Paragattendorfia patens (Vöhringer, 1960)

Figs 20–21; Tables 10–11

Imitoceras patens Vöhringer, 1960: 147, pl. 1 fig. 1, text-fig. 24.

Paragattendorfia patens – Korn 1994: 36, text-figs 31c–d, 32d, 63c; 2006: text-fig. 3g. — Sprey 2002: 52, text-fig. 17d. — Kullmann 2009: text-fig. 2.4.

Diagnosis

Species of Paragattendorfia with a conch reaching 40 mm diameter. Conch at 20 mm dm thickly pachyconic, subinvolute to subevolute (ww/dm ~0.75; uw/dm ~0.30). Whorl profile at 20 mm dm strongly depressed (ww/wh ~2.00); coiling rate very low (WER ~1.45).Venter broadly rounded, umbilical margin rounded. Growth lines fine, narrow-standing, with nearly linear course. Without constrictions on the shell surface; with linear internal shell thickenings. Suture line with narrowly V-shaped external lobe and narrowly V-shaped adventive lobe.

Material examined

Holotype

GERMANY • Rhenish Mountains, Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 2; Vöhringer Coll.; illustrated by Vöhringer (1960: pl. 1 fig. 1), Korn (1994: text-fig. 31c) and Korn (2006: text-fig. 3g); re-illustrated here in Fig. 20A; GPIT-PV- 63912.

Paratypes

GERMANY • 2 specimens; Rhenish Mountains, Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 2; Vöhringer Coll.; GPIT-PV- 63914, GPIT-PV- 63916.

Additional material

GERMANY • 1 specimen; Rhenish Mountains, Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 3a; Korn 1991 Coll.; MB.C. 31066 • 1 specimen; Rhenish Mountains, Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 3d2; Weyer 1993–1994 Coll.; MB.C. 31067.

Description

Holotype GPIT-PV-63912 is a moderately preserved, partly mechanically ground specimen with 22 mm conch diameter (Fig. 20A). It is thickly pachyconic and subinvolute (ww/dm = 0.73; uw/dm = 0.29) with a very low coiling rate (WER = 1.45). The whorl profile is crescent-shaped with a narrowly rounded umbilical margin. The suture line has a V-shaped external lobe and a symmetrical adventive lobe of almost the same shape, but it is slightly deeper. Both lobes are separated by a symmetrical, narrowly rounded ventrolateral saddle (Fig. 21B).

Remarks

Paragattendorfia patens is separated from P. sphaeroides by the more slender conch (ww/dm = 0.85 in P. patens but above 1.00 in P. sphaeroides at 10 mm dm) and in the wider umbilicus (uw/dm = 0.30 in P. patens but 0.20 in P. sphaeroides at 10 mm dm).

The species is rather rare in the Hangenberg Limestone. A record of “ Paragattendorfia aff. patens ” from the Montagne Noire by Becker & Weyer (2004) does not belong here; the specimen possesses a dorsal siphuncle and must be attributed to Wocklumeria . It was a Late Devonian contamination in an earliest Carboniferous assemblage (Korn 2005).