The early gephuroceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea) 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 Bockwinkel, Jürgen F7FE7EEA-B678-4FEE-879C-8C429F66BF3A Dechant-Fein-Strasse 22, 51375 Leverkusen, Germany. jbockwinkel@t-online.de text European Journal of Taxonomy 2022 2022-06-08 823 10 47 http://zoobank.org/d5ac626b-4a10-4cd9-b77b-6d7efe8d180e journal article 68733 10.5852/ejt.2022.823.1811 5cb7c978-e62d-4576-b32d-2469745af89a 2118-9773 6628057 D5AC626B-4A10-4CD9-B77B-6D7EFE8D180E Acanthoclymenia forcipifera (Sandberger & Sandberger, 1851) Figs 19–20 Goniatites forcipifer Sandberger & Sandberger, 1851: 81 , pl. 6 fig. 3. Gephyroceras forcipiferum – Wedekind 1913: 51 ; 1918: 122 , text-fig. 28f. Ponticeras forcipiferum – Matern 1931: 84 . Probeloceras forcipiferum – House in House & Ziegler 1977: 80 , pl. 3 figs 28–29. Acanthoclymenia forcipifer – Korn & Klug 2002: 119 , text-fig. 123d. Acanthoclymenia genundewa – Dzik 2002 : text-fig. 50f–i. non Probeloceras forcipiferum – Petter 1959: 155 , pl. 11 figs 11–12, text-fig. 40e. — Ruan 1981: 42 , pl. 9 figs 1–5, 8, text-fig. 16. Diagnosis Species of Acanthoclymenia reaching about 40 mm conch diameter with extremely discoidal, subinvolute conch between 12 and 28 mm dm (ww/dm = 0.20–0.25; uw/dm ~ 0.28); coiling rate very high (WER increasing from 2.25 to 2.60). Whorl profile strongly compressed (ww/wh ~ 0.50); umbilical wall shallow and rounded, whorl profile pear-shaped, ventrolateral margin angular, venter flat or slightly concave. Growth lines very fine, strongly biconvex. Material examined Lectotype GERMANY • Rhenish Mountains , Oberscheld ; early Frasnian (Red Ironstone) ; Wiesb. 36a. Illustrated by Sandberger & Sandberger (1850 –1856: pl. 6 fig. 3), re-illustrated by House in House & Ziegler (1977 : pl. 3 figs 28–29) and here ( Fig. 19 ). Additional material GERMANY • 1 specimen ; Rhenish Mountains , Oberscheld (Eiserne Hand, Betagrube); early Frasnian (Red Ironstone) ; Trempel Coll .; MB.C.30432 • 1 specimen ; Rhenish Mountains , Oberscheld (Eiserne Hand, Grube Friedrich); early Frasnian (Red Ironstone) ; Kegel Coll .; MB.C.3669 • 9 specimens ; Rhenish Mountains , Oberscheld ( Grube Anna ); early Frasnian (Red Ironstone) ; Koch Coll .; MB.C.22199.1 , MB.C.22199.2 , MB.C.22199.3 , MB.C.22200 , MB.C.30433.1 , MB.C.30433.2 , MB.C.30433.3 • 1 specimen ; Rhenish Mountains , Oberscheld (Grube Sahlgrund, 205 m-Sohle); early Frasnian (Red Ironstone) ; MB.C.30434 • 1 specimen ; Rhenish Mountains , Oberscheld ( Grube Stillingseisenzug ); early Frasnian (Red Ironstone) ; Möbus 1901 Coll. ; MB.C.30435 • 1 specimen ; Rhenish Mountains , Oberscheld ( Grube Ypsilanta ); early Frasnian (Red Ironstone) ; Etzold 1910 Coll. ; MB.C.30436 • 1 specimen ; Rhenish Mountains , Oberscheld ( Grube Ypsilanta ); early Frasnian (Red Ironstone) ; Lotz 1901–1902 Coll. ; MB.C.30437 . Fig. 19. Acanthoclymenia forcipifera (Sandberger & Sandberger, 1851) ; lectotype 36a in the Wiesbaden collection from Oberscheld; photograph, dorsal reconstruction and reproduction of the figure of Sandberger & Sandberger (1850 –1856: pl. 6 fig. 3, 3a). Scale bar units = 1 mm . Description Six specimens are selected for description and illustration: Lectotype Wiesb. 36a: fully septate specimen with 16 mm conch diameter in haematitic ironstone ( Fig. 19 ). MB.C.22199.1: rather well-preserved specimen with 28 mm conch diameter in haematitic iron ore; largely covered with shell ( Fig. 20A ). MB.C.22199.2: well-preserved, slightly deformed specimen with 14 mm conch diameter in haematitic iron ore; largely covered with shell ( Fig. 20D ). MB.C.30433.1: well-preserved, slightly deformed specimen with 27 mm conch diameter in haematitic iron ore; largely covered with shell ( Fig. 20B ). Fig. 20. Acanthoclymenia forcipifera (Sandberger & Sandberger, 1851) , all Koch Coll from Oberscheld (Anna Mine). A . Specimen MB.C.22199.1. B . Specimen MB.C.30433.1. C . Specimen MB.C.30433.2. D . Specimen MB.C.22199.2. Scale bar units = 1 mm . Table 8. Conch dimensions and ratios of selected specimens of Acanthoclymenia forcipifera (Sandberger & Sandberger, 1851) .

Specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZW
MB.C.22199.1	27.5	6.2	11.7	7.4	10.4	0.22	0.52	0.27	2.60	0.11
MB.C.30433.1	26.3	6.3	12.2	6.6	10.0	0.24	0.51	0.25	2.61	0.18
MB.C.30433.2	21.4	5.0	9.6	5.6	7.9	0.23	0.52	0.26	2.53	0.17
MB.C.22199.2	13.6	3.2	6.0	3.9	4.6	0.24	0.54	0.29	2.27	0.24

MB.C.30433.2: well-preserved, slightly deformed specimen with 22 mm conch diameter in haematitic iron ore; largely covered with shell ( Fig. 20C ). MB.C.30433.3: fragmentary specimen co-occurring in a block of haematitic iron ore together with a specimen Crickites Wedekind, 1913 . The specimens MB.C.22199.2 ( 14 mm dm), MB.C.30433.2 ( 22 mm dm), MB.C.30433.1 ( 27 mm dm) and MB.C.22199.1 ( 28 mm dm) show that, during this growth interval, no significant changes in the conch proportions can be recognised ( Fig. 20 ). The conchs are extremely discoidal and subinvolute with very high coiling rate; the whorl profile is compressed. The umbilical wall is very shallow; the flanks converge towards the angular ventrolateral shoulder, the outer flanks are weakly incurved and the venter is flat. The ornament consists of fine growth lines with biconvex course; they extend with a very low dorsolateral projection on the umbilical margin and a high and narrow ventrolateral projection across the flanks. Faint short riblets are present around the umbilicus. Remarks When Sandberger & Sandberger (1850 –1856) described the new species Goniatites forcipifer , they did not make it clear whether the species name (“carrying a fire tong”) was a noun or an adjective. Since such species names are usually considered adjectives, we here decline it to the feminine form. Acanthoclymenia forcipifera differs from the second species of the genus from Oberscheld, A. planorbis (Sandberger & Sandberger, 1851) , in the much narrower umbilicus at 12 mm conch diameter (uw/dm ~ 0.30 in A. forcipifera but ~ 0.50 in A. planorbis ).