Cymaclymenia carnata, 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 : 24

Cymaclymenia carnata n. sp.

Figure 26

Derivation of name: After Lat. carnatus, -a, -um (adj.) = thick; because of the stout conch form.

Holotype: Specimen MB.C.22654 (Kullmann Coll.); illustrated here in Fig. 26a, b .

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

Material: 2 specimens with a maximum conch diameter of 55 mm.

Diagnosis: Species of Cymaclymenia with thinly discoidal conch in the adult stage (ww / dm = 0.42); whorl cross section weakly compressed (ww / wh = 0.90). Conch shape in the intermediate stage (10 mm dm) thinly pachyconic and subinvolute (ww / dm = 0.62; uw / dm = 0.28). Umbilical wall steep in the adult stage, flanks moderately converging, venter broadly rounded. Ornament with fine biconvex growth lines, without riblets.

Discussion: Cymaclymenia carnata has, together with C. nephroides , the stoutest conch of all Cymaclymenia species. The two species can be separated by the umbilical width; C. carnata is more involute (ww / dm = 0.20) than C. nephroides (uw / dm = 0.25).

Figures

Figure 26. Cross sections (A, C; all × 1.5), photograph (B; × 1.0) and ontogenetic trajectories (D–G) of Cymaclymenia carnata n. sp. from the Anti-Atlas of Morocco. (A, B) Holotype MB.C.22654 (Kullmann Coll.) from Aguelmous. (C) Paratype MB.C.22645 (Korn 2009 Coll.) from Madène el Mrakib. (D) Conch width index (ww / dm). (E) Umbilical width index (ww / wh). (F) Whorl width index (uw /dm). (G) Whorl expansion rate (WER).