Domatoceras Hyatt 1891

Genus Domatoceras Hyatt, 1891 Type species Domatoceras umbilicatum Hyatt, 1891; original designation. Diagnosis Genus of the family Domatoceratidae with a subinvolute to evolute conch. High to extremely high coiling rate; whorl profile usually weakly compressed. Venter flattened or weakly concave, flanks usually flattened and slightly convergent; umbilical margin rounded or angular. Without sculpture except for small ventrolateral tubercles in some species. Suture line with small and shallow external lobe and broadly rounded lateral lobe; without annular process. Included Carboniferous species North America (Meek & Worthen 1865; Worthen & Meek 1875; Gurley 1883; Hyatt 1891; Miller & Owen 1934; Sturgeon & Miller 1948; Tucker 1976; Tucker & Mapes 1978; Sturgeon et al. 1982; Niko & Mapes 2016b; Niko et al. 2022): Nautilus Lasallensis Meek & Worthen, 1865, Kasimovian, Illinois; Nautilus (Discites) highlandensis Worthen in Worthen & Meek, 1875, Moscovian, Ohio; Discites Toddanus Gurley, 1883, Kasimovian, Missouri; Domatoceras umbilicatum Hyatt, 1891, Moscovian, Kansas; Domatoceras williamsi Miller & Owen, 1934, Moscovian, Ohio; Domatoceras obsoletum Sturgeon, 1946, Moscovian, Ohio; Domatoceras shepherdi Sturgeon, 1948, Moscovian, Ohio; Domatoceras wortheni Tucker, 1976, Kasimovian, Illinois; Domatoceras texanum Tucker & Mapes, 1978, Kasimovian, Texas; Domatoceras oreskovichi Sturgeon, Windle, Mapes & Hoare, 1982, Moscovian, Ohio; Domatoceras collinsvillense Niko & Mapes, 2016, Moscovian, Oklahoma; Domatoceras tuckeri Niko, Mapes & Seuss, 2022, Kasimovian, Texas. South China (Ruan & Zhou 1987): Domatoceras quadratum Ruan & Zhou, 1987, Bashkirian, Ningxia. West Russia (Tzwetaev 1888, 1898; Shimansky 1967): Nautilus podolskensis Tzwetaev, 1888, Moscovian, Moscow Basin; Nautilus mosquensis Tzwetaev, 1898, Moscovian, Moscow Basin; Domatoceras (Domatoceras) magister Shimansky, 1967, Moscovian, Moscow Basin. Included Permian species Urals (Leonova & Shchedukhin 2020): Domatoceras bashkiricum Leonova & Shchedukhin, 2020, Asselian or Sakmarian, South Urals; Domatoceras sterlitamakense Leonova & Shchedukhin, 2020, Asselian or Sakmarian, South Urals. Transcaucasia and Iran (Abich 1878; Shimansky 1965; this paper): Nautilus parallelus Abich, 1878, Wuchiapingian, Azerbaijan; Nautilus convergens Abich, 1878, Wuchiapingian, Azerbaijan; Domatoceras gracile Shimansky, 1965, Wuchiapingian, Azerbaijan; Domatoceras atypicum Shimansky, 1965, Wuchiapingian, Azerbaijan; Domatoceras multituberculatum Korn & Ghaderi, 2025, Wuchiapingian, NW Iran; Domatoceras canonium sp. nov., Wuchiapingian, Central Iran; Domatoceras ocomphalum sp. nov., Wuchiapingian, Central Iran; Domatoceras myloide sp. nov., Wuchiapingian, Central Iran. South China (Zhao et al. 1978): Domatoceras guangxiense Zhao, Liang & Zheng, 1978, Changhsingian, Guangxi. Japan (Ehiro & Takizawa 1989): Domatoceras ogatsuense Ehiro & Takizawa, 1989, Wuchiapingian, Kitakami Massif. Remarks The species of the genus Domatoceras have a very similar conch morphology from the Moscovian to the Changhsingian, suggesting a very conservative evolutionary lineage. Shimansky (1967) also included some Serpukhovian species in Domatoceras, but these differ from the typical representatives of the genus in that they have a wider conch and lack a subangular or angular ventrolateral shoulder. These stratigraphically older species may belong to Epidomatoceras Turner, 1954. The similarity in the morphology of the conchs, the virtual absence of sculptural elements and the fact that the suture line depends essentially on the shape of the whorl profile make it difficult to distinguish the species within Domatoceras. Another difficulty is that the species of the genus occur in two phases: the first phase extends from the Moscovian to the Asselian–Sakmarian boundary, and the second phase extends from the Wuchiapingian to the Changhsingian. It should be noted, however, that of the Late Permian species, about ten are known from the Wuchiapingian and only one from the Changhsingian. Apparently, no species are known from the long interval between the Sakmarian and the Capitanian. Some species from the Kungurian and Roadian, which were placed under Domatoceras by Miller & Unklesbay (1942) and Miller & Youngquist (1949), have been assigned to other genera such as Penascoceras by Ruzhencev & Shimansky (1954).