Gattendorfia subinvoluta (Münster, 1839)

Korn, Dieter & Weyer, Dieter, 2023, The ammonoids from the Gattendorfia Limestone of Gattendorf (Devonian-Carboniferous boundary; Upper Franconia, Germany), European Journal of Taxonomy 883, pp. 1-61 : 48-51

Gattendorfia subinvoluta (Münster, 1839)

Fig. 25 ; Table 16

Goniatites subinvolutus Münster, 1839: 23 , pl. 17 fig. 2.

Gattendorfia ventroplana Schindewolf, 1924: 105 .

Goniatites subinvolutus – Gümbel 1862: 305, pl. 5 fig. 36.

Sporadoceras subinvolutum – Frech 1902: 82, pl. 3 fig. 17.

Gattendorfia subinvoluta – Schindewolf 1923: 409, pl. 16 figs 9–10, text-fig. 14a–c; 1952: 295, text-fig. 15. — Schmidt 1929: 62, pl. 15 figs 12–13. — Librovitch 1940: pl. 3 fig. 5. — Miller & Collinson 1951: 467, pl. 69 fig. 18. — Pareyn 1961: 68, text-fig. 2a. — Bartzsch & Weyer 1982: 18, text-fig. 3. — Kullmann 1983: 234, text-fig. 2d. — Korn 1992b: pl. 1 figs 17–18, pl. 2 figs. 25, 28–29; 1994: 71, text-fig. 64a–c. — Schönlaub et al. 1992: pl. 4 figs 17–18, pl. 5 figs 25, 28–29.

non Gattendorfia subinvoluta – Schmidt 1924: 151, pl. 8 figs 7–8; 1925: 535, pl. 19 fig. 8. — Vöhringer 1960: 151, pl. 5 fig. 5, text-figs 26, 35. — Ruan 1981: 82, pl. 19 figs 20–22. — Korn 1994: 71, text-figs. 65a, 66a, 67c, 68c; 2006: text-fig. 3j. — Luppold et al. 1994: text-fig. 15b. — Korn & Feist 2007: 107, text-fig. 6e, g — Korn & Weyer 2003: 100, pl. 2 figs. 10–11, text-fig. 14g. — Kullmann 2009: text-fig. 3.1.

Diagnosis

Species of Gattendorfia with a conch reaching 90 mm diameter. Conch at 80 mm dm thinly discoidal, subevolute (ww/dm ~ 0.40; uw/dm ~ 0.40). Whorl profile in the juvenile stage trapezoidal, at 80 mm dm weakly depressed (ww/wh ~ 1.10); coiling rate low (WER ~ 1.70). Venter broadly rounded, umbilical margin narrowly rounded. Growth lines lamellar, wide-standing, with convex course; with short ribs on the umbilical margin. Without constrictions on the shell surface; without internal shell thickenings.

Material examined

Holotype GERMANY • 1 specimen; Upper Franconia , 400 m north-west of Kirchgattendorf; Münster Coll.; illustrated by Münster (1839b: pl. 17 fig. 1) and Korn (1994: text-fig. 56g), re-illustrated here in Fig. 25A ; SNSB BSPG AS VII 30.

Additional material GERMANY • 1 specimen; Upper Franconia , 400 m north-west of Kirchgattendorf; bed 21 (“ Gattendorfia Limestone ”); Schindewolf 1916 Coll.; MBG 3118 • 1 specimen; Upper Franconia , 400 m north-west of Kirchgattendorf; bed 21 (“ Gattendorfia Limestone ”); MB.C.8015 • 1 specimen; Upper Franconia , 400 m north-west of Kirchgattendorf; bed 21c–d (“ Gattendorfia Limestone ”); Korn 1989 Coll.; MB.C.31285 • 1 specimen; Upper Franconia , 400 m north-west of Kirchgattendorf; bed 21 (“ Gattendorfia Limestone ”); Schindewolf 1916 Coll.; SMF Mbg.3119 .

Description

Holotype SNSB BSPG AS VII 30 is a rather poorly preserved specimen with 80 mm conch diameter; although it allows the study of the conch form; it is strongly weathered without preserved shell remains ( Fig. 25A ). The conch is thinly discoidal and subevolute (ww/dm=0.38; uw/dm=0.37) and it can be assumed from a view into the umbilicus that the penultimate whorl had a similar shape. No constrictions are visible on the internal mould.

Specimen MB.C.8015 suffered from the very unprofessional earlier preparation in which the umbilicus and inner whorls were badly damaged ( Fig. 25C ). However, the specimen, which, at 60 mm conch diameter, has conch parameters very similar to the holotype, shows some areas of the shell surface with preserved ornament. This consists of lamellar, widely spaced growth lines extending with a backward direction across the flank and forming a broad, deep sinus on the venter. The specimen lacks constrictions.

Specimen SMF Mbg.3118 has a diameter of about 45 mm and is strongly deformed, especially near the aperture ( Fig. 25D ). It shows lamellar growth lines directed backwards on the flank.

The holotype of “ G. ventroplana ” (MBG3119) is a corroded specimen that has grown to 12 mm in diameter with seven whorls ( Fig. 25B ). The conch is serpenticonic and very evolute (uw/dm ~ 0.55) with a broad, rounded-trapezoidal whorl profile (ww/wh ~ 1.70). The venter is flattened and separated from the flanks and umbilical wall by a rounded shoulder. The specimen does not bear any shell remains. The internal form, however, has three moderately deep constrictions per whorl; these run rursiradiate immediately from the umbilicus and form a shallow ventral sinus. There are three of these constrictions on each of the last and penultimate whorls; they are spaced at intervals greater than 90 degrees.

Remarks

The name Gattendorfia subinvoluta has long been used to unite material with quite widely varying morphology. Vöhringer (1960) and subsequently Korn (1994) classified specimens from the lower part of the Hangenberg Limestone of Oberrödinghausen as G. subinvoluta ; however, these are clearly distinguished from G. subinvoluta by their fine shell constrictions and the broader conch. They were described as the new species G. rhenana by Korn & Weyer (2023).

Gattendorfia subinvoluta can be easily distinguished from most of the other species of the genus by the absence of shell constrictions. Another species without constrictions is G. costata , but this species has a much broader, pachyconic conch.

The species of Gattendorfia described by Bockwinkel & Ebbighausen (2006) and Ebbighausen & Bockwinkel (2007) from the Anti-Atlas do not possess shell constrictions, however, all are considerably more narrowly umbilicate and have a wider adult conch.

Schindewolf (1923) initially regarded the single specimen MBG.3319 as inner whorls of Gattendorfia subinvoluta ; a year later he named the new species G. ventroplana . Thereafter, the species was almost always regarded as a younger synonym of G. subinvoluta ( Vöhringer 1960; Korn 1994). Unfortunately, the larger specimens of the species do not provide any insight into the inner whorls, so that it cannot be clarified completely whether the specimen of G. ventroplana , which is only 12 mm in size, is merely the juvenile stage of G. subinvoluta .

Figures

Fig. 25. Gattendorfia subinvoluta (Münster, 1839) from Gattendorf. A. Holotype SNSB BSPG AS VII 30 (Münster Coll.). B. Holotype of “Gattendorfia ventroplana Schindewolf, 1923” SMF Mbg.3119 (Schindewolf 1916 Coll.). C. Specimen MB.C.8015. D. Specimen SMF Mbg.3118 (Schindewolf 1916 Coll.). Scale bar units=1 mm.