Weyerella reticulum ( 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 : 157-159

Weyerella reticulum ( Vöhringer, 1960)

Figs 8C , 94–95 ; Tables 91–92

Gattendorfia reticulum Vöhringer, 1960: 156 , pl. 5 fig. 3, text-fig. 31.

Gattendorfia reticulum – Korn 1992b: 17, pl. 2 figs 34–35; 1994: 74, text-figs 65h, 67g, 68b. — Schönlaub et al. 1992: pl. 5 figs 34–35. — Korn & Weyer 2003: 100, pl. 2 fig. 5.

Diagnosis

Species of Weyerella with a conch reaching 25 mm diameter. Conch at 15 mm dm thickly discoidal, subevolute (ww/dm ~0.45; uw/dm ~0.42). Whorl profile at 15 mm dm weakly depressed (ww/wh ~1.30); coiling rate low (WER ~1.65). Venter broadly rounded, umbilical margin narrowly rounded. Growth lines coarse, wide-standing, with convex course; ventral sinus very deep. The combination of growth lines with spiral lines cause a reticulate ornament. Without constrictions on the shell surface; without internal shell thickenings. Suture line with narrowly lanceolate, pouched external lobe and very narrow, lanceolate adventive lobe.

Material examined

Holotype

GERMANY • Rhenish Mountains, Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 6 ; Vöhringer Coll.; illustrated by Vöhringer (1960: pl. 5 fig. 3) and Korn (1994: text-fig. 65h); re-illustrated here in Fig. 94 ; GPIT-PV-63974.

Paratypes

GERMANY • 4 specimens; Rhenish Mountains , Oberrödinghausen, railway cutting; Hangenberg Limestone, bed 5; Vöhringer Coll.; GPIT-PV-63975–GPIT-PV-63976, GPIT-PV-63979, GPIT-PV-63991 .

Additional material

GERMANY • 1 specimen; Rhenish Mountains , Hasselbachtal; Hangenberg Limestone, bed 62A; Weyer 1993–1994 Coll.; MB.C.5242.1 .

Description

Holotype GPIT-PV-63974 has almost 15 mm conch diameter and is well-preserved and covered with shell remains ( Fig. 94 ). The conch is discoidal and subevolute (ww/dm = 0.46; uw/dm = 0.43) with weakly depressed, continuously rounded whorl profile. The shell surface shows a combination of coarse growth lines, which are directed backwards already on the umbilical wall and flank and form a deep and broad ventral sinus, and spiral lines, which are less prominent than the growth lines. Shell constrictions are not present.

The suture line of paratype GPIT-PV-63975 is characterised by very narrow lobes ( Fig. 95B ). The external lobe is lanceolate and weakly pouched; next to it follows the weakly asymmetrical ventrolateral saddle and then the symmetrical, lanceolate adventive lobe, which has almost the same shape as the external lobe.

The sectioned paratype GPIT-PV-63991 shows only the whorl up to 5.5 mm conch diameter ( Fig. 95A ). The whorl profile is always crescent-shaped with a slowly decreasing ww/wh ratio from about 2.00 at 2 mm conch diameter to about 1.70 at 5.5 mm dm ( Fig. 95E ).

Remarks

Weyerella reticulum is easily distinguished from the other species of the genus by its reticulate ornament.

Figures

Fig. 8. Early Tournaisian representative ammonoids of the family Gattendorfiidae from the Hasselbachtal section, all Weyer 1993–1994 Coll. A. Gattendorfia rhenana sp. nov., paratype MB.C.5244.1 from bed 71. (Illustrated by Korn & Weyer 2003: pl. 2 figs 10–11, as Gattendorfia subinvoluta.) B. Weyerella molaris (Vöhringer, 1960), specimen MB.C.5240.8 from bed 57. C. Weyerella reticulum (Vöhringer, 1960), specimen MB.C.5242.1 from bed 62. D. Hasselbachia multisulcata (Vöhringer, 1960), specimen MB.C.5240.1 from bed 57. E. Hasselbachia gracilis (Vöhringer, 1960), specimen MB.C.5240.5 from bed 57. F. Pseudarietites westfalicus Schmidt, 1924, specimen MB.C.5236.1 from bed 49. Scale bar units =1 mm.

Fig. 94. Weyerella reticulum (Vöhringer, 1960), holotype GPIT-PV-63974 Vöhringer Coll.) from the Oberrödinghausen railway cutting, bed 6. Scale bar units =1 mm.

Fig. 95. Weyerella reticulum (Vöhringer, 1960) from the Oberrödinghausen railway cutting; all Vöhringer Coll. A. Cross section of paratype GPIT-PV-63991 from bed 5. B. Suture line of paratype GPIT-PV-63975 from bed 5, at dm=11.5 mm, ww = 6.5 mm, wh =4.0 mm. C. Growth line course of holotype GPIT-PV-63974 from bed 6, at dm=14.2 mm, ww =7.2 mm, ww =5.4 mm. D–F. Ontogenetic development of the conch width index (ww/dm), umbilical width index (uw/dm), whorl width index (ww/wh) and whorl expansion rate (WER). Scale bar units =1 mm.