Sonninia (Euhoploceras) cf. polyacantha ( Waagen, 1867 )

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 816

Sonninia (Euhoploceras) cf. polyacantha ( Waagen, 1867) [M] ( Figs 7N ; 8A )

MATERIAL EXAMINED. — JAQ 1.3.1.

MEASUREMENTS. — See Table 6.

DESCRIPTION

The only available specimen is an incomplete, somewhat eroded PH. The internal mould of the PH measures 88 mm in diameter with the inner whorls, which are not preserved. The shell is a relatively evolute discoidal platycone. The whorl section is compressed subrectangular with a subvertical umbilical wall, rounded umbilical edge, and slightly convex, almost flat flanks. The venter is rounded, while the keel is hollow and partially preserved only in the first quarter of the last preserved whorl. The ribs, first slightly uneven, and then uniform, arise near the umbilical edge, radial and not strong, and fade on the upper part of the flank, where they lean slightly forward. Some of the stronger ribs appear to support small lateral tubercles. The septal suture ( Fig. 8A ) is typical of S. (Euhoploceras), being sharply divided with a deep L and slightly retracted umbilical lobes.

REMARKS

In this subbetic specimen the intermediate whorls closely resemble those of the HT of S. (E.) polyacantha ( Waagen, 1867) , (refigured in Dorn 1935: pl. 9, fig. 1; Schlegelmilch 1985: pl. 17, fig. 2; Sadki & Dietze 2021: 4, text-fig. 7), the two specimens coinciding in the type of coiling, section, and radial ribbing, but the ribs are much weaker in the former.

DISTRIBUTION

The HT of S. (E.) polyacantha comes from the Laeviuscula Zone (Trigonalis Subzone) of Gingen/Fils, southern Germany ( Dietze et al. 2005; Sadki & Dietze 2021). The Subbetic specimen comes from the Laeviuscula Zone of the Barranco de Agua Larga section, Noalejo (Jaén Province).

Figures

FIG. 7. — A-D, Sonninia (Sonninia) propinquans (Bayle, 1878) [M]: A, JAC13.R.1, Propinquans Zone, Sierra de Alta Coloma (JAC13 section); B, D, JAC11.8.8, JAC11.8.9, Propinquans Zone, Patella Subzone, Sierra de Alta Coloma (JAC11 section); C, JAC21.16.4, Propinquans Zone, Patella Subzone, Sierra de Alta Coloma (JAC21 section); E, Sonninia (Sonninia) patella (Waagen, 1867) [M], JAC20.(7-6).5, Propinquans Zone, Patella Subzone, Caminno de Casa Blanca section; F, G, Sonninia (Sonninia) falcata Haug, 1893 [M?], non Quenstedt, 1886: F, JAC21.17.5, Propinquans Zone, Patella Subzone, Sierra de Alta Coloma (JAC21 section); G, JCH.2.2, Propinquans Zone, Charilla, Jaén province (JCH section); H-K, Sonninia (Sonninia) corrugata (J. de C. Sowerby, 1824) [M]: H, I, JAC21.12.5,

FIG. 8. — Septal suture of some Subbetic sonniniids: A, Sonninia (Euhoploceras) cf. polyacantha (Waagen, 1867) [M], specimen JAQ1.3.1; B, Witchellia albida (Buckman, 1926) [M], specimen JAC13.R.3; C, Witchellia hyalina (Buckman, 1924) [M], specimen JAC11.8.21; D, E, Witchellia companyi n. sp. [M], specimens JAC11.8.22 and JAC11.8.16 (HT); F, Dorsetensia liostraca Buckman, 1892 [M], specimen JGa8.32.4. Scale bars: 5 mm.