Cymaclymenia aulax, Klein & Korn, 2014

Klein, C. & Korn, D., 2014, A morphometric approach to conch ontogeny of Cymaclymenia and related genera (Ammonoidea, Late Devonian), Fossil Record 17 (1), pp. 1-32 : 23

publication ID	https://doi.org/ 10.5194/fr-17-1-2014
DOI	https://doi.org/10.5281/zenodo.10997818
persistent identifier	https://treatment.plazi.org/id/4D1287FB-CB26-FFC2-FF98-33E5FDA1FB59
treatment provided by	Felipe
scientific name	Cymaclymenia aulax
status	sp. nov.

Treatment

Cymaclymenia aulax View in CoL n. sp.

Figure 25 View Figure 25

Derivation of name: After Lat. aulax (noun) = furrow; because of the steinkern constrictions.

Holotype: Specimen MB.C.22651 (Ebbighausen 2008 Coll.); illustrated here in Fig. 25a View Figure 25 .

Type locality and horizon: Aguelmous (Anti-Atlas); probably Kalloclymenia Assemblage (late Famennian).

Material: 3 specimens with a maximum conch diameter of 60 mm.

Diagnosis: Species of Cymaclymenia with thinly discoidal and subevolute conch in the adult stage (ww / dm = 0.30; uw / dm = 0.30); whorl cross section weakly compressed (ww / wh = 0.65). Umbilical wall steep in the adult stage, flanks weakly converging, venter rounded. Ornament with rather coarse biconvex growth lines, without riblets; steinkern with curved constrictions on the flanks.

Discussion: C. aulax belongs to the few species of the genus with coarse steinkern constrictions. Münster (1832) described the species “ Planulites semistriatus ” from Franconia, which also belongs to Cymaclymenia . This species also possesses steinkern constrictions on the flanks and venter. C. semistrata has a very slender conch (ww / dm = 0.26 at 30 mm dm) in contrast to the stouter C. aulax (ww / dm = 0.32 at a comparable diameter). C. sudetica ( Renz, 1914) from Silesia possesses steinkern constrictions, but has a stouter conch shape.

The new species differs from the other species of Cymaclymenia from the Anti-Atlas by the presence of conspicuous steinkern constrictions. C. formosa is the most similar of the other species, but C. aulax also differs in the increasing umbilical width index in the adult stage.