Foraminifera name details
Pseudoammodiscus diadema subsp. irregularis (Golubtsov, 1957) †
1304537 (urn:lsid:marinespecies.org:taxname:1304537)
accepted > unreplaced junior homonym (Primary junior homonym of Ammodiscus irregularis Grzybowski, 1898)
Subspecies
Ammodiscus diadema var. irregularis Golubtsov, 1957 † · unaccepted (Opinion of Hance, Hou and Vachard...)
Opinion of Hance, Hou and Vachard (2011)
marine, brackish, fresh, terrestrial
fossil only
(of Ammodiscus diadema var. irregularis Golubtsov, 1957 †) Golubtsov, V. K. (1957). Стратиграфия и фораминиферы визейского яруса Припятского - Stratigraphy and Foraminifera of the Visean Series of the Pripyat Arch. <em>Палеонтология и стратиграфия БССР Akad Nauk Beloruss SSR, Inst. Geol. Nauk, Sbornik.</em> 2: 44-191., available online at https://books.google.pt/books?id=c_E3LFsaaoUC
page(s): pp. 104-105, pl. 1, figs. 17-18 (holotype fig. 17). [details] Available for editors
[request]
page(s): pp. 104-105, pl. 1, figs. 17-18 (holotype fig. 17). [details] Available for editors
[request]
Description Holotype in the collection of the Institute of Geophysics of the Academy of Sciences of the Byelorussian SSR, No. 2/37....
Description Holotype in the collection of the Institute of Geophysics of the Academy of Sciences of the Byelorussian SSR, No. 2/37. Gomel Region, Kopatkevichi District; Mikhailovsky Horizon. Diagnosis. The shell is planospiral, compressed, the spiral unfolds unevenly. The proloculus is wide, slightly deepened. The spiral suture is clearly visible in the last whorls.
Description. The shell is planospiral, compressed, consists of an initial spherical chamber and a long tubular second chamber, curled more or less in one plane. The proloculus is wide, slightly deepened. The peripheral edge is widely rounded. The surface is slightly uneven; the spiral suture is clearly visible in the last one or two whorls. The number of whorls is 3-4, but usually specimens with 3 whorls predominate. The planes of winding of individual whorls of the spiral are slightly turned to each other at a very small angle. Sometimes the first two whorls are wound in one plane and slightly shifted relative to the last two whorls, which are also wound in one plane. The spiral unfolds slowly in the initial whorls, and accelerates sharply in the last two whorls, which are very wide and high compared to the first two whorls. The height of each whorl varies slightly throughout its length due to the not quite regular tubular chamber. All whorls are completely non-enveloping [evolute]. The wall is dark, uniform, calcareous, fine-grained; its thickness does not exceed 10-12 μ in the last whorl, often only 5-8 μ. No thickening of the walls on the lateral surfaces is observed. The aperture is formed by the open end of the tubular chamber.
Dimensions: The diameter of the shell does not exceed 0.34 mm, and in specimens with 3 whorls the diameter is 0.23-0.30 mm. The thickness of the last whorl varies from 0.075 to 0.085 mm. The height of the last whorl is slightly less than its thickness and is usually equal to 0.050-0.060 mm. Thus, the tubular chamber is slightly flattened parallel to the axis of coiling. The initial chamber is large, usually larger than the height and thickness of the first two whorls, its diameter is about 0.040 mm and is never less than 0.03 mm.
Comparison. In the nature of the spiral winding, large initial chamber, rather flat proloculus and thin wall, the described forms are close to Ammodiscus diadema Brazhn., differing from the latter in slightly larger sizes, a slightly different ratio of the thickness and height of the last whorl, uneven unfolding of the spiral. These differences do not allow us to identify the described forms with A. diadema. Due to the characteristic unfolding of the spiral, the described forms can be distinguished into a new variety A. diadema Brazhn. irregularis var. n. Characteristic features of this variety are slightly recessed navels, large initial chamber, thin walls, uneven spiral development, recessed spiral suture and more or less irregular spiral winding. These features distinguish A. diadema var. irregularis from all other Ammodiscus.
Location. Kopatkevichi area. Single form, only 10 well-preserved specimens have been found. Distribution and age. Found in the Aleksinsky and Mikhailovsky horizons of the Visean stage. [details]
Description. The shell is planospiral, compressed, consists of an initial spherical chamber and a long tubular second chamber, curled more or less in one plane. The proloculus is wide, slightly deepened. The peripheral edge is widely rounded. The surface is slightly uneven; the spiral suture is clearly visible in the last one or two whorls. The number of whorls is 3-4, but usually specimens with 3 whorls predominate. The planes of winding of individual whorls of the spiral are slightly turned to each other at a very small angle. Sometimes the first two whorls are wound in one plane and slightly shifted relative to the last two whorls, which are also wound in one plane. The spiral unfolds slowly in the initial whorls, and accelerates sharply in the last two whorls, which are very wide and high compared to the first two whorls. The height of each whorl varies slightly throughout its length due to the not quite regular tubular chamber. All whorls are completely non-enveloping [evolute]. The wall is dark, uniform, calcareous, fine-grained; its thickness does not exceed 10-12 μ in the last whorl, often only 5-8 μ. No thickening of the walls on the lateral surfaces is observed. The aperture is formed by the open end of the tubular chamber.
Dimensions: The diameter of the shell does not exceed 0.34 mm, and in specimens with 3 whorls the diameter is 0.23-0.30 mm. The thickness of the last whorl varies from 0.075 to 0.085 mm. The height of the last whorl is slightly less than its thickness and is usually equal to 0.050-0.060 mm. Thus, the tubular chamber is slightly flattened parallel to the axis of coiling. The initial chamber is large, usually larger than the height and thickness of the first two whorls, its diameter is about 0.040 mm and is never less than 0.03 mm.
Comparison. In the nature of the spiral winding, large initial chamber, rather flat proloculus and thin wall, the described forms are close to Ammodiscus diadema Brazhn., differing from the latter in slightly larger sizes, a slightly different ratio of the thickness and height of the last whorl, uneven unfolding of the spiral. These differences do not allow us to identify the described forms with A. diadema. Due to the characteristic unfolding of the spiral, the described forms can be distinguished into a new variety A. diadema Brazhn. irregularis var. n. Characteristic features of this variety are slightly recessed navels, large initial chamber, thin walls, uneven spiral development, recessed spiral suture and more or less irregular spiral winding. These features distinguish A. diadema var. irregularis from all other Ammodiscus.
Location. Kopatkevichi area. Single form, only 10 well-preserved specimens have been found. Distribution and age. Found in the Aleksinsky and Mikhailovsky horizons of the Visean stage. [details]
Hayward, B.W.; Le Coze, F.; Vachard, D.; Gross, O. (2025). World Foraminifera Database. Pseudoammodiscus diadema subsp. irregularis (Golubtsov, 1957) †. Accessed at: https://www.marinespecies.org/foraminifera/aphia.php?p=taxdetails&id=1304537 on 2025-05-09
Date
action
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original description
(of Ammodiscus diadema var. irregularis Golubtsov, 1957 †) Golubtsov, V. K. (1957). Стратиграфия и фораминиферы визейского яруса Припятского - Stratigraphy and Foraminifera of the Visean Series of the Pripyat Arch. <em>Палеонтология и стратиграфия БССР Akad Nauk Beloruss SSR, Inst. Geol. Nauk, Sbornik.</em> 2: 44-191., available online at https://books.google.pt/books?id=c_E3LFsaaoUC
page(s): pp. 104-105, pl. 1, figs. 17-18 (holotype fig. 17). [details] Available for editors [request]
new combination reference Hance, L.; Hou, H.; Vachard, D. (2011). Upper Famennian to Visean foraminifers and some carbonate microproblematica from South China – Hunan, Guangxi and Guizhou . <em>Beijing Geological Publishing House: Beijing.</em> 1-359. [details] Available for editors [request]
new combination reference Kobayashi, F.; Vachard, D. (2022). Carboniferous foraminifers and biostratigraphy of lower Akiyoshi Limestone (Japan). <em>Revue de Paléobiologie.</em> 41(2): 99-239., available online at https://doi.org/10.5281/zenodo.6858352 [details] Available for editors [request]
page(s): pp. 104-105, pl. 1, figs. 17-18 (holotype fig. 17). [details] Available for editors
[request]new combination reference Hance, L.; Hou, H.; Vachard, D. (2011). Upper Famennian to Visean foraminifers and some carbonate microproblematica from South China – Hunan, Guangxi and Guizhou . <em>Beijing Geological Publishing House: Beijing.</em> 1-359. [details] Available for editors
[request]new combination reference Kobayashi, F.; Vachard, D. (2022). Carboniferous foraminifers and biostratigraphy of lower Akiyoshi Limestone (Japan). <em>Revue de Paléobiologie.</em> 41(2): 99-239., available online at https://doi.org/10.5281/zenodo.6858352 [details] Available for editors
[request]From editor or global species database
Description Holotype in the collection of the Institute of Geophysics of the Academy of Sciences of the Byelorussian SSR, No. 2/37. Gomel Region, Kopatkevichi District; Mikhailovsky Horizon. Diagnosis. The shell is planospiral, compressed, the spiral unfolds unevenly. The proloculus is wide, slightly deepened. The spiral suture is clearly visible in the last whorls. Description. The shell is planospiral, compressed, consists of an initial spherical chamber and a long tubular second chamber, curled more or less in one plane. The proloculus is wide, slightly deepened. The peripheral edge is widely rounded. The surface is slightly uneven; the spiral suture is clearly visible in the last one or two whorls. The number of whorls is 3-4, but usually specimens with 3 whorls predominate. The planes of winding of individual whorls of the spiral are slightly turned to each other at a very small angle. Sometimes the first two whorls are wound in one plane and slightly shifted relative to the last two whorls, which are also wound in one plane. The spiral unfolds slowly in the initial whorls, and accelerates sharply in the last two whorls, which are very wide and high compared to the first two whorls. The height of each whorl varies slightly throughout its length due to the not quite regular tubular chamber. All whorls are completely non-enveloping [evolute]. The wall is dark, uniform, calcareous, fine-grained; its thickness does not exceed 10-12 μ in the last whorl, often only 5-8 μ. No thickening of the walls on the lateral surfaces is observed. The aperture is formed by the open end of the tubular chamber.
Dimensions: The diameter of the shell does not exceed 0.34 mm, and in specimens with 3 whorls the diameter is 0.23-0.30 mm. The thickness of the last whorl varies from 0.075 to 0.085 mm. The height of the last whorl is slightly less than its thickness and is usually equal to 0.050-0.060 mm. Thus, the tubular chamber is slightly flattened parallel to the axis of coiling. The initial chamber is large, usually larger than the height and thickness of the first two whorls, its diameter is about 0.040 mm and is never less than 0.03 mm.
Comparison. In the nature of the spiral winding, large initial chamber, rather flat proloculus and thin wall, the described forms are close to Ammodiscus diadema Brazhn., differing from the latter in slightly larger sizes, a slightly different ratio of the thickness and height of the last whorl, uneven unfolding of the spiral. These differences do not allow us to identify the described forms with A. diadema. Due to the characteristic unfolding of the spiral, the described forms can be distinguished into a new variety A. diadema Brazhn. irregularis var. n. Characteristic features of this variety are slightly recessed navels, large initial chamber, thin walls, uneven spiral development, recessed spiral suture and more or less irregular spiral winding. These features distinguish A. diadema var. irregularis from all other Ammodiscus.
Location. Kopatkevichi area. Single form, only 10 well-preserved specimens have been found. Distribution and age. Found in the Aleksinsky and Mikhailovsky horizons of the Visean stage. [details]
From editor or global species database
Image from synonym