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

Cymaclymenia aulax n. sp.

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 .

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.

Figures

Figure 25. Cymaclymenia aulax n. sp. from the Anti-Atlas of Morocco; all × 1.0. (A) Holotype MB.C.22651 (Ebbighausen 2008 Coll.) from Aguelmous. (B) Paratype MB.C.22650 (Ebbighausen 2003 Coll.) from Lambidia (Aguelmous). (C) Paratype MB.C.22690 (Ebbighausen Coll.) from Fezzou.