Alternacanthoceras subgen. novo (Ammonoidea) and some remarks on other Cenomanian representatives of the genus Acanthoceras Neumagr, 1875

Abstract

A new subgenus Alternacanthoceras subgen. novo is recognized within the ammonoid genus Acanthoceras Neumayr, 1875, to include large acanthoceratids with long and short ribs alternating at all the ontogenetic stages. A comparative analysis is given of the nominative subgenus Acanthoceras and the subgenus Guerangericeras Thomel, 1972. The species Acanthoceras (Alternacanthoceras) jukesbrownei (Spath, 1926) recognized for the type species of Alternacanthoceras subgen. novo is here described from the Middle Cenomanian of the Subherzynian basin.