Genus Aphelaeceras Hyatt, 1884

Type species

Nautilus (Discites) disciformis Meek & Worthen, 1873; subsequent designation by Miller & Garner (1953).

Diagnosis

Genus of the family Trigonoceratidae with subevolute to evolute conch; whorls slightly impressed; whorl profile compressed, venter concave and bordered by an angular ventrolateral shoulder, flanks convex, convergent; umbilical margin rounded or subangular. Suture line with shallow external and lateral lobes. Siphuncle small with subcentral position (after Kummel 1964; emended).

Included species

Nautilus (Discites) disciformis Meek & Worthen, 1873, Illinois; Nautilus (Discites) mutabilis M’Coy, 1844, Ireland; Nautilus (Discites) trochlea M’Coy, 1844, Ireland; Aphelaeceras arkansanum Gordon, 1965, Arkansas; Nautilus difficilis de Koninck, 1878, Belgium; Nautilus discoideus de Koninck, 1878, Belgium; Nautilus exaratus de Koninck, 1878, Belgium; Discitoceras discus Sowerby, 1813, Ireland; Discites Hibernicus Foord & Crick, 1893, Ireland; Aphelaeceras azzelmattiense sp. nov., Algeria.