Citation: Globoquadrina subdehiscens Finlay 1947Rank: speciesType specimens: Not given.[It was to be illustrated in Part 6 of Finlay's "New Zealand foraminifera," but this was never published.]: Cotypes to be deposited in the Cushman Laboratory for Foraminiferal Research, Sharon, Mass., and in the Parr Collection, Melbourne, Australia. Type age (chronostrat): Lower Miocene, Altonian Range: Middle Oligocene to Upper MioceneType locality: Sample number 5730, Pakaurangi Point, New Zealand. Other locality given: No.3073, MoutaraPoint,Poverty Bay, Hawke's Bay Province, North Island, New Zealand (Upper Miocene, Kapitean).Type repository: Lower Hutt; New Zealand Geological Survey
Original Description "Close to the Australian dehiscens, but more tightly wound. In both top and bottom views of dehiscens 4 chambers can be about equally seen, due to tendency of the last to swing outwards and so not obscure the chamber it runs on to; in subdehiscens chambers are joined somewhat askew, each succeeding one with a twist downwards and backwards, this constant realignment resulting in a tighter coil with last chamber tending to swing inwards and obscure the one it runs on to thus in ventral view only 3 large chambers are prominent, the fourth half hidden, and in senile specimens totally covered, by a small smooth accessory chamber filling the gap between last and third last. This results in a squarer outline for the New Zealand species, though individual chambers are more inflated than in dehiscens, leading to much deeper sutures both ventrally and dorsally; occasional specimens of subdehiscens have the chambers so inflated as to be subglobular, but the squarish general outline is maintained, Because of greater projectiom ana twist of chambers umbilicus is deeper and more enclosed, sometimes so much so that only a small opening remains and little sign of apertures and flaps can be seen. As in dehiscens, surface is covered with dense punctae and fine papillae all over; on early chambers and especially on points of projections surrounding umbilicus papillae are much stronger, while on final chambers they tend to become obsolete, leaving only the dense punctae.
Size: Size. 0.7 mm. Extra details from original publication "This is an important species in New Zealand at the beginning and end of its range. Its sudden entry in the Waitakian [Middle Oligocene] makes it one of the most useful index species for separating marly deposits from those of Duntroonian [Lower Oligocene] age. No apparent difference can be seen in the abundant specimens that occur from then on to the Tongaporutuan (Mid-Oligocene to Upper Miocene), No occurences are known in typical Kapitean [uppermost Miocene] , but there are specimens in sample no. 3073 (Moutara Point, Poverty Bay) which has a fauna believed to be a facies of Kapitean; this is the last appearance." Editors' Notes Not illustrated. Considered to be synonym of G. dehiscens by Jenkins (1960) and Hornibrook (1958).
Finlay, H. J. (1947). New Zealand foraminifera: Key species in stratigraphy - no. 5. New Zealand Journal of Science and Technology. 28(5): 259-292. gs
Hornibrook, N. d. B. (1958). New Zealand Upper Cretaceous and Tertiary foraminiferal zones and some overseas correlations. Micropaleontology. 4: 25-38. gs
Jenkins, D. G. (1960). Planktonic foraminifera from the Lakes Entrance oil shaft, Victoria, Australia. Micropaleontology. 6: 345-371. gs
Globoquadrina subdehiscens compiled by the pforams@mikrotax project teamviewed: 1-6-2023