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Species Hantkenina compressa Parr 1947


Diagnosis / Definition:
Pearson et al. (2006):
DESCRIPTION. Type of wall: Smooth, perforate and probably nonspinose; tubulospines imperforate, smooth or with fine striations. Test morphology: Planispiral, biumbilicate, somewhat conlpressed laterally, although individual chambers are slightly inflated; 5-6 closely appressed chambers in the final whorl, increasing rapidly in size as added, sub-triangular or polygonal in shape; adult chambers extend into a hollow tubulospine; peripheral outline continuous, lobed or slightly angular; aperture is an elongated narrow equatorial arch flaring into lateral lobes, bordered by a wide flaring lip; sutures straight to slightly sigmoidal; tubulospines straight, long and slender or short and triangular, arising sharply from the supporting chamber, positioned at the anterior chamber edge, spanning the suture between adjacent chambers, in contact with the posterior wall of the next youngest chamber along a short portion of the length at the base, inclined forward in the direction of coiling, distal ends taper to points, often with a small coronet structure (Ramsay, 1962), sometimes opening tiom the axial canal into a small terminal aperture. Size: Maximum diameter (excluding tubulospines) 0.40-70 mm.
Discussion / Comments:
Pearson et al. (2006):
DISTlNGUISHING FEATURES.- Hantkenina compressa differs from H. dumblei in the trans-sutural position and more forward-inclined orientation of the tubulospines, often angular periphery and less rapid increase in chamber height in the adult whorl. It is distinguished from H. aalabamensis in lacking the subtangential adult tubulospines and in having more laterally compressed chambers. As in H. alabamensis, the final 2-3 tubulospines of H. compressa are in contact with the posterior wall of the adjacent chambers, but this is not as pronounced as in the former. DISCUSSION.- Hantkenina compressa is intermediate in morphology between H. dumblei and H. alabamensis and overlaps stratigraphically with them both. It thus bridges the supposed evolutionary gap (Blow, 1979) between middle and late Eocene hantkeninids. This morphotype is common in deep sea and land-outcropping pelagic sections but has previously been referred to H. dumblei, H. cf. dumblei or H. alabamensis, which has had the effect of artificially extending the stratigraphic range of H. dumblei into the upper Eocene and lowering the range of H. alabamensis within the middle Eocene. Recognition of H. compressa demands stricter definitions of the latter two species and increases their biostratigraphic utility. The species intergrades with H. alabamensis in the upper Eocene. We have included specimens that are transitional to H. alabamensis to show the range of variability permitted to Hantkenina compressa (Pl. 8.6, Figs. 10, 14,21). The holotype of H. brevispina Cushman, 1924, which is described as having much shorter and stouter tubulospines than other hantkeninids, resembles Parr's (1947) illustrations of H. compressa and may be a prior synonym. The holotype of H. brevispina, however, is missing from the USNM collections and thus unavailable for comparison. We suggest, therefore, that H. brevispina should be suppressed and H. compressa adopted as the valid name for these morphotypes. PHYLOGENETIC RELATIONSHIPS.- Evolved from H. dumblei by a reduction in chamber height and tightening of the planispiral coiling. STRATIGRAPHIC RANGE.- Mid Zone El l to the Eocene/Oligocene boundary. GEOGRAPHIC DISTRIBUTION.- worldwide at low to mid latitudes, also New Zealand. STABLE ISOTOPE PALEOBIOL0GY.- Hantkenina compressa from Zone E12 registers relatively low ň18O and high ň13C, similar to coexisting Morozovelloides and Acarinina (Coxall and others, 2000), indicating that it lived in warm waters of the surface mixed layer. There is no 613C -enrichment trend with increasing test size.
Systematics:

35
 Ordo Foraminiferida
  Superfamilia Globigerinaceae
   Familia Hantkeninidae
    Genus Hantkenina
     Species Hantkenina compressa
      Species Hantkenina dumblei
Synonym list:
Pearson et al. (2006):
? 1924 Hantkenina brevispina Cushman. - Cushman : p.2 pl. 2; fig. 3 [upper Eocene, Rio Pantepec, Buena Vista, Mexico]; [Probable synonym. Holotype lost.]
1939 Hantkenina alabamensis Cushman. - Rey : p.325 pl. XXII; fig. 13 [upper Eocene and lower Oligocene, Nummulitique du Rharb, Morocco]; [Not Cushman, 1924]
1947 Hantkenina compressa Parr. - Parr : p.46 text-fig. 1-7; fig. 7-7a [probably upper Eocene, (Bartonian), Brown's Creek coastal section, Victoria, Australia]
1950 Hantkenina (Hantkenina) alabamensis Cushman. - Brönnimann : p.414 pl. 56; fig. 14-15 [upper Eocene, Oceanic Fm. Barbados]
1968 Hantkenina alabamensis Cushman. - Raju : p.291 pl. 1; fig. 11 [upper Eocene Turborotalia cerroazulensis Zone, Cauvery Basin, India]
1979 Hantkenina (Hantkenina) alabamensis Cushman. - Blow : p.1157 pl. 13; fig. 3, 6 [Zone P13, middle Eocene, Kilwa area, Tanzania]; [Not Cushman, 1924]
1979 Hantkenina (Hantkenina) primitiva Cushman. - Blow : p.1161 pl. 234; fig. 4 [upper Eocene, Zone PI 6, Lindi, Tanzania]; [Not Cushman and Jarvis, 1929]
1988 Hantkenina cf. dumblei Weinzierl & Applin. - Coccioni : p.85 pl. 1; fig. 10-11 [upper Eocene, Zone P1 6, Massignano, Italy]; [Not Weinzierl and Applin, 1929]
2006 Hantkenina compressa Parr. - Pearson et al. : p.235 pl. 8.6; fig. 1-21 (Pl. 8.6: Figs. 1-4: original illustrations of the holotype and paratype of Hantkenina compressa Parr)
References:

Cushman,J.A. (1924):
A new genus of Eocene foraminifera . Proceedings of the U.S. National Museum Vol. 66 p. 1-4

Rey,M. (1939):
Distribution stratigraphique des Hantkenina dans le Nummulitique du Rharb (Maroc) . Bulletin de la Société Géologique de France Vol. 5 p. 321-341

Parr,W.J. (1947):
An Australian record of the foraminiferal genus Hantkenina . Proceedings of the Royal Society of Victoria, Melbourne Vol. 58 p. 45-47

Brönnimann,P. (1950):
The Genus Hantkenina Cushman in Trinidad and Barbados, B.W.I. . Journal of Paleontology Vol. 24 p. 397-420

Raju,D.S.N. (1968):
Eocene-Oligocene planktonic foraminiferal biostratigraphy of Cauvery basin, South India . Memoires of the Geological Society of India Vol. 2 p. 286-289

Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp

Coccioni,R. (1988):
The genera Hantkenina and Cribrohantkenina (Foraminifera) in the Massignano section (Ancona, Italy).
In: The Eocene-Oligocene Boundary in the Marche-Umbria Basin (Italy), Ancona International Subcommission on Paleogene Stratigraphy, Special Publication II Vol. 2 Eds: Premoli Silva, I.Coccioni, R.Montanari, A.. p. 81-96

Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
Anonymous: Unedited TaxonConcept data
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