Upper Carboniferous--Permian stratigraphy and fusulinids...

Genus Ultradaixina Davydov, 1982

Ultradaixina bosbytauensis distincta

Leven, n. subsp.
Plate 5, figs 7-9, 11, 13, 14, 18

Etymology.

[75] Distincta - distinct.

Holotype.

[76] GIN 4781/77. Axial section. Iran, Anarak, Zaladou Formation; Carboniferous, Pennsylvanian, latest Gzhelian.

Material.

[77] 10 axial and subaxial sections.

Description.

[78] Shell of moderate but variable size, fusiform to inflated fusiform, with convex lateral slopes and bluntly pointed poles. Adult shells of 4.5 to 5 volutions measure 5.0 mm to 7.2 mm in length and 2.5 mm to 3.9 mm in diameter, form ratio 1.8 to 2.4. First 1 to 2 volutions constitute tightly coiled juvenarium, followed by more or less abrupt expansion into loosely coiled adult stage. Spirotheca composed of tectum and thin alveolar keriotheca, 0.1 mm to 0.125 mm thick in outer whorls. Septa irregularly fluted from pole to pole or only slightly wavy across middle of shell. Proloculus medium-sized, its outside diameter 0.15 mm to 0.21 mm. Tunnel low or narrow. Chomata narrow and developed only in juvenarium. Axial fillings are absent.

Discussion.

[79] Ultradaixina bosbytauensis distincta n. subsp. is similar to Ultradaixina bosbytauensis bosbytayensis (Bensh) but differs from it in a slightly isolated juvenarium, presence of chomata, and generally in lesser size.

Distribution and age.

[80] Iran, Precaspian syneclise; Carboniferous, Pennsylvanian, latest Gzhelian.

Occurrence.

[81] Iran, Anarak, Zaladou Formation, Samples P3, P6, C1, C27, AC29.