Eocanites supradevonicus (Schindewolf, 1926)

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 : 204-206

Eocanites supradevonicus (Schindewolf, 1926)

Fig. 124 ; Table 120

Protocanites supradevonicus Schindewolf, 1926: 104 , text-figs 3a, 4–5.

Protocanites supradevonicus supradevonicus – Bartzsch & Weyer 1982: 19, text-fig. 4/1.

non Protocanites supradevonicus supradevonicus – Vöhringer 1960: 171, pl. 6 fig. 2, text-figs 46b, 48.

non Eocanites supradevonicus – Korn 1994: 80, text-figs 66m, 73e, 74c, 75a; 2006: text-fig. 4J. — Kullmann 2000: text-fig. 4m. — Furnish et al. 2009: text-fig. 117.2.

Diagnosis

Species of the genus Eocanites with a conch reaching 50 mm diameter. Conch at 30 mm dm evolute (uw/dm ~0.55) with a weakly compressed whorl profile (ww/wh ~0.85) and a broadly rounded venter. Ornament with fine, weakly rursiradiate, concavo-convex growth lines with moderately deep ventral sinus. With low, rounded radial folds.

Material examined

Neotype

GERMANY • Rhenish Mountains , Oberrödinghausen , railway cutting ; Hangenberg Limestone , bed 3b ; Weyer 1993–1994 Coll.; illustrated in Fig. 124 ; MB.C. 31246 .

Description

Neotype MB.C.31246 is a rather well-preserved, fully shell-covered specimen with 45 mm conch diameter ( Fig. 124 ). It is extremely discoidal and evolute (ww/dm = 0.21; uw/dm = 0.54) with a compressed whorl profile (ww/wh = 0.81). The coiling rate is moderate (WER = 1.76). The whorl profile is widest in the dorsal flank region; from there the flanks slowly converge towards the broadly rounded venter. The well-preserved shell ornament has fine, sharp growth lines at different distances; they extend from the umbilicus slightly in backward direction. They form a lateral sinus on the middle of the flank and curve anteriorly to a ventrolateral projection and a rather shallow ventral sinus. In addition, there are very shallow radial folds (about eight per quarter whorl), which are most prominent on the inner and outer flanks; they are usually very weak on the middle of the flank and diminish before reaching the venter.

Remarks

Schindewolf (1926b) did not select a holotype when describing the species Eocanites supradevonicus ; a type specimen was obviously not subsequently dedicated as a lectotype. Vöhringer (1960) did not give any information on a type of the species in his monograph either. He also did not discuss the possible differences in conch shape and ornament between his specimens and the original description given by Schindewolf (1926b). To stabilise the species, a neotype from the Weyer collection from the type locality is proposed here.

The specimen already illustrated by Vöhringer (1960) as Eocanites supradevonicus obviously has a much weaker ornamentation than the specimen of the poor illustration given by Schindewolf (1926b), which is very evolute and shows an ornament composed of very low radial folds and growth lines.

Eocanites supradevonicus differs from most of the other Central European species of the genus by its very wide umbilicus (uw/dm ~0.55), which in many of the other species only reaches a width of 0.50 in the adult stage. Furthermore, E. supradevonicus differs from most species by its weak folds on the flank.

Figures

Fig. 124. Eocanites supradevonicus (Schindewolf, 1926) from the Oberrödinghausen railway cutting, neotype MB.C.31246 (Weyer 1993–1994 Coll.) from bed 3b. Scale bar units= 1 mm.