Procymaclymenia ebbighauseni, 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 : 11-12

Procymaclymenia ebbighauseni n. sp.

Figures 11 and 12

1960 Cymaclymenia striata . – Petter, p. 47, pl. 8, figs. 3, 5, 11, 14. 1999 Cymaclymenia sp. – Korn, p. 170, pl. 4, fig. 6.

2002 Cymaclymenia pudica . – Becker et al., p. 171, pl. 4, figs. 4, 5.

Derivation of name: In honour of Volker Ebbighausen (1940–2011), for his contribution to the palaeontology of the Anti-Atlas of Morocco.

Holotype: Specimen MB.C.22621.1 (Ebbighausen and Korn 2009 Coll.); illustrated here in Fig. 11b .

Type locality and horizon: Madène el Mrakib (Anti-Atlas); Procymaclymenia beds (late Famennian).

Material: 252 specimens with a maximum conch diameter of 45 mm.

Diagnosis: Species of Procymaclymenia with thinly discoidal conch in the adult stage (ww / dm = 0.28); whorl cross section compressed (ww / wh = 0.60). Conch shape in the intermediate stage (10 mm dm) thinly discoidal and subevolute (ww / dm = 0.30; uw / dm = 0.32). Umbilical wall steep in the adult stage, flanks subparallel, venter rounded or slightly flattened and separated from the flanks by a subangular margin. Ornament with very fine biconvex growth lines, steinkern without constrictions.

Discussion: Procymaclymenia ebbighauseni differs from P. inflata ( Czarnocki, 1989) and P. pudica ( Czarnocki, 1989) from the Holy Cross Mountains in the smooth steinkern, which in the other two species displays strong constrictions. Furthermore, the other two species possess riblets around the umbilicus, which are very faint in P. ebbighauseni .

The new species was utilised by Becker et al. (2002) as an index for the “ Cymaclymenia pudica Zone ”, which has a position between the “ Platyclymenia annulata Zone ” and the “ Sporadoceras orbiculare Zone ”. The authors provide a list of co-occurring species, predominantly platyclymeniids and prionoceratids. Recent bed-by-bed research, however, has demonstrated that Procymaclymenia ebbighauseni occurs higher in the section than postulated by Becker et al. (2002); a co-occurrence of typical species of the Platyclymenia annulata Zone and P. ebbighauseni does not exist. In the section at Madène el Mrakib, P. ebbighauseni has its lowest occurrences immediately below the oldest horizon with “ Sporadoceras orbiculare ”.

Figures

Figure 11. Procymaclymenia ebbighauseni n. sp. from the Anti-Atlas of Morocco; all × 1.0. (A) Paratype MB.C.22619.1 (Ebbighausen and Korn 2009 Coll.) from Madène el Mrakib. (B) MB.C.22621.1 (Ebbighausen and Korn 2009 Coll.) from Madène el Mrakib. (C) Paratype MB.C.22665.1 (Korn 1995 Coll.) from El Atrous. (D) Paratype MB.C.22665.2 (Korn 1995 Coll.) from El Atrous. (E) Paratype MB.C.22620.2 (Ebbighausen and Korn 2009 Coll.) from Madène el Mrakib. (F) Paratype MB.C.22620.1 (Ebbighausen and Korn 2009 Coll.) from Madène el Mrakib. (G) Paratype MB.C.22622.1 (Ebbighausen and Korn 2009 Coll.) from Madène el Mrakib.

Figure 12. Cross sections (A–E; all × 1.5) and ontogenetic trajectories (F–I) of Procymaclymenia ebbighauseni n. sp. from Madène el Mrakib (Anti-Atlas of Morocco). (A) Paratype MB.C.22619.2 (Ebbighausen and Korn 2009 Coll.). (B) Paratype MB.C.22619.4 (Ebbighausen and Korn 2009 Coll.). (C) Paratype MB.C.22639 (Korn 1998 Coll.). (D) Paratype MB.C.22619.5 (Ebbighausen and Korn 2009 Coll.). (E) Paratype MB.C.22619.3 (Ebbighausen and Korn Coll.). (F) Conch width index (ww /dm). (G) Umbilical width index (ww/ wh). (H) Whorl width index (uw / dm). (I) Whorl expansion rate (WER).