Original description: Praehedbergella ruka n.sp. sensu. lato.
DIAGNOSIS. Characterized by its high trochospire, strong dorsal covexity (and 4 to 4½ chambers in the last whorl).
DESCRIPTION. Test about 0.15 mm at its maximum diameter ' comprising about three whorls coiled in a high trochospire. There are 5 chambers in the penultimate whorl but 4-4½ in the final whorl. The spiral side is strongly convex and the intercameral sutures are moderately depressed forming inter- cameral angles of about 135°-140° at the periphery of the test. The chambers are symmetrical and increase in size gradually with growth. The chambers in the last whorl are either slightly depressed (about 2/3 as high as long when viewed from the spiral side), or depressed (about half as high as long when viewed dorsally). The final chamber may be about as high as long. The umbilicus is small and the aperture is a narrow slit.
Entries in the Catalog of original descriptions: Praehedbergella ruka, Praehedbergella ruka ruka, Praehedbergella ruka contritus, Praehedbergella ruka papillata
Emended description: Test small to medium, coiled on a high trochospire; 2 to 2.5 whorls; 4 to 4.5 chambers in the outer whorl increasing slowly to rather rapidly in size as added; chambers globular to subglobular, inflated, the last one tending to be slightly reniform in edge view; equatorial periphery rather compact to cross-shaped, slightly to moderately lobate; sutures depressed, radial mainly straight; umbilical area small and rather deep to absent; aperture as a low to medium arch bordered by a lip. Wall smooth, finely perforate, that may be covered by perforatipon cones in the early chambers of the last whorl. [Huber & Leckie, 2011, p. 72]: Emended description. Test wall smooth, finely perforate, pores evenly distributed, surface with small perforation cones on all but the final adult chamber. Test small to medium, coiled in a moderately high trochospire with 2-2.5 whorls; chambers increasing moderately in size as added with about 5 in the early whorl and 4 in the final whorl, chambers globular, inflated; equatorial periphery rounded, lobate; sutures depressed, radial and straight; umbilical area narrow and deep; aperture a low-umbilical to extraumbilical arch with thin imperforate rim, but without a bordering lip or other eriapertural structures. [copied from Chronos database]
Last occurrence (top): within T. bejaouaensis zone (113.26-118.02Ma, top in Aptian stage). Data source: [copied from Chronos database]
First occurrence (base): within G. blowi zone (125.71-128.73Ma, base in Barremian stage). Data source: [copied from Chronos database]
Plot of occurrence data:
Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous
|test outline:||Lobate||chamber arrangement:||Trochospiral||edge view:||Spiroconvex||aperture:|
|sp chamber shape:||Globular||coiling axis:||High||periphery:||N/A||aperture border:||Thin lip|
|umb chbr shape:||Globular||umbilicus:||Narrow||periph margin shape:||Broadly rounded||accessory apertures:||N/A|
|spiral sutures:||Moderately depressed||umb depth:||Deep||wall texture:||Smooth||shell porosity:||Finely Perforate: 1-2.5µm|
|umbilical or test sutures:||Moderately depressed||final-whorl chambers:||4.0-4.5||N.B. These characters are used for advanced search. N/A - not applicable|
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
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
Hedbergella ruka compiled by the pforams@mikrotax project team viewed: 15-12-2019
Short stable page link: http://mikrotax.org/pforams/index.php?id=110261 Go to Archive.is to create a permanent copy of this page - citation notes