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Pseudothalmanninella ticinensis


Classification: pf_mesozoic -> Rotaliporidae -> Pseudothalmanninella -> Pseudothalmanninella ticinensis
Sister taxa: P. klausi, P. subticinensis, P. tehamaensis, P. ticinensis, P. sp.

Taxonomy

Citation: Pseudothalmanninella ticinensis (Gandolfi, 1942)
Rank: Species
Basionym: Globotruncana ticinensis
Taxonomic discussion: Very abundant in some samples, in the Breggia section it is confined to the lower part of the Scaglia Bianca. Strongly variable in what concerns the formation of the keel in single chambers and chamber convexity. Such a modifications occur in a thin stratigraphic interval, at the beginning (level 28), specimens with chambers only slightly pinched at the margin, and in part overlapping and bounded by rare pustules in the inner whorls; then (level 29), specimens with angular chambers clearly keeled. In between these two end members there is a full set of intergradations, that through a beaded keel lead to the formation of a neat, smooth keel. Accordingly, it was possible to separate
a) [copied from Chronos database] specimens generally with a beaded keel, rarely smooth and well distinct, confined to the inner chambers or only apparent in the outer ones, Globotruncana ticinensis var. alpha n. var.;
b) [copied from Chronos database] specimens with chambers clearly keeled also in the outer whorl, typical form.
The variety alpha displays some relationship with Anomalina roberti; the typical form is also related to Globotrucana appenninica s. str. through a set of transitions.
The fundamental differences between the species ticinensis and appenninica are as follows;
Globotruncana ticinensis: more numerous chambers in the last whorl (8-9), outline more uniform and regular, chambers more separated, sutures more radial and straight, slower increase in size of chambers.
Globotruncana appenninica: lower number of chambers in the last whorl (6), more lobate outline, chambers more overlapping, sutures more curved, faster increase in size of chambers.
Regarding the set of intermediates forms between the two mentioned species, we like to mention that at level 33 there are specimens, with the last chambers larger the in typical G. ticinensis, and in level 34 there are already typical specimens of G. appenninica.
In thin transverse sections the variety alpha exhibits well pinched inner chambers, whereas the outer ones are less compressed and occasionally well round. Moreover, pores are less concentrated where the chamber displays only a slight compression, whereas pores are absent where the keel is formed.
Such a tranverse sections are difficult to separate from those of the intermediates between G. appenninica and G. cretacea except for the much larger sizes of T. ticinensis, and the concomitant presence of equatorial sections which show a much greater number of chambers (around 8 to 9), in the last whorl. Transverse sections of typical ticinensis in general cannot be distinguihed from appenninica analogues; again the presence of equatorial sections is decisive (8-9 chambers vs 6 in appenninica). The slight overlap of chambers and less rough wall texture allow to distinguish them from the sections of T. roberti.
Concerning the shape, the species ticinensis is easily distinguihed from all the other known species for the elevated number of chambers and coiling. The only one with which it can be compared is Globotruncana conica White, which however displays a much more planoconvex profile and marked beaded keeled sutures on the umbilical side. [copied from Chronos database]

Type images:

Original description: Translation from Italian: Shell, circular in outline, convex on the spiral side, plane or slightly concave on the umbilical side, peripheral margin subangular; spire trochoidal consisting of 2-3 whorls of chambers, initially globigeriniform, then compressed, arcuate, slightly overlapping and slowly increasing in size. The sutures, initially depressed and indistinct, become bordered by a thin marginal keel, slightly larger and evident in between coils and chambers.

On the umbilical side chambers are more convex, sutures radial, slightly curved and deep, umbilicus of medium size, around which some thickening is generally present. The last chamber is somewhat more subangular delimiting a terminal face, the inner corner of which is prolonged sometimes large and round in some kind of an appendix into the umbilicus. Wall texture porous, apparently coarser than in Globotruncana appenninica s. str., less than in the genus Anomalina and Globigerina. Coiling indifferently sinistral and dextral.

Conchiglia dal contorno rotondo, convessa superiormente, piana o poco concava inferiormente, bordo depresso; spirale trocoide, composta di 2-3 giri di camere; globigerinoidi in principio, depresse poi, arcuate, ricoprentesi poco e poco crescenti. Le suture, dapprima depresse e indistinte, divengono orlate da un listello marginale, fine, un po' più largo ed evidente tra una spira e l'altrà che tra camera e camera. Le ultime due o tre camree talvolta a bordo un po' depresso, listello carenale appena segnato; l'ultima camera anche solo convessa e affusolata senza carena.

Nella parte ombelicale le camere sono più convesse che superiormente, le suture radiali, poco curve, profonde, ombelico di media grandezza, intorno al quale appare di solito una specie di callosità. L'ultima camera è un po' angolosa così che si viene a delimitare una faccia terminale, il cui spigolo interno si prolunga talvolta largo e arrotondato in una specie di appendice nell'ombelico stesso. Tessitura porosa, apparentemente più grossolana che nella Globotruncana apenninicca s. str. meno che nel genere Anomalina e Globigerina. L'avvolgimento è indifferentemente sinistro e destro giro.

Entries in the Catalog of original descriptions: Globotruncana ticinensis

Geological Range:
Last occurrence (top): within P. appenninica zone (100.50-101.92Ma, top in Albian stage). Data source: [copied from Chronos database]
First occurrence (base): at base of P. ticinensis zone (0% up, 103.9Ma, in Albian stage). Data source: zonal marker (from Timescale Creator)

Plot of range and occurrence data:

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Petaloidcoiling axis:Moderateperiphery:Single keelaperture border:Thin lip
umb chbr shape:Trapezoidalumbilicus:Narrowperiph margin shape:Subangularaccessory apertures:Umbilical
spiral sutures:Raised beadedumb depth:Deepwall texture:Finely pustuloseshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:8.0-9.0 N.B. These characters are used for advanced search. N/A - not applicable

References:

Gandolfi, R. (1942). Ricerche micropaleontologiche e stratigraphfiche sulla Scaglia e sul flysch Cretacici dei Dintorni di Balerna (Canton Ticino). Rivista Italiana di Paleontologia. 48: 1-160. 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 V O

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

Petrizzo, M. R. & Huber, B. T. (2006). Biostratigraphy and taxonomy of late Albian planktonic foraminifera from ODP Leg 171B (western North Atlantic Ocean). Journal of Foraminiferal Research. 36: 166-190. gs

Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs

Reichel, M. (1949b). Observations sur les Globotruncana du gisement de la Breggia (Tessin). Compte Rendu de la Societe Paleontologique Suisse. 42(2): 596-617. gs


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Pseudothalmanninella ticinensis compiled by the pforams@mikrotax project team viewed: 23-11-2020

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