pforams@mikrotax - Hedbergella gorbachikae

Citation: Hedbergella gorbachikae Longoria 1974

Basionym: Hedbergella gorbachikae

Original description: "Plano-convex test; umbilical side convex; last whorl general with 5 inflated chambers, last chamber protruding into the umbilical area covering most of the umbilicus. Test medium sized; plano-convex, spiral side, flatterend, umbilical side convex; periphery subcircular lobate; generally with 5 chambers in the last whorl; ultimate chamber protruding into the umbilical side; early chambers spherical in apertural view, last chamber ovoid; sutures radial, slightly curved, depressed on both umbilical and spiral sides; primary aperture extraumbilical-spiroumbilical; umbilicus completely or partly covered by the last chamber."

Test medium sized, coiled in a flat to very slightly convex trochospire; 2 to 2.5 whorls; 5 to 5.5 (rarely 4.5 chambers in the outer whorl increasing rather gradually and slowly in size as added; chambers globular to subglobular, inflated, the last two or three tending to become subtriangualr on the umbilical side, subtrapezoidal on the spiral side, reniform when viewed laterally; last triangular chamber protruding toward the umbilicus and partly or wholly covering it; equatorial periphery subcircular to slightly ovoid, slightly to moderately lobate; sutures depressed, radial mainly straight; umbilical area small and rather deep; aperture as a low to medium arch bordered by a lip. Wall smooth, finely perforate, that may be covered by perforation cones in the early chambers of the last whorl. [Huber & Leckie, 2011, p. 66]: Emended definition. Test wall finely perforate, smooth with moderately to strongly developed perforation cones on most chambers of the last whorl. Test medium in size, equatorial periphery subcircular to slightly ovoid, slightly to moderately lobate, 2 to 2.5 whorls coiled in a flat to slightly convex trochospire; chambers globular to subglobular, inflated, increase gradually in size, 4.5 to 5.5 in the final whorl with the last two or three tending to become subrounded to subtriangular on the umbilical side, subtrapezoidal on the spiral side, reniform in edge view, last chamber protruding into the umbilicus and partly or completely covering it; sutures depressed, radial and straight; umbilical area small and deep. Aperture a low to medium arch, which may be bordered by an imperforate rim. [copied from Chronos database]

Geological Range:
Last occurrence (top): within P. rohri zone (113.22-116.60Ma, top in Aptian stage). Data source: Huber and Leckie, 2011
First occurrence (base): within H. infracretacea zone (116.60-116.86Ma, base in Aptian stage). Data source: [copied from Chronos database - BUT zonal name changed from gorbachikae to infracretacea - this will be approx correct but may not be precise

References:

Banner, F. T., Copestake, P. & White, M. R. (1993). Barremian-Aptian Praehedbergellidae of the North Sea area: a reconnaisance. Bulletin of the Natural History Museum, London (Geology). 49: 1-30. gs

Huber, B. T. & Leckie, R. M. (2011). Planktic foraminiferal species turnover across deep-sea Aptian/Albian boundary sections. Journal of Foraminiferal Research. 41: 53-95. gs

Leckie, M. (1984). Mid-Cretaceous planktonic foraminiferal biostratigraphy off Central Morocco, Deep Sea Drilling Project Leg 79, Sites 545 and 547. Initial Reports of the Deep Sea Drilling Project. 79: 579-620. gs

Lipson-Benitah, S. & Almogi-Labin, A. (2004). Aptian planktonic foraminifera from Israel. Israel Journal of Earth Sciences. 53(1): 27-46. gs

Longoria, J. F. (1974). Stratigraphic, morphologic and taxonomic studies of Aptian planktonic foraminifera. Revista Española de Micropaleontología. Numero Extraordinario: 5-107. gs

test outline:	Lobate	chamber arrangement:	Trochospiral	edge view:	Planoconvex	aperture:	-
sp chamber shape:	Inflated	coiling axis:	Very low	periphery:	N/A	aperture border:	Thin lip
umb chbr shape:	Inflated	umbilicus:	Narrow	periph margin shape:	Broadly rounded	accessory apertures:	N/A
spiral sutures:	Strongly depressed	umb depth:	Deep	wall texture:	Smooth	shell porosity:	Finely Perforate: 1-2.5µm
umbilical or test sutures:	Strongly depressed	final-whorl chambers:	5-5.5	N.B. These characters are used for advanced search. N/A - not applicable

Hedbergella gorbachikae

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