Epistroboceratidae, Korn, 2025

Family Epistroboceratidae fam. nov.

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Fig. 15 View Fig

Type genus

Epistroboceras Turner, 1954 View in CoL .

Diagnosis

Family of the superfamily Subclymenioidea with usually subevolute conch. Whorl overlap very small. Whorl profile ranging from moderately depressed to moderately compressed, usually with polygonal shape. Venter usually flat. Sculpture with coarse longitudinal ridges and grooves. Suture line with broadly rounded lobes and saddles, strongly dependent on the shape of the whorl profile.

Etymology

The subfamily name refers to the type genus.

Included genera

Stroboceras Hyatt, 1884 (Tournaisian to Bashkirian; 15 species).

Epistroboceras Turner, 1954 (Tournaisian to Serpukhovian; 18 species).

Imonautilus Niko & Mapes, 2007 (Serpukhovian; 1 species).

Trilobitoceras Korn & Bockwinkel, 2022 (Tournaisian; 2 species).

Remarks

The genera Stroboceras and Epistroboceras have been placed in different families or subfamilies by various authors. Miller & Garner (1953) placed Stroboceras in the family Rineceratidae ; they derived Stroboceras from Discitoceras : “ Discitoceras most probably also gave rise to Stroboceras by certain of its longitudinal ridges becoming very large at the expense of others. Stroboceras … ” ( Miller & Garner 1953: 116). Turner (1954) revised Stroboceras and proposed the new genus Epistroboceras ; he placed both in the family Triboloceratidae .

Shimansky (1962) placed Stroboceras and Epistroboceras in the subfamily Thrincoceratidae and later changed his mind ( Shimansky 1967: 134) to assign both genera in the Trigonoceratinae . Earlier, Kummel (1964) had already included both genera in the Trigonoceratidae , without distinguishing between subfamilies. Turner (1965) included Stroboceras and Epistroboceras in the Thrincoceratinae .

Dzik (1984: 173–174) had a different concept and considered the genera Stroboceras and Epistroboceras to be not closely related and placing Stroboceras in the Grypoceratidae and Epistroboceras (as a junior synonym of Aphelaeceras Hyatt, 1884 ) in the Phacoceratidae . Histon (1999) followed Kummel (1964) and considered Epistroboceras to be a representative of the Trigonoceratidae .

Here, the stroboceratids are distinguished as a separate family, characterised by the presence of prominent longitudinal ridges, which in many species cause a polygonal outline to the whorl profile ( Fig. 15 View Fig ). These ridges can be seen as a transfer of the early juvenile sculpture to the adult conch. During phylogeny, these ridges have been secondarily reduced, and in the families Subclymeniidae and Phacoceratidae they are present only in the juvenile stage. Therefore, these are also included in the superfamily Grypoceratoidea .