Like P. nana but larger, and with a more rapid rate of chamber expansion, a less compact test, a higher arched aperture, elongation of the chambers in the direction of coiling, and slightly curved spiral sutures.
Like P. pseudokugleri but the final chamber shows a distinct pinching; the chambers are less inflated and more appressed; the outline is more ovate and less lobulate; spiral side sutures are more strongly curved and less depressed.
Like P. siakensis but with slightly curved spiral sutures and generally higher arched aperture, and less strongly developed lip.
Paragloborotalia siakensis Like P. nana but with more chambers (5-7) in the final whorl, less embracing chambers, more rapid rate of chamber expansion, and a higher arched aperture.
Paragloborotalia nana Test small, compact, quadrangular, usually 4 chambers in the final whorl. Umbilicus very narrow, sutures radial. Aperture with prominent lip, which often obscures the primary aperture.
Paragloborotalia griffinoides Small, very low trochospiral, compact, subquadrate test. Aperture with a thickened continuous lip. Wall coarsely cancellate.
Citation: Paragloborotalia Cifelli, 1982Rank: GenusType species: Globorotalia opima subsp. opima Bolli, 1957.Synonyms: Jenkinsella Kennett and Srinivasan, 1983:171.Taxonomic discussion: “The type species of Paragloborotalia, P. opima (Bolli), is an Oligocene taxon of great biostratigraphic utility that was originally described as belonging to the nonspinose genus Globorotalia. However, in an early application of wall texture based taxonomy, Cifelli (1982) showed that opima possesses a cancellate wall and, on account of observed spine holes, must originally have been spinose” (Olsson and others, 2006:91). [Leckie et al. 2018]
Paragloborotalia experienced considerable evolutionary changes through the Oligocene – middle Miocene, particularly a period of accelerated evolutionary turnover (speciation and extinction) across the Oligocene/Miocene boundary and in the earliest Miocene (Figure 5.1). Major evolutionary trends include: 1) originally 4-5 chambers in the final whorl (ancestral condition), to 6 chambers in the mid- to late Oligocene, and finally up to 7 chambers in the early and middle Miocene; 2) radial spiral sutures through the mid Oligocene (Zone O5; ancestral condition), appearance of slightly curved spiral sutures in the late Oligocene (Zones O6-O7), to more strongly curved spiral sutures in some taxa in the early Miocene (Zone M1) – a trend also noted by Keller (1981); and 3) broadly rounded peripheral margin through the mid-Oligocene (Zone O5; ancestral condition) to some taxa with subacute margins in the late Oligocene and early Miocene. Species of Paragloborotalia range in size from small (0.35 mm) (e.g., Spezzaferri, 1994; Wade and others, 2007, 2016). [Leckie et al. 2018]
Kennett and Srinivasan (1983) erected Jenkinsella (type species siakensis) as a subgenus of Globorotalia, for low trochospiral forms with globular to subglobular chambers, a rounded peripheral margin, lacking a distinct carina, with an umbilical-extraumbilical aperture bordered by a rim. Jenkinsella included opima, semivera, siakensis, bella, mayeri and acrostoma. Paragloborotalia was erected by Cifelli in 1982 and therefore has seniority over Jenkinsella, which is here considered a junior synonym. [Leckie et al. 2018]
Paragloborotalia is distinguished from Parasubbotina by a slower rate of chamber growth and inflation, more embracing chambers, and generally more heavily encrusted test. [Leckie et al. 2018]
Distinguishing features: Very low trochospiral test with low-arched umbilical-extraumbilical aperture with a thick lip; 4-5 chambers in the ultimate whorl, and a coarsely cancellate, sacculifer-type wall.
NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They are being edited as the site is developed and comments on them are especially welcome.
Description
Wall type: Normal perforate, coarsely cancellate, sacculifer-type wall texture (Olsson and others, 2006); spinose in life (Cifelli, 1982), although all evidence to date suggests that the wall was sparsely or weakly spinose. [Leckie et al. 2018] Morphology: “Very low trochospiral, globular, compact, subquadrate to quadrate in outline, chambers globular, much embracing; in spiral view, 4 to 5 globular chambers, increasing rapidly, then moderately in size, strongly embracing chambers in ultimate whorl, ultimate chamber may be reduced in size, flattened or slightly concave, sutures slightly depressed, straight; in umbilical view 4 to 5 globular, embracing chambers that often close off umbilicus, sutures slightly depressed, straight; in edge view periphery rounded, aperture, umbilical-extraumbilical, a low arch, bordered by a narrow, thickened lip” (Olsson and others, 2006:88). Paragloborotalia species have a strong tendency to develop a calcite crust (Pearson and Wade, 2009; Chapter 3, this volume). [Leckie et al. 2018]
Biogeography and Palaeobiology
Geographic distribution: Cosmopolitan, although most species are more typical of low to mid-latitudes (Jenkins, 1971; Kennett and Srinivasan, 1983; Leckie and others, 1993; Spezzaferri, 1994). [Leckie et al. 2018] Phylogenetic relations: Paragloborotalia evolved from Parasubbotina in the early Eocene (Olsson and others, 2006). Multiple species and several lineages evolved from Paragloborotalia nana (Figure 5.1). The genus Paragloborotalia gave rise to the smooth, nonspinose genus Globoconella in the early Miocene, and the keeled genus Fohsella later in the early Miocene. Paragloborotalia may also be the direct ancestor of the nonspinose Neogloboquadrina in the late Miocene. [Leckie et al. 2018]
Geological Range: Notes: Lower Eocene Zone E7 (Olsson and others, 2006) to Miocene Zone M13. The youngest recorded species attributed to Paragloborotalia is P. continuosa. Last occurrence (top): in upper part of Messinian Stage (58% up, 6.1Ma, in Messinian stage). Data source: Total of range of species in this database First occurrence (base): at base of Ypresian Stage (0% up, 56Ma, in Thanetian stage). Data source: Total of range of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Globigerinidae
Primary source for this page: Leckie et al. 2018 - Olig Atlas chap.5 p.127 (major revision of Olsson et al. 2006 - Eocene Atlas, chap 5, p. 88)
References:
Blow, W. H. (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden. 2: 1-1413. gs
Bolli, H. M. (1957b). Planktonic foraminifera from the Oligocene-Miocene Cipero and Lengua formations of Trinidad, B.W.I. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli & E. Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 97-123. gsVO
Cifelli, R. (1982). Early Occurrences and some Phylogenetic Implications of Spiny, Honeycomb Textured Planktonic Foraminifera. Journal of Foraminiferal Research. 12(2): 105-115. gs
Leckie, R. M. et al. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene and Lower Miocene Paragloborotalia and Parasubbotina. In, Wade, B. S., Olsson, R. K., Pearson, P. N., Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 46(Chap 5): 125-178. gsVO
Olsson, R. K., Pearson, P. N. & Huber, B. T. (2006c). Taxonomy, biostratigraphy, and phylogeny of Eocene Catapsydrax, Globorotaloides, Guembelitrioides, Paragloborotalia, Parasubbotina, and Pseudoglobigerinella n. gen. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 41(Chap 5): 67-110. gsVO
Paragloborotalia compiled by the pforams@mikrotax project teamviewed: 4-8-2021
/Globorotalia (Turborotalia) pseudokugleri/Blow 1969 pl10 f04-6.JPG)
