaut, France; 18 shells, in UCBL, Paris Basin coll., Jeures, France.

Description. —Shell small, conical-ovate to conical-turrited, reaching 4.95 mm in height and 3.15 mm in width; Ht/W quite variable, also depending on occurrence and position of varices on last whorl, from 1.4 to 2 in shells over 3 mm in height, average value 1.62. Protoconch multispiral, conical with 2.2 to 2.3 rounded whorls and a rather immersed nucleus. Protoconch 1 of about 0.7 whorls with netted sculpture consisting of 6–7 very thin spiral lirae and numerous, irregular, short, very narrow axial segments occurring in interspaces between lirae. Protoconch 2 sculptured with microscopic dots roughly forming one adapical and two abapical discontinuous fine spiral threads, particularly next to protoconch/teleoconch boundary. Protoconch/teleoconch boundary well-marked by thin, sinuous lip. Teleoconch with up to 4.5 convex whorls. Whorls sculptured with axial and spiral elements forming more-or-less strong clathrate, almost bicarinate pattern and acute knobs at their intersections. Axial ribs slightly curved, opisthocline to almost straight, most more prominent than spirals; 13–16 (rarely 17–18) on the penultimate whorl; lacking on shell base. Main spiral sculpture of cords overriding axial ribs; 2 on early and penultimate whorls; 6–8 and 3–6 on last whorl and on shell base, respectively. A very weak to obsolete subsutural cord occurs next to suture in some specimens. Teleoconch microsculpture on spiral cords of fine, rather flat, closely spaced spiral threads, joined by very low, short axial elements in a few specimens. Last whorl well expanded, making up 0.6 to 0.75 of total shell height, some shells bearing one varix at angles of 65° to 340°. Aperture wide, ovate, very rounded anteriorly, with acute angle posteriorly, making up about 0.4–0.55 and about 0.6–0.75 of total shell and of last whorl height, respectively. Outer lip sinuous, weakly opisthocline, double-rimmed; internally smooth, with thin rim on its edge; externally with

Fig. 9. Rissoid gastropod Galeodinopsis biangulata ( Deshayes, 1864) from Glimmerode, Hessisch-Lichtenau, SE of Kassel, Hessen, Late Oligocene, → Chattian (A–E), Waldböckelheim, Rheinland-Pfalz, Rupelian sands (F). A. Specimen ex MF, MZPD Mal 2036a, in apertural view (A 1); detail of a subsutural cord (A 2). B. Specimen ex MF, MZPD Mal 2036b, in profile view (B 1), teleoconch microscultpure (B 2). C. Specimen ex MF, MZPD Mal 2036c, in dorsal view (C

1

); detail of protoconch showing traces of the netted sculpture on protoconch 1 (C

2

); protoconch in dorsal view (C

3

), black arrows indicate the protoconch/teleoconch boundary. D. Slender specimen ex MF, MZPD Mal 2036d in apertural view. E. Specimen ex MF, MZPD Mal 2036e with strong sculpture, in apertural view. F. Slender specimen MNHU MB.Ga.7744 with weaker sculpture resembling Manzonia areolifera sensu Cossmann (1921) ,

in apertural (F

1

) and dorsal (F

2

) views. Scale bars: D–F, 1 mm; A1, B1, C1, 500 μm; C3 200 μm; C2, 50 μm; A2, B2, 20 μm.

very marked varicose swelling. Inner lip curved, weakly expanded in columellar part, forming very narrow to obsolete umbilical chink.

Remarks. —Often misidentified as Rissoa duboisii Nyst, 1845 , above all because of the low-quality original illustration and the inadequate description by Nyst (1845: pl. 37: 19), Galeodinopsis biangulata is characterized by having 2 spiral cords on all teleoconch whorls with the exception of the last. It shows marked variability in Ht/W ratio and in the robustness of spiral and axial elements. The morph with delicate sculpture (Figs. 9F and 10E) matches that illustrated by Cossmann (1921: pl. 2: 11, 12) as “ Manzonia (Taramellia) areolifera (Sandb.) ”, a determination probably due to a lapsus calami in Sandberger (1863). Actually, Rissoa areolifera Sandberger, 1863 is a quite different species attributed to Alvania , as shown by material from the type locality (catalogue number MB.Ga.7749 at MNHU) matching the original illustration in Sandberger (1863: pl. 10: 11–11a as “ Rissoa Duboisi ”, lapsus calami). In fact, this species is represented by conical shells lacking varices, and with a smaller aperture without a double-rimmed outer lip (see Fig. 7A, B ).

The type specimen illustrated by Deshayes (1866: pl. 24: 29, 30) was not found in his coll. from the Paris Basin at UCBL. However, indisputable conspecific specimens in the same institution are in this and other colls. from the same geological formation. Among them one specimen (EM 31000) with an original label from Deshayes ( Fig. 10A, B ) could be regarded as a syntype. It has all of the main characterizing characters as illustrated by Deshayes (1866: pl. 24: 30). Another specimen from the same collection ( Fig. 10E ) matches well that illustrated by the same author (Deshayes 1866: pl. 24: 29). Conspecific shells ( Fig. 10C ) in UCBL, from “Jeures”, near Fontenay (Paris Basin coll.), could be regarded as topotype material as this locality is the same as cited in the original description (“Jeure”, see Deshayes 1864: 407). This locality is also known as “Jeurre” ( Harris and Burrows 1891).

The microsculpture of Galeodinopsis biangulata is different from that shown by the type species (see below), having a sort of pseudopitted pattern. This consists of fine, rather flat, closely spaced threads covering the main spiral cords (Fig. 9B 2). The pseudopitted character is due to the very obsolete or absent narrow axial bridge that form the typical pitted surface in Manzonia . Other very narrow, raised spiral threads are present in the interspaces between the main spiral cords and on the subsutural one (Fig. 9A 2). Comparable microsculpture occurs in G. semperi ( Wiechmann, 1871) (see the section dedicated to this species) and in rissoid species linked to Alvinia , such as Turbo zetlandicus ( Fig. 5A ), with which G. biangulata shares the turrited-shouldered shell shape. However, a relevant combination of characters justifies the placement of this species within Galeodinopsis : the ornamentation of the protoconch, particularly the netted protoconch 1 (Fig. 9C 2), the common occurrence of varices on the last whorl, the large aperture with a double-rimmed outer lip, and the quite inflated last whorl. Therefore, the placement in Taramellia Seguenza, 1903 ( Müller 2011 as T. duboisi ) also should not be accepted, as this genus is a synonym of Alvinia ( Ponder 1985) .

Stratigraphic and geographic range. —Late Eocene/very Early Oligocene at Latdorf (Latdorfian Stage) and Magderburg, central Germany ( Koenen 1867, as Rissoa Duboisii ; Müller 2011, as Taramellia duboisi ); Rupelian of northern France (Paris Basin) and western Germany (Mainzer Basin), at Waldböckelheim; Chattian of central, at Glimmerode, and north-central Germany, at Söllingen ( Koenen 1867).

Figures

Fig. 10. Rissoid gastropod Galeodinopsis biangulata (Deshayes, 1864) from the Oligocene of the Paris Basin. A. Possible syntype specimen UCBL EM 31000, Deshayes collection, in profile view, resembling Deshayes’ illustration (1866: pl. 24: 30). B. Original label of the same specimen. C. Specimen UCBL, EM 30996, Paris Basin collection from Jeures, in apertural view. D. Specimen UCBL, EM 30997, Deshayes collection, in profile view (D1); protoconch in profile view (D2), white arrows indicate the protoconch/teleoconch boundary; detail of protoconch showing trace of the netted sculpture on protoconch 1 (D3), white arrow indicates the protoconch 1/protoconch 2 boundary. E. Specimen UCBL, EM 30998, Deshayes collection, in apertural view, matching Deshayes’ illustration (1866: pl. 24: 29) and resembling Manzonia areolifera sensu Cossmann (1921). F. Specimen UCBL, EM 30999, Deshayes collection, in apertural view. Scale bars: A, C, D1, E, F, 1 mm; D2, 100 μm; D3, 30 μm.

Fig. 7. Rissoid gastropods Alvania areolifera (Sandberger, 1863) (A, B) and Alvania punctura (Montagu, 1803), type species of Arsenia Monterosato, 1891 (C–E). A. Specimen MNHU MB.Ga.7749.1, Waldböckelheim, Rheinland-Pfalz, W Germany, Rupelian, Oligocene, in apertural view. B. Specimen MNHU MB.Ga.7749.2, same site as in A, in dorsal view. C. Slender specimen ex VG, MZB 49971, Recent, station CS’96/54, 135 m deep, Graham Bank, Strait of Sicily, in dorsal view (C 1), protoconch (C 2), sculpture of protoconch 1 (C 3), detail of teleoconch microsculpture (C 4). D. Specimen ex VG, MZPD Mal 2044a, Sicilian, Early Pleistocene, Acqua dei Corsari, Ficarazzi, Palermo, NW Sicily, in apertural view. E. Specimen ex VG, MZPD Mal 2044b, with inflated last whorl, same site as in D, in dorsal view. Scale bars: A, B, C , D, 1 mm; E, 500 μm; C , 100 μm; C , C , 25 μm.

Fig. 5. Teleoconch microsculpture in the type species of rissoid gastropods Alvinia Monterosato, 1884 and Flemellia Nordsieck, 1972. A. Alvinia zetlandica Montagu, 1815), type species of Flemellia, ex MF, MZPD Mal 2046a (same specimen as in Fig. 4C), Calabrian, Early Pleistocene of Lazzaro, Vallone Catrica, Reggio Calabria, S Italy, showing closely spaced spiral threads on shell surface at different magnifications. B. Alvinia weinkauffi (Weinkauff, 1868 ex Schwartz von Mohrenstern ms), type species of Alvinia, ex VG, MZPD Mal 2048 (same specimen as in Fig. 4B), Recent, infralittoral bottom (37 m deep) off Formica Island, W Sicily, showing narrow spiral threads on shell surface at different magnifications. Scale bars: A , B , 50 μm; A , B , 10 μm.