The ammonoids from the Gattendorfia Limestone of Oberrödinghausen (Early Carboniferous; Rhenish Mountains, Germany) Author Korn, Dieter 286CA4F3-7EBC-4AEF-A66A-B2508D001367 Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany. dieter.korn@mfn.berlin Author Weyer, Dieter A09A1738-C70E-4F22-A069-8B7DB4A1753D Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, 10115 Berlin, Germany. dieter.weyer@t-online.de text European Journal of Taxonomy 2023 2023-07-19 882 1 230 http://dx.doi.org/10.5852/ejt.2023.882.2177 journal article 58033 10.5852/ejt.2023.882.2177 57d1d191-2bf5-4229-a0f5-9ab472a114a6 2118-9773 8177581 67C909E4-C700-4F8D-B8CE-5FD9B2C5D549 Eocanites delicatus sp. nov. urn:lsid:zoobank.org:act: 84F708EA-F37B-4DF4-8503-B777178537CA Figs 125–126 ; Tables 121–122 Protocanites Lyoni – Schmidt 1924: 153 , pl. 8 figs 14–18. — Schmidt, 1925: 537 , pl. 19 fig. 11. Protocanites supradevonicus supradevonicus – Vöhringer 1960: 171 , pl. 6 fig. 2, text-figs 46b, 48. Eocanites supradevonicus – Korn 1994: 80 , text-figs 66m , 73e, 74c, 75a; 2006: text-fig. 4j. — Kullmann 2000 : text-fig. 4m . — Sprey 2002: 53 , text-fig. 18g . — Furnish et al . 2009 : text-fig. 117.2. Diagnosis Species of the genus Eocanites with a conch reaching 60 mm diameter. Conch at 12 mm dm evolute (uw/dm ~0.55) with weakly depressed whorl profile (ww/wh ~1.10) and broadly rounded venter; conch at 30 mm dm evolute (uw/dm ~0.50) with nearly circular whorl profile (ww/wh ~1.00) and broadly rounded venter. Ornament with fine, rursiradiate, concavo-convex growth lines with moderately deep ventral sinus. With low, rounded folds on the flank. Suture line with weakly pouched external lobe and lanceolate, weakly pouched adventive lobe. Etymology From the Latin ‘ delicatus ’, referring to the delicate shell ornament. Material examined Holotype GERMANY • Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , bed 1; Vöhringer Coll.; illustrated by Vöhringer (1960 : pl. 6 fig. 2), Korn (1994: text-fig. 73e) and Korn (2006 : text-fig. 4j); re-illustrated here in Fig. 125A .; GPIT-PV-63997. Paratypes GERMANY • 1 specimen ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone ,bed1; Vöhringer Coll. ;GPIT-PV-64008 • 2specimens ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , bed 2; Vöhringer Coll. ; GPIT-PV-63981, GPIT-PV-63999 • 2 specimens ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , loose material; Korn 1977 Coll. ; MB.C.31247.1–2 • 2 specimens ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , loose material; Korn 1990 Coll. ; MB.C.31248.1–2 • 1 specimen ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , bed 2b; Korn 1991 Coll. ; MB.C.31249 • 2 specimens ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , bed 1; Weyer 1993–1994 Coll. ; MB.C.31250.1–2 • 10 specimens ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , bed 2a; Weyer 1993–1994 Coll. ; MB.C.31251.1–10 • 2 specimens ; Rhenish Mountains , Oberrödinghausen , railway cutting; Hangenberg Limestone , bed 2b; Weyer 1993–1994 Coll. ; MB.C.31252.1–2 . Description Holotype GPIT-PV-63997 is a well-preserved specimen with 42 mm conch diameter embedded in rock matrix ( Fig. 125A ). The conch is extremely discoidal with a wide umbilicus (ww/dm ~0.25; uw/dm ~0.50) and a compressed oval whorl profile (ww/wh ~0.85); the coiling rate is low (WER ~1.70). The shell bears fine, regularly spaced growth lines that are directed backwards on the flank. A very weak radial folding is also visible on the flank. Paratype MB.C.31247.1 is a specimen with 31 mm diameter ( Fig. 125B ); it is thinly discoidal and evolute with a nearly circular whorl profile (ww/dm ~0.28; uw/dm ~0.50; ww/wh ~0.96). The ornament consists of fine growth lines running backwardly directed across the flanks and form a rounded ventral sinus. Eocanites delicatus sp. nov. has, like most of the other early prolecanitid ammonoids, a rather simple conch ontogeny with nearly monophasic trajectories of the cardinal conch parameters. As seen in specimens GPIT-PV-64008 ( Fig. 126A ) and GPIT-PV-63981 ( Fig. 126B ), the uw/dm trajectory decreases from about 0.65 at 1.2 mm diameter to 0.28 at 12 mm diameter. The uw/dm trajectory shows an initial increase to 0.57 at 3 mm diameter and then stays at this value. The whorl expansion rate fluctuates between 1.60 and 1.70 in the growth interval between 2 and 12 mm diameter ( Fig. 126E–G ). Fig. 125. Eocanites delicatus sp. nov. from the Oberrödinghausen railway cutting. A . Holotype GPIT- PV-63997 (Vöhringer Coll.) from bed 1. B . Paratype MB.C.31247.1 (Korn 1977 Coll.) from an unknown bed. Scale bar units = 1 mm. Table 121. Conch measurements, ratios and rates of Eocanites delicatus sp. nov. from Oberrödinghausen.

specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
GPIT-PV-64008	47.0	11.7	13.9	22.9	12.5	0.25	0.84	0.49	1.86	0.09
GPIT-PV-63997	42.3	9.7	11.5	21.8	9.8	0.23	0.84	0.52	1.69	0.15
GPIT-PV-63997	31.6	7.2	8.3	15.9	–	0.23	0.88	0.50	–	–
GPIT-PV-63981	11.5	3.1	2.9	6.4	2.6	0.27	1.07	0.56	1.67	0.09
MB.C.31247.1	31.1	8.6	9.0	15.5	8.1	0.28	0.96	0.50	1.82	0.10

Table 122. Conch ontogeny of Eocanites delicatus sp. nov. from Oberrödinghausen.

dm	conch shape	whorl cross section shape	whorl expansion
3 mm	thinly discoidal; evolute	moderately depressed; weakly embracing	low
(ww/dm ~0.35; uw/dm ~0.55)	(ww/wh ~1.55; IZR ~0.10)	(WER ~1.60)
10 mm	extremely discoidal; evolute	weakly depressed; weakly embracing	low
(ww/dm ~0.30; uw/dm ~0.55)	(ww/wh ~1.05; IZR ~0.10)	(WER ~1.60)
30 mm	extremely discoidal; evolute	weakly compressed; weakly embracing	moderate
(ww/dm ~0.25; uw/dm ~0.50)	(ww/wh ~0.95; IZR ~0.10)	(WER ~1.80)

Remarks The holotype that was illustrated by Vöhringer (1960) under the name Eocanites supradevonicus has a much weaker ornament than the specimen of the poor illustration given by Schindewolf (1926b) and is thus not included in that species. Eocanites delicatus sp. nov. can be distinguished from E. supradevonicus by several characteristics. Firstly, the conch of E. delicatus is slightly less widely umbilicate (uw/dm ~ 0.50 in contrast to E. supradevonicus with a value of ~0.55) and secondly, E. delicatus shows only very weak folds on the flank, which are developed much stronger in E. supradevonicus . Eocanites delicatus differs from the similar species E. brevis in the shape of the whorl profile, which in E. delicatus is still almost circular at 35 mm conch diameter, whereas in E. brevis it is already compressed at 10 mm conch diameter (ww/ wh ~0.90). Eocanites planus and E. tener also differ from E. delicatus in this respect.