Ammonoids of the Middle Devonian family Maenioceratidae in the Anti-Atlas of Morocco Author Bockwinkel, Jürgen F7FE7EEA-B678-4FEE-879C-8C429F66BF3A Dechant-Fein-Strasse 22, 51375 Leverkusen, Germany. j.bockwinkel@t-online.de 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 text European Journal of Taxonomy 2024 2024-01-30 921 1 1 35 https://europeanjournaloftaxonomy.eu/index.php/ejt/article/download/2413/10641 journal article 10.5852/ejt.2024.921.2413 2118-9773 10590243 80B3C408-DD2C-4373-96AE-15F067D723F8 Trimaenioceras klugi gen. et sp. nov. urn:lsid:zoobank.org:act: D659BF7F-C9C9-4150-9CF5-73B94B957BCE Fig. 13 ; Table 10 Bensaidites n. sp. – Korn & Klug 2002: 141 , text-fig. 133h, k. Maenioceras n. sp. II – Aboussalam & Becker 2011 : text-figs 8.3–4. Diagnosis Species of Trimaenioceras gen. nov. with thickly discoidal and involute conch at 20 mm dm (ww/ dm ~ 0.50; uw/dm ~ 0.05) with weakly compressed whorl profile (ww/wh ~ 0.95) and low coiling rate (WER ~ 1.55). Whorl profile at 20 mm conch diameter horseshoe-shaped with convex, weakly convergent flanks, rounded ventrolateral shoulder and rounded venter. Ventrolateral shoulder without spiral groove. Growth lines fine. Suture line with very wide external lobe, deep, cuneiform, weakly asymmetric E 2 lobe, symmetrically rounded ventrolateral saddle and V-shaped, slightly asymmetric, acute lateral lobe. Etymology Named after Christian Klug, who discovered the ammonoid assemblage. Type material Holotype MOROCCO • Anti-Atlas , Tafilalt , Jebel Ouaoufilal ; middle Givetian ; Bockwinkel and Ebbighausen 2004 Coll.; MB.C.31967.1 (illustrated in Fig. 13A ). Paratypes MOROCCO • 241 specs; same collection data as for holotype; MB.C.31967.2 to MB.C.31967.242 • 24 specs; Oued Mzerreb-W ; beds 10/11 (middle Givetian ); Bockwinkel and Ebbighausen 2004 Coll.; MB.C.31968.1 to MB.C.31968.24 . Fig. 13. Trimaenioceras klugi gen. et sp. nov. A . Holotype MB.C.31967.1 from Jebel Ouaoufilal. B . Paratype MB.C.31967.2 from Jebel Ouaoufilal. C . Paratype MB.C.31968.1 from Oued Mzerreb-W, beds 10/11. D . Paratype MB.C.31967.3 from Jebel Ouaoufilal. E . Paratype MB.C.31967.2 from Jebel Ouaoufilal; suture line at wh = 6.4 mm. F . Paratype MB.C.31968.1 from Oued Mzerreb-W, beds 10/11; suture line at wh = 6.4 mm. G . Paratype MB.C.31967.4 from Jebel Ouaoufilal; cross section. Scale bar units = 1 mm. Table 10. Conch dimensions (in mm) and ratios of Trimaenioceras klugi gen. et sp. nov.

specimen	dm	ww	wh	uw	ah	ww/dm	ww/wh	uw/dm	WER	IZR
MB.C.31967.1	19.2	9.6	10.3	1.1	3.7	0.50	0.93	0.06	1.52	0.65
MB.C.31967.2	18.5	9.0	9.1	1.4	–	0.49	0.99	0.08	–	–
MB.C.31968.1	13.9	7.7	7.5	1.5	3.0	0.55	1.03	0.11	1.63	0.60
MB.C.31967.3	10.7	6.6	5.1	2.0	2.4	0.62	1.29	0.19	1.66	0.53

Description Holotype MB.C.31967.1 is a well-preserved limonitic internal mould with 19 mm conch diameter ( Fig. 13A ). The conch is thickly discoidal and involute (ww/dm = 0.50; uw/dm = 0.06) with a weakly compressed whorl profile (ww/wh = 0.93) and a low coiling rate (WER = 1.52). The flanks are nearly parallel; the ventrolateral shoulder and the venter are continuously rounded. The last phragmocone volution has 14 chambers. Paratype MB.C.31967.2 has, at 18.5 mm diameter, a conch with very similar proportions like the holotype ( Fig. 13B ). The suture line has an extremely wide external lobe, which is subdivided in three almost identical prongs. The E 1 lobe is lanceolate and separated from the asymmetric, cuneiform E 2 lobe by a nearly symmetric median saddle that reaches three quarters of the depth of the external lobe. The ventrolateral saddle is inverted U-shaped and nearly symmetric; the lateral lobe is slightly asymmetric V-shaped with convex ventral flank and nearly straight dorsal flank ( Fig. 13E ). The last phragmocone volution has 14 chambers. Paratypes MB.C.31968.1 ( 14 mm conch diameter; Fig. 13C ) and MB.C.31967.3 ( 11 mm conch diameter; Fig. 13D ) show the morphology of the intermediate growth stage, in which the umbilicus is being closed by increasing overlap of the inner flank upon the umbilicus. The suture line of paratype MB.C.31968.1 is similar to that of paratype MB.C.31967.2, but possesses less deep lobes ( Fig. 13F ). The ventrolateral saddle is narrowly rounded. The last phragmocone volution of paratype MB.C.31968.1 has 12 chambers. Paratype MB.C.31967.4 was sectioned, but shows that the inner whorls are not preserved ( Fig. 13G ). However, it shows clearly that the whorl profile is, at 12 mm conch diameter, horseshoe-shaped. It is widest in the midflank area, from where the flanks converge towards the umbilicus and the continuously rounded venter. The umbilical wall is very low and strongly convex. Remarks Trimaenioceras klugi gen. et sp. nov. is similar to T. eculeus gen. et sp. nov. , but differs in the more slender and narrowly umbilicate conch in comparative growth stages. At around 15 mm conch diameter, ~ 0. 50 and ~ 0.05 in T. klugi , but ww/dm~0.60 and uw/dm~ 0.25 in T. eculeus .