Sonninia Buckman 1920

Sonninia (Papilliceras?) sp. [M]

(Fig. 9D)

MATERIAL EXAMINED. — JAC11. R.61 and JAC22.6.13.

MEASUREMENTS. — See Table 8.

DESCRIPTION

The best-preserved specimen consists of a little more than three-quarters of whorl, including the end of the PH and the BC. The second specimen preserves just over a third of a whorl. These rather small macroconchs are relatively evolute and have moderate whorl expansion. The section is compressed subrectangular with a subvertical umbilical wall, rounded umbilical edge, faintly convex flanks, and a rounded ventral area with a high hollow keel. The ribs, well marked throughout ontogeny, are radial and bend forward near the venter.In the PH, between every 3 to 5 non-tuberculate ribs, a stronger one appears with a well-developed mid-lateral tubercle; subsequently the ribs become progressively uniform, all bearing less developed midlateral tubercles. Septal sutures are not preserved.

REMARKS

The described specimens show intermediate characters between S. (Euhoploceras) and S. (Papilliceras), but the presence of typical mid-lateral tubercles has led to their being included, although with doubts, in Papilliceras. The most similar form may be “ Sonninia ” mayeri (Waagen, 1867), which has been considered synonymous to S. (Euhoploceras) polyacantha (Waagen, 1867) by Schlegelmilch (1985) and as a nomen dubium by Dietze et al. (2005: 35). However, German specimens are much larger and somewhat more evolute.

DISTRIBUTION

The HT of the most similar species, S. (E.) polyacantha, comes from the Laeviuscula Zone, Trigonalis Subzone (adicra α or adicra β horizon) of Gingen/Fils, Germany (Sadki & Dietze 2021). The only Subbetic specimen sampled in situ is slightly older and comes from the Ovale Zone of the Barranco del Almendro Gordo section (JAC22), Sierra de Alta Coloma area, Campillo de Arenas (Jaén Province).