Sonniniidae (Ammonitina, Middle Jurassic) from Southern Spain: taxonomic, biostratigraphical and palaeobiogeographical analysis

A taxonomic and biostratigraphical revision of the sonniniids is presented using bibliographic data and mainly the material collected in the Subbetic domain (Betic Cordillera, southern Spain). The Sonniniidae are shown to range from the uppermost Aalenian (Concavum Zone, Limitatum Subzone) to the Lower Bajocian (Humphriesianum Zone, Romani Subzone). Subbetic Sonniniidae are represented by the subfamilies: Sonniniinae, with the genera Sonninia and the subgenera S. (Sonninia), S. (Euhoploceras), S. (Papilliceras), and Sonninites; and Witchelliinae, with the genera Witchellia and Dorsetensia. The taxa Sonninia (Alaskinia), Shirbuirnia, and Pseudoshirbuirnia have not been recorded so far in the Subbetic domain. Taxonomical analyses indicate that the genus Dorsetensia, classically included in the Sonniniinae (Howarth 2013: Treatise), should be transferred to Witchelliinae, whereas the genera Asthenoceras, Fontannesia, and Newmarracarroceras (Witchelliinae in Treatise) appear to represent the latest Grammoceratinae instead of primitive Witchelliinae. Dimorphism and possible polymorphism are present in the Subbetic Sonniniidae. Of the 31 sonniniid morphospecies described, 22 are macroconchs and nine are microconchs. Two new species of Witchellia are nominated and described: W. companyi n. sp., evolute with wide and shallow umbilicus, rectangular compressed section and fine keel; and W. striata n. sp., relatively involute, shallow umbilicus, compressed rectangular section with a very shallow depression in the lower part of the flanks, fine falcate ribbing that fades, being replaced by bundles of striae in the body-chamber.