Parahoplites sp.

Frau, Camille, 2023, Upper Aptian Ammonites From Roussillon, Southern France, Fossil Imprint 79 (1), pp. 89-101 : 98

Parahoplites sp.

Text-fig. 4n, o

M a t e r i a l. Two specimens LGB-ROU.7 ( Text-fig. 4n ) and LGB-ROU.8 ( Text-fig. 4o ).

D e s c r i p t i o n. Specimen LGB-ROU.7 is a moderate-size septated fragment. Ribbing is an alternation of dense, sharp slightly flexuous, simple primary ribs and one or two secondary ribs, starting low on the flanks. All ribs pass over the venter rather straight. The umbilical wall is steep, almost recurved internally.

Specimen LGB-ROU.8 is a moderate-size incomplete ammonite. Ribbing of the inner whorls is an alternation of strong, slightly flexuous, simple primary and secondary ribs. Secondaries start at mid-flank. On the remaining body chamber, the ribbing is progressively less pronounced, eventually disappearing altogether. There remains a strong, regular peri-umbilical bullae with a slight retrocurvature, and uniform ribs over the upper flank and venter. The umbilical wall is steep, almost recurved internally.

D i s c u s s i o n. The Parahoplitidae Parahoplites is considered a cosmopolitan upper Aptian ammonite ( Lehmann et al. 2015). The genus unfortunately suffered from extreme taxonomic splitting ( Klein and Bogdanova 2013), and homeomorphy has led to erroneous taxonomic interpretations, in particular with the New World faunas ( Ovando-Figueroa et al. 2018?). Parahoplites should be limited to the various Boreal-Atlantic species, for which the taxonomy needs simplification. The material at our disposal is not identified to the species level, due to defective preservation, but the greatest affinities are found with the species Parahoplites grossouvrei ( JACOB, 1905) and Parahoplites campichii ( PICTET et RENEVIER, 1854) for specimen LGB-ROU.8, while specimen LGB-ROU.7 is closer to Parahoplites nutfieldensis (SOWERBY, 1815) .

O c c u r r e n c e. The distribution of a Parahoplites assemblage has long been recognized in the Boreal-Atlantic Subrealm, and is identified to the Parahoplites melchioris Zone in the Caucasus and the Parahoplites nutfieldensis Zone in UK ( Bogdanova and Mikhailova 2016, and references therein). Only rare occurrences are found in the adjacent areas, such as in the Vocontian Basin of SE France, where the genus is reported within ( Dauphin 2002) or above ( Joly and Delamette 2008) the Fallot black shale episodes.

Figures

Text-fig. 4. Roussillon’s specimens assigned to Egoianiceras angulatum (EGOIAN, 1969).