Progoniatites maghribensis, Korn & Bockwinkel & Ebbighausen & Klug, 2003

Korn, Dieter, Bockwinkel, Jürgen, Ebbighausen, Volker & Klug, Christian, 2003, Palaeobiogeographic and evolutionary meaning of an early Late Tournaisian ammonoid fauna from the Tafilalt of Morocco, Acta Palaeontologica Polonica 48 (1), pp. 71-92 : 89-90

publication ID	https://doi.org/ 10.5281/zenodo.13272527
persistent identifier	https://treatment.plazi.org/id/03BE87DE-5A62-FFD4-FCF8-F902770EF979
treatment provided by	Felipe
scientific name	Progoniatites maghribensis
status	sp. nov.

Treatment

Progoniatites maghribensis View in CoL sp. nov.

Figs. 30D–F View Fig , 31 View Fig , 32 View Fig .

Derivation of name: After Maghrib, the Arabian name for north−west Africa.

Holotype: Specimen MB.C.3978 (coll. Klug), Fig. 30D View Fig .

Type locality and horizon: Taouz, Jebel Ouaoufilal, locality B east of Ksar Bouhamed (Tafilalt, Morocco); Oued Znaïgui Formation, early Late Tournaisian.

Material.— 32 specimens (only few of which are complete and undistorted phragmocones), 8 to 18 mm in diameter.

Diagnosis.— Progoniatites with globose conch between 5 and 15 mm diameter (ww/dm 0.85 to 1.00). Umbilicus at 8 mm diameter very narrow (uw/dm 0.06) and little wider at 15 mm diameter (uw/dm 0.15). Umbilical margin rounded. Steinkerns with two or three constrictions. Suture line with V−shaped external lobe, moderate median saddle (40% of external lobe depth), and asymmetrical adventive lobe.

Description.—Theconchwidthshowssomevariability( Fig.31 View Fig ), but all measured specimens are globular, with width/conch diameter ratios between 0.84 and 1.01. The umbilicus is in all stages very narrow, but it opens slightly during ontogeny. In specimens between 10 and 15 mm conch diameter it measures between 0.08 and 0.14. The umbilical margin is rounded and the umbilical wall is steep. The steinkern is smooth, and only two linear constrictions per whorl across the flanks and venter.

The goniatitid suture of the holotype MB.C.3978 ( Fig. 32 View Fig ) shows a narrow V−shaped external lobe with almost linear flanks, and a median saddle with a height of approximately 40% of the external lobe depth. The ventrolateral saddle is subacute with a very narrowly rounded top. Both flanks of the adventive lobe are convexly arched .

Dimensions.—(in mm). Comparisons.— P. maghribensis sp. nov. can hardly be confused with any other of the described Tournaisian species. Poorly known “ Glyphioceras angustilobatum Schindewolf, 1926 " from nodules within the Russschiefer of Zadelsdorf of Thuringia has a more compressed conch (ww/dm approximately 0.65) than P. maghribensis sp. nov., similarly as does P. karensis ( Kusina, 2000) (ww/dm 0.55).

Some similarity to P. maghribensis sp. nov. is shown by species of Zhifangoceras Sheng, 1984 : Z. subglobosum Sheng, 1984 (ww/dm 0.55) and Z. zhifangense Sheng, 1984 (ww/dm 0.40) have a much more discoidal conch than P. maghribensis sp. nov.