Catalog - Alloglobigerinoides

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Alloglobigerinoides

Citation: Alloglobigerinoides Huang 1986

Type species: Globigerina conglobata Brady 1879

Test free. trochospiral; chambers globular to ovate; sutures depressed. radial; wall calcareous, coarsely perforate, hispid or spinose; primary aperture interiomarginal, umbilical, as in Globigerina, umbilical aperture covered by the final chamber of the adult, which has smaller econdary apertures around its lower margin above the single intercameral suture; wall of last formed umbilical chamber is similar in structure to the primary wall coarsely perforated; small secondary sutural apertures on the spiral side, as in Globigerinoides which may not be covered by sutural bullae.

Remarks. - Alloglobigerinoides, new genus morphologically resembles Globigerinoita Bronnimann, 1952, in having Globigerinoides test and umbi lical chamber but d iffers in lacking the sutural bullae covering the seconda ry apertures of spiral side. In Alloglobigerinoides the early stage is similar to Globigerina d'Orbigny and later to

-type test with umbilical chamber.

Alloglobigerinoides differs from Globigerinoides Cushman in the absence of an umbilical primary aperture in the last ontogenetic stage which covered by the last formed umbilical chamber. The umbilical chamber has smaller sutural secondary apertures and as a rule placed symmetrically above the single intercameral suture (pl. 2, fig. 3; see Huang. 1986), which may not be covered by bullae.

The relationship between the new genus Alloglobigerinoides and the genus Globigerinoita Bronnimann, 1952, is as similar as between non-bullate form Globigerapsis and bullate form Globigerinatheka Bronnimann. 1952. The genus Globigerapsis is similar to Globigerinatheka but has no bullae covering the sutural aperture (Bolli, 1972).

Based on the present observation and literature, the forms previously referred to Globigerinoides conglobatus ( Brady) should, in this study, be excluded from Globigerinoides and are now referred to the new genus Alloglobigerinoides.

On the other hand, Globigerinoides gomitulus (Seguenza) may belong to the present genus, and seems closer to the species Alloglobigerinoides conglobatus (Brady).

The type species was cited in the original publication as Alloglobigerinoides conglobatus (Brady). So the genus was explicitly treated as masculine in the original publication.

Opinion of Brummer & Kucera 2022
A monotypic genus erected by Huang (1986) to account for a presumed absence of an umbilical primary aperture on the final chamber in the type species. Whilst there are specimens where the final chamber does obscure the aperture, there are also many specimens where the primary aperture is visible, making the diagnostic character of the genus obsolete in lieu of Globigerinoides.

References:

Brummer, G-J. A. & Kucera, M. (2022). Taxonomic review of living planktonic foraminifera. Journal of Micropalaeontology. 41: 29-74. gs

Huang, T. (1986). Alloglobigerinoides, a new planktic foraminiferal genus. Petroleum Geology of Taiwan. 22: 93-102. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Alloglobigerinoides Huang 1986

Alloglobigerinoides

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