Voehringerites peracutus ( Vöhringer, 1960 )

Korn, Dieter & Weyer, Dieter, 2023, The ammonoids from the Gattendorfia Limestone of Oberrödinghausen (Early Carboniferous; Rhenish Mountains, Germany), European Journal of Taxonomy 882, pp. 1-230 : 111-113

Voehringerites peracutus ( Vöhringer, 1960)

Figs 66–67 ; Tables 64–65

Karagandoceras peracutum Vöhringer, 1960: 166 , pl. 1 fig. 3, text-fig. 43.

Voehringerites peracutum – Manger 1971: 36, pl. 12 figs 4, 7, text-figs 3a, 4.

Voehringerites peracutus – Weyer 1972: 345. — Bartzsch & Weyer 1988a: 138. — Korn 1994: 65, text-figs 31f–g, 63a, 71b. — Korn & Weyer 2003: 99, text-figs 14k, 15. — Sprey 2002: 53, text-fig. 18b. — Becker & Weyer 2004: 20, text-figs 4f, 10–13.

non Voehringerites peracutus – Korn 1981: 524, text-fig. 5.

Diagnosis

Species of Voehringerites with a conch reaching 60 mm diameter. Conch thickly discoidal, subinvolute at 5 mm dm (ww/dm ~0.55; uw/dm ~0.20); extremely discoidal, involute at 15 mm dm (ww/dm ~0.32; uw/dm ~0.05); extremely discoidal, involute at 25 mm dm (ww/dm ~0.28; uw/dm = 0.00). Whorl profile at 30 mm dm strongly compressed (ww/wh ~0.45); coiling rate high (WER ~2.15). Venter broadly rounded in the early stage, galeate in the subadult stage and sharply acute in the adult stage. Growth lines fine with weakly biconvex course. Without constrictions on the shell surface; without internal shell thickenings.

Material examined

Holotype

GERMANY • Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 5 ; Vöhringer Coll.; illustrated by Vöhringer (1960: text-fig. 43), Manger (1971: text-fig. 4) and Korn (1994: text-fig. 31f); re-illustrated here in Fig. 66A ; GPIT-PV-63958.

Paratype

GERMANY • Rhenish Mountains , Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 5; Vöhringer Coll.; GPIT-PV-63966 .

Additional material

GERMANY • 14 specimens; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 5a2 ; Weyer 1993–1994 Coll.; MB.C.3723.1, MB.C.3723.2, MB.C.3724.3-14 • 3 specimens; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 5b ; Weyer 1993–1994 Coll.; MB.C.3724.1, MB.C.3724.2, MB.C.31145 • 3 specimens; Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 5c ; Weyer 1993–1994Coll.; MB.C.3725, MB.C.31146.1–2 • 1 specimen; Rhenish Mountains, Hasselbachtal ; Hangenberg Limestone , bed 72 ; Weyer 1993–1994 Coll.; MB.C.5245.1.

Description

Both the holotype GPIT-PV-63958 ( Fig. 66A ) and the paratype GPIT-PV-63966 ( Fig. 66B ) are fragments that reveal little more than that they belong to an extremely discoidal, sharply keeled ammonoid. In the paratype, the shell ornament is better preserved and shows slightly sigmoidal growth lines, which are reinforced like ribs on the keel of the conch.

The cross section of the holotype is well-preserved and allows the study of whorls from the initial stage to a conch diameter of 19.5 mm ( Fig. 67A ). Up to a diameter of 3 mm, the whorl profile is kidney-shaped; thereafter the formation of a ventral keel begins and already at 4.8 mm dm the venter is galeate. At about this diameter, the umbilicus begins to close. On the last half whorl, the galeate shape of the venter is abandoned and transformed into a simple, sharply keeled shape.

The small specimen MB.C.3723.1 already has a galeate venter with a clearly attached keel at 6.4 mm conch diameter ( Fig. 66C ). The shell shows rather coarse growth lines with a concave course across the flank.

Remarks

Voehringerites peracutus differs from all other species from the Gattendorfia Limestone of Oberrödinghausen by the divided external lobe. Similar in the conch shape is Acutimitoceras ucatum sp. nov., especially in the juvenile stage, but this species does not have the distinct keel. A distinct keel is present in A. acutum and A. paracutum sp. nov., but these two species show biconvex growth lines, whereas these are almost straight in V. peracutus .

Figures

Fig. 66. Voehringerites peracutus (Vöhringer, 1960) from the Oberrödinghausen railway cutting. A. Holotype GPIT-PV-63958 (Vöhringer Coll.) from bed 5. B. Paratype GPIT-PV-63966 (Vöhringer Coll.) from bed 5. C. Specimen MB.C.3723.1 (Weyer 1993–1994 Coll.) from bed 5a2. Scale bar units =1 mm.

Fig. 67. Voehringerites peracutus (Vöhringer, 1960); B, D after Korn & Weyer (2003). A. Cross section of holotype GPIT-PV-63958 (Vöhringer Coll.) from the Oberrödinghausen railway cutting, bed 5. B. Cross section of specimen MB.C.5245.1 (Weyer 1993–1994 Coll.) from the Hasselbachtal section, bed 72.C. Suture line of holotype GPIT-PV-63958 (Vöhringer Coll.) from the Oberrödinghausen railway cutting, bed 5, at dm = 21.5 mm, ww =6.8 mm, wh=12.0 mm. D. Suture line of specimen MB.C.5245.1 (Weyer 1993–1994 Coll.) from the Hasselbachtal section, bed 72, at dm =34.0 mm, ww =8.8 mm, wh= 19.5 mm. E–G. Ontogenetic development of the conch width index (ww/dm), umbilical width index (uw/dm), whorl width index (ww/wh) and whorl expansion rate (WER) of selected specimens. Scale bar units= 1 mm.