Jenkins (1965) produced the first detailed description of H. australis and selected a type specimen out of the six incomplete specimens from Finlay’s original sample that satisfactorily represents the taxon. This specimen is illustrated in SEM for the first time (Pl.8.5, Figs. 1-2). Bronnimann (1950) and Ramsay (1962) recorded H. australis in Trinidad and Tanzania respectively but in both cases the identification was
based on Finlay’s paratype and the illustrated specimens do not have recurved tubulospines.
Our concept of H. australis is based on Finlay’s (1939) and Jenkins’s (1965) notion of a form with backward curving tubulospines. Subbotina’s (1953) illustrations of ‘Hantkenina alabamensis’ clearly show this distinctive feature. We have found this species in correlatable sequences from the southern Labrador Sea (ODP Site 647), Uzbekistan, southern Russia and the Ukraine (Beniamovski, pers. comm., 2001), indicating that it has a global distribution. It appears to be most common at the high southerly and northerly extremes of the hantkeninid latitudinal range suggesting it was more tolerant of cold water than other hantkeninids. In parallel with the H. dumblei-H. compressa -H. alabamensis transition, there is a tendency for the test to become more inflated through time. Hantkenina compressa coexists with H. australis in the upper middle Eocene in New Zealand. A common feature of this taxon is for tubulospines to be absent on the early chambers as in H. primitiva, which makes it impossible to distinguish between them when the tubulospines are missing. [Coxall & Pearson 2006]
Distinguishing features: Species showing features of H. dumblei and H. compressa, but unique in having posteriorly recurved tubulospines.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.
Diagnostic characters: This species has a variable test morphology, showing features of H. dumblei and H. compressa. It differs from both, and all other species of Hantkenina in having posteriorly recurved tubulospines. [Coxall & Pearson 2006]
Wall type: Smooth, normal perforate, probably nonspinose; average pore size is often smaller than in other species of Hantkenina; tubulospines imperforate, smooth or with spiral rifling. [Coxall & Pearson 2006]
Test morphology: Planispiral, laterally compressed with 5-6 closely appressed subtriangular chambers in the final whorl; peripheral outline lobed or slightly angular, anterior chamber shoulder is minimal or non-existent; most or all of the adult chambers extend into a hollow tubulospine; primary aperture is an equatorial high arch extending about halfway up the apertural face, widening towards the base into weak basal lobes and bordered on each side by an imperforate lip; sutures depressed, straight or slightly sigmoidal; pustules common on early chambers of the final whorl and in the umbilical region; tubulospines slender, often long, curved backwards slightly in the opposite direction to coiling, tapering to a point, arising sharply from the supporting chamber, positioned at or just spanning the anterior chamber suture, sometimes partially contacting the adjacent younger chamber. [Coxall & Pearson 2006]
Size: Maximum diameter without spines: 0.45 mm, with spines, 0.56 mm (Jenkins, 1965). [Coxall & Pearson 2006]
|test outline:||Lobate||chamber arrangement:||Planispiral||edge view:||Compressed||aperture:||Equatorial|
|umb chamber shape:||Subtriangular||coiling axis:||N/A||periphery:||Tubulospines||aperture border:||Thin lip|
|sp chbr shape:||Subtriangular||umbilicus:||Wide||periph margin shape:||Subangular||accessory apertures:||Sutural|
|umbilical or test sutures:||Moderately depressed||umb depth:||Shallow||wall texture:||Smooth||shell porosity:||Finely Perforate: 1-2.5µm|
|spiral sutures:||Moderately depressed||final-whorl chambers:||5.0-6.0|
Geographic distribution: Global, low to mid latitudes, most common at the high northerly and southerly extremes of the hantkeninid range, i.e., New Zealand, southern Labrador Sea. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Low to middle latitudes and commonly in high northerly and southerly extremes; based on Coxall & Pearson (2006)
Isotope paleobiology: No data available. [Coxall & Pearson 2006]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study
Phylogenetic relations: Probably evolved from H. dumblei in the middle Eocene. [Coxall & Pearson 2006]
Most likely ancestor: Hantkenina dumblei - at confidence level 4 (out of 5). Data source: Coxall & Pearson (2006) fig 8.1.
Notes: Middle Eocene, Zones E11-E13. [Coxall & Pearson 2006]
Last occurrence (top): near top of E13 zone (90% up, 38.2Ma, in Bartonian stage). Data source: Coxall & Pearson (2006) fig 8.1
First occurrence (base): at top of E11 zone (100% up, 40.4Ma, in Lutetian stage). Data source: Coxall & Pearson (2006), fig. 8.1
Plot of occurrence data:
Primary source for this page: Coxall & Pearson 2006 - Eocene Atlas, chap. 8, p. 232
Brönnimann, P., (1950). The Genus Hantkenina Cushman in Trinidad and Barbados, B. W. I. Journal of Paleontology, 24(4): 397-420. Coxall, H.K. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of the Hantkeninidae (Clavigerinella, Hantkenina and Cribrohantkenina). In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 213-256. Cushman, J.A., (1924). A new genus of Eocene foraminifera. Proceedings of the United States National Museum, 66(2567): 1-4. Finlay, H.J., (1939). New Zealand Foraminifera: The Occurrence of Rzehakina, Hantkenina, Rotaliatina, and Zeauvigerina. Transactions of the Royal Society of New Zealand, 68(4): 534-543. Jenkins, D.G., (1965). Planktonic Foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics, 8(6): 1088-1126. Ramsay, W.R., (1962). Hantkeninidae in the Tertiary rocks of Tanganyika. Contributions from the Cushman Foundation for Foraminiferal Research, 13: 78-89. Thalmann, H.E., (1942). Foraminiferal genus Hantkenina and its subgenera. American Journal of Science, 240: 809-820.
Brönnimann, P., (1950). The Genus Hantkenina Cushman in Trinidad and Barbados, B. W. I. Journal of Paleontology, 24(4): 397-420.
Cushman, J.A., (1924). A new genus of Eocene foraminifera. Proceedings of the United States National Museum, 66(2567): 1-4.
Finlay, H.J., (1939). New Zealand Foraminifera: The Occurrence of Rzehakina, Hantkenina, Rotaliatina, and Zeauvigerina. Transactions of the Royal Society of New Zealand, 68(4): 534-543.
Jenkins, D.G., (1965). Planktonic Foraminiferal zones and new taxa from the Danian to lower Miocene of New Zealand. New Zealand Journal of Geology and Geophysics, 8(6): 1088-1126.
Ramsay, W.R., (1962). Hantkeninidae in the Tertiary rocks of Tanganyika. Contributions from the Cushman Foundation for Foraminiferal Research, 13: 78-89.
Hantkenina australis compiled by the pforams@mikrotax project team viewed: 18-10-2018