Sonninia (Sonninia) Douvillé, 1879

Sandoval, José, 2022, Sonniniidae Ammonitina, Middle Jurassic from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis, Geodiversitas 44 (27), pp. 801-851 : 809-810

Subgenus Sonninia (Sonninia) Douvillé, 1879 [M] & [m]?

TYPE SPECIES. — Waagenia propinquans Bayle, 1878 ( Bayle 1878: pl. 84, fig. 1 [OD]) (LT designated by Gillet 1937: 29).

DESCRIPTION

Macroconchs of medium to large size, planulate slightly involute to evolute. The whorl section varies from subquadrangular to compressed ogival throughout its ontogenetic development and the ventral area has a hollow, moderately high to high keel. The innermost whorls are usually smooth.Subsequently, more or less irregular ribs appear below the umbilical edge, some dividing the lower part of the flank, near the umbilical rim, as well as irregularly developed tubercles, which are usually located in the division of the ribs.Tubercles fade on middle whorls, and ribs fade on outer whorls, which become smooth, more involute, and compressed. The septal suture is relatively complex, with a ramified deep L, and slightly retracted U2-U5 lobes.

The S. ( Sonninia ) microconchs [m] have not yet been clearly identified, and thus are difficult to distinguish from those of Witchellia . Some of the “ Pelekodites ” forms as “ P. ” schlumbergeri ( Haug, 1893) and “ Maceratites ” forms, which occur frequently in the upper part of the Laeviuscula Zone and in the Propinquans Zone in the Subbetic domain, most likely represent the dimorphic microconchs of S. ( Sonninia ).

REMARKS

Some species of S. ( Sonninia ) can strongly resemble S. (Euhoploceras), but the latter is more evolute and has a massive subquadrate or subrectangular whorl section and rursiradiate ribbing. S. ( Papilliceras ) is similar in almost all the characters, but has a row of well-aligned midlateral tubercles, which differentiates it from S. ( Sonninia ). Some S. ( Sonninia ) species may have similarities with Sonninites Buckman , but this genus is generally more involute, has less marked ribbing, and the tubercles, if present, are restricted to the innermost whorls. Witchellia , another related genus, has a more planulate whorl section, lacks tubercles, or these are reduced to innermost whorls, and has a simpler septal suture.

DISTRIBUTION

In agreement with Howarth (2013, in Treatise: 15), the stratigraphic range of S. ( Sonninia ) is limited to the Propinquans Zone. However, some species traditionally included in Sonninia , such as S. (S.) corrugata (J. de C. Sowerby, 1824) or S. (S.) micracanthica (Buckman, 1925) , are frequently cited in the Laeviuscula Zone (see also Dietze et al. 2019). Other species [ S. (S.) patella ( Waagen, 1867) , S. (S.) carinodisca (Quenstedt, 1886) , S. (S.) furticarinata (Quenstedt, 1858) , “ S. (S.)” disciformis Dorn, 1935] have been cited in the lowermost part of the Humphriesianum Zone (Fernández-López 1985; De Baets et al. 2008; Dietze et al. 2008, 2013). The genus is found in Europe, North Africa ( Atlas Mountains ), Madagascar, the Caucasus, Azerbaijan, Iran, China (Tibet), Japan, western Australia, United States (Alaska, Oregon), Chile, and Argentina. Subbetic specimens occur in the upper part of the Laeviuscula Zone and Propinquans Zone from various localities.