pforams@mikrotax - Tenuitella insolita

Citation: Tenuitella insolita (Jenkins 1966)

Synonyms:

Globorotalia insolita Jenkins, 1966:1120, fig. 13, nos. 113-118 [upper Eocene, Port Elizabeth, New Zealand]. Globorotalia (Turborotalia) insolita Jenkins. Jenkins, 1971:118, pl. 12: figs. 309-314 [upper Eocene, Port Elizabeth, New Zealand].
Praetenuitella insolita (Jenkins). Huber, 1991, pl. 7: figs. 9, 10 [upper Eocene Zone AP12, ODP Hole 738B, Kerguelen Plateau, southern Indian Ocean]. Nocchi, 1991:269, pl. 4: figs. 24-26 [upper Eocene, ODP Hole 703A, South Atlantic Ocean].—Li and Radford, 1992:578, pl. 1: figs. 1-3 [upper Eocene, ODP Hole 749B, Kerguelen Plateau, southern Indian Ocean]. Li and others, 1995:132, pl.3: figs.1-7, 9, 10 [upper Eocene, Brown’s Creek Fm., Otway Basin, southern Australia].
Praetenuitella impariapertura Li, 1987:309, pl. 1: figs. 1-5, text-fig. 6 [upper Eocene, Jackson Group, Clarke County, Mississippi].—Poag and Commeau, 1995:155, pl. 9: figs. 16-17 [Upper Eocene Zone P15, U. S. Geological Survey Exmore Core, Virginia Coastal Plain].
Praetenuitella patefacta Li. Li and others, 1995:127, pl. 4: figs. 1-3 [upper Eocene, ODP Hole 749B, Kerguelen Plateau, southern Indian Ocean]. [Not Li, 1987.]
Not Globorotalia insolita Jenkins.—Jenkins and Orr, 1972, pl. 25, figs. 3-8 [ =Tenuitella? sp.] .

Taxonomic discussion: Li and Radford (1992) and Li and others (1995) distinguished T. impariapertura Li from T. insolita by suggesting the latter species has a more circular test, a more convex dorsal side, and a narrower umbilicus. Given that Jenkins’s (1966) type illustrations shows a triangular to highly arched aperture in his holotype and paratype illustrations, and in light of the morphological variability of specimens illustrated on Plate 16.5, we consider impariapertura to be a junior synonym of insolita. Some of the specimens identified as Praetenuitella patefacta by Li and others (1995, pl. 4, figs. 1-3) exhibit triangular, highly arched apertures that are nearly centered on the equatorial peripheral plane and are therefore here designated as T. insolita.
Poorly preserved upper Eocene specimens identified as Globorotalia insolita by Jenkins and Orr (1972) from DSDP Site 77B (eastern Equatorial Pacific) are considered misidentified as the presence of elongate umbilical flaps, axially compressed tests with a weakly lobate equatorial periphery are not characteristic. We are uncertain of the species identity of their illustrated specimens.
Dissected specimens of T. insolita (e.g., Pl. 16.5, Fig. 10) reveal that a highly arched aperture rimmed by a narrow lip is present in all final whorl chambers in adult specimens. This dissected specimen also shows that the wall microstructure is monolamellar, as observed in the wall of T. praegemma (Pl.16.6, Fig.9) and T. gemma (Pl.16.7, Fig. 15). [Huber et al. 2006]

Distinguishing features:
Parent taxon (Tenuitella): Minute to small, low trochospiral test, with globular chambers. Monolamellar, microperforate wall with a smooth or finely pustulate surface.
This taxon: Distinguished from other tenuitellids by its highly arched and narrow aperture and smooth test surface.

Description

Test small, subquadrate to subcircular and lobate in axial view, equatorial margin rounded; chambers inflated to subglobular, coiled in a moderate trochospire, sometimes becoming nearly planispiral in the final whorl, increasing gradually in size, four to six in the final whorl; sutures depressed, curved on the spiral side, radial on umbilical side; umbilicus small; aperture in early chambers subcircular to circular (Pl. 16.5, Fig. 10), in adult final chambers it is a distinct, high, sometimes triangular arch that may be aligned with the equatorial periphery (e.g., Pl. 16.5, Figs. 5, 12) or offset toward the umbilicus (Pl. 16.5, Figs. 2, 8, 17). [Huber et al. 2006]

Microperforate, monolamellar, surface smooth to finely pustulose, pustules irregularly scattered on umbilical and spiral sides of test. [Huber et al. 2006]

Holotype maximum diameter: 0.16 mm, breadth 0.10 mm. Hypotype maximum diameter 0.19 mm, breadth 0.10 mm. [Huber et al. 2006]

Biogeography and Palaeobiology

Originally described from the Port Elizabeth section (upper Eocene) in New Zealand; also identified in upper Eocene sequences in southern Australia (McGowran, 1987), Japan (Kaiho, 1984), southern South Atlantic Ocean (ODP Site 703; Nocchi and others, 1991) and southern Indian Ocean (ODP Sites 737, 738C, 747 and 749; Huber, 1991; Li and others, 1992). At low latitudes reported from the equatorial Pacific (DSDP Site 77; Jenkins and Orr, 1972) and central Pacific Ocean (DSDP Site 321; Quilty, 1976). [Huber et al. 2006]

An oxygen and carbon isotope cross-plot showing values from T. insolita relative to those from co-occurring benthic and planktonic species is presented in Figure 16.3 for an upper Eocene (~Zone E15-16) sample from Cape May, New Jersey. These data suggest that T. insolita was a relatively deep dwelling planktonic species that either preferred living within the oxygen minimum zone of the water column or had a considerable vital effect causing preferential fractionation of the lighter carbon isotope. The carbon and oxygen isotope values of T. insolita are near those of Dipsidripella danvillensis, suggesting that these species had similar ecological preferences and/or vital effect offset from equilibrium fractionation. [Huber et al. 2006]

The suggestion by Li and others (1995) that T. insolita ( =Praetenuitella impariapertura Li) descended directly from Pseudohastigerina is rejected since the latter species is planispiral and normal perforate whereas T. insolita is trochospiral and microperforate. Li and McGowran (1996) observed that Tenuitella insolita shares a number of morphological features with Cassigerinella eocaenica (C. winniana in their study), including a smooth, microperforate wall structure, minute test size, and high, narrowly arched aperture, but it differs in having a low trochospiral rather than a biserially enrolled coiling mode. The possible relationship between these two species needs further study and other phylogenetic hypotheses for the origin of the tenuitellids need to be explored. Tenuitella praegemma and T. patefacta probably evolved from T. insolita during the latest Eocene. [Huber et al. 2006]

Biostratigraphic distribution

Geological Range:
Notes: Upper Eocene Zone E15; nominate species for the T. insolita Taxon Range Zone (Zone AE9) at southern high latitudes (Huber and Quille_ve_re_, 2005). Originally described from the Port Elizabeth section in New Zealand where it ranges from just above the extinction of Acarinina collactea to just below the extinction of Globigerinatheka spp. (Jenkins, 1971). In the Ocean View Borehole (New Jersey Coastal Plain) the lowest occurrence of T. insolita was recorded within the upper 30 feet of the 200 foot stratigraphic range of Globigerinatheka index (Miller and others, 2003). [Huber et al. 2006]
Last occurrence (top): within E15 zone (34.68-35.89Ma, top in Priabonian stage). Data source: Huber et al. 2006 f16.2
First occurrence (base): within E15 zone (34.68-35.89Ma, base in Priabonian stage). Data source: Huber et al. 2006 f16.2

Primary source for this page: Huber et al. 2006 - Eocene Atlas, chap. 16, p. 489

References:

Huber, B. T., Olsson, R. K. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene microperforate planktonic foraminifera (Jenkinsina, Cassigerinelloita, Chiloguembelina, Streptochilus, Zeauvigerina, Tenuitella, and Cassigerinella) and Problematica (Dipsidripella). 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 16): 461-508. gs O

Jenkins, D. G. & Orr, W. N. (1972). Planktonic foraminiferal biostratigraphy of the east equatorial Pacific--DSDP Leg 9. Initial Reports of the Deep Sea Drilling Project. 9: 1059-1193. gs O

Jenkins, D. G. (1966b). Planktonic foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics. 8 [1965](6): 1088-1126. gs

Jenkins, D. G. (1971). New Zealand Cenozoic Planktonic Foraminifera. New Zealand Geological Survey, Paleontological Bulletin. 42: 1-278. gs

Kaiho, K. (1984). Paleogene foraminifera from Hokkaido, Japan (part 2). Science Reports of the Tohoku University. 55: 1-74. gs

Li, Q. & McGowran, B. (1996). The planktonic foraminifer Cassigerinella winniana (Howe) from southern Australia: Comments on its lineage recognition. Revista Española de Micropaleontología. 28: 97-103. gs

Li, Q. & Radford, S. S. (1992). Morphology and affinity of the planktonic foraminifer Cassigerinelloita amekiensis Stolk and reclassification of Cassigerinelloita Stolk. Proceedings of the Ocean Drilling Program, Scientific Results. 120: 595-602. gs

Li, Q. (1987). Origin, phylogenetic development and systematic taxonomy of the Tenuitella plexus (Globigerinitidae, Globigerininina). Journal of Foraminiferal Research. 17: 298-320. gs

Li, Q., Radford, S. S. & Banner, F. T. (1992). Distribution of microperforate tenuitellid planktonic foraminifers in Holes 747A and 749B, Kerguelen Plateau. Proceedings of the Ocean Drilling Program, Scientific Results. 120: 569-594. gs

Li, Q., McGowran, B. & Boersma, A. (1995). Early Palaeocene Parvularugoglobigerina and late Eocene Praetenuitella: does evolutionary convergence imply similar habitat? Journal of Micropalaeontology. 14: 119-134. gs

McGowran, B. J. (1987). Late Eocene perturbations: foraminiferal biofacies and evolutionary overturn, southern Australia. Paleoceanography. 2: 715-727. gs

Miller, K. G., Sugarman, P. J. & others (2003). Ocean View Site. Proceedings of the Ocean Drilling Program, Initial Reports. 174AX (Suppl.): 1-72 [CD. gs

Nocchi, M., Amici, E. & Premoli Silva, I. (1991). Planktonic foraminiferal biostratigraphy and paleoenvironmental interpretation of Paleogene faunas from the subantarctic transect, Leg 114. Proceedings of the Ocean Drilling Program, Scientific Results. 114: 233-273. gs

Poag, C. W. & Commeau, J. A. (1995). Paleocene to middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: Biostratigraphy, allostratigraphy, and sequence stratigraphy. Journal of Foraminiferal Research. 25: 134-155. gs

Quilty, P. G. (1976). Planktonic foraminifera DSDP Leg 34, Nazca Plate. Initial Reports of the Deep Sea Drilling Project. 34: 629-703. gs O

test outline:	Lobate	chamber arrangement:	Trochospiral	edge view:	Inequally biconvex	aperture:	Extraumbilical
sp chamber shape:	Inflated	coiling axis:	Low	periphery:	N/A	aperture border:	Thin lip
umb chbr shape:	Inflated	umbilicus:	Narrow	periph margin shape:	Broadly rounded	accessory apertures:	None
spiral sutures:	Moderately depressed	umb depth:	Shallow	wall texture:	Smooth	shell porosity:	Microperforate: <1µm
umbilical or test sutures:	Moderately depressed	final-whorl chambers:	4-6	N.B. These characters are used for advanced search. N/A - not applicable