Cymaclymenia serotina, 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 : 22

Cymaclymenia serotina n. sp.

Figure 24

Derivation of name: After Lat. serotinus, -a, -um (adj.) = delayed; because of the late stratigraphic occurrence.

Holotype: Specimen MB.C.22605.1 (Korn 1995 Coll.); illustrated here in Fig. 24a .

Type locality and horizon: Erfoud (Anti-Atlas), immediately east of the Muslim cemetery on the eastern side of the Ziz Valley; bed 55 of Korn (1999), Parawocklumeria paradoxa Assemblage (late Famennian).

Material: 10 specimens with a maximum conch diameter of 45 mm.

Diagnosis: Species of Cymaclymenia with thinly discoidal conch in the adult stage (ww / dm = 0.30); whorl cross section weakly compressed (ww / wh = 0.65). Conch shape in the intermediate stage (10 mm dm) thinly discoidal and subinvolute (ww / dm = 0.33; uw / dm = 0.25–0.30). Umbilical wall oblique in the adult stage, flanks moderately converging, venter rounded. Ornament with almost smooth and extremely fine biconvex growth lines, without riblets.

Discussion: C. serotina differs from nearly all other species of the genus in the very faint conch ornament. The species differs from Cymaclymenia formosa and the other Moroccan species with slender conchs by the extremely fine ornament, which consists of very delicate growth lines. In this respect it is similar to C. lambidia , but this species has a stouter conch.

Figures

Figure 24. Cymaclymenia serotina n. sp. from the Anti-Atlas of Morocco; all × 1.0. (A) Holotype MB.C.22605.1 (Korn 1995 Coll.) from Erfoud. (B) Paratype MB.C.22605.2 (Korn 1995 Coll.) from Erfoud. (C) Paratype MB.C.22605.3 (Korn 1995 Coll.) from Erfoud.