Hantkenina mexicana Cushman 1924 from: Pearson, P.N.Olsson, R.K.Hemleben, C.Huber, B.T.Berggren, W.A. (2006): Atlas of Eocene Planktonic Foraminifera. p. 1-513 | . |
Notice: This catalogue page may contain unedited data.
|
Species Hantkenina mexicana Cushman 1924 |
|
|
|
| Alternative name: |
|
| Diagnosis / Definition: |
Pearson et al. (2006):
DESCRIPTION.
Type of' wall: Smooth, normal perforate and
probably nonspinose; tubulospines imperforate or with
small, scattered pores, smooth or finely striated with a
well-defined zone of demarcation between the
tubulospines and the chamber wall.
Test morphology: Planispiral, evolute,
biumbilicate or showing a slightly raised spiral side and
very shallow umbilicus; laterally compressed with 4-5
rapidly expanding chambers in the final whorl; final
whorl chambers radially elongate or digitate, wellseparated,
inflated peripherally and more compressed
within the umbilical region; some specimens, including
the holotype, exhibit anterior flexure of the final
chamber; peripheral outline distinctly stellate; each
chamber of the adult whorl extends gradually into a
hollow tubulospine; aperture is a narrow, elongate
equatorial arch bordered by an imperforate flaring lip,
often with a crenulated andtor pustulose margin, relict
apertural lips are sometimes preserved as 'webs' along
the sutures; sutures straight, becoming curved in the final
stages, only partially contacting adjacent chamber;
tubulospines variable in form, broad-based and stout or
long and slender, positioned centrally with respect to
the radial chamber axis, directed radially between
anterior and posterior chamber shoulders, distal ends
usually blunt and closed (although it is possible that a
terminal aperture existed in life) and commonly possess
terminal finger-like projections (coronet structure of
Ramsay, 1962).
Size: Maximum diameter (excluding
tubulospines) 0.50 mm, with spines 0.75 mm or more
(Cushman, 1924). |
| Discussion / Comments: |
Pearson et al. (2006):
DISTINGUISHING FEATURES.-
Hantkenina
mexicana is distinguished from H. liebusi by the more
central position of the tubulospines on each chambers.
The peripheral outline of H. mexicana is also more distinctly stellate. It differs from H. lehneri (sensu
stricto), which also has elongate 'finger-like' chambers,
by having a more deeply incised peripheral outline and
fewer chambers in the final whorl.
DISCUSSION.-
We regard H. mexicana as a senior
synonym of H. nuttalli Toumarkine, 198 1. Various
authors have used Toumarkine's (1981) concept of H.
nuttalli to represent 'primitive-looking' early
hantkeninids with digitate chambers and stout, broad
based tubulospines. Although there may be a case for
distinguishing these forms we have been unable to
consistently recognize these morphologic differences in
populations of early hantkeninids. Moreover, the
holotype of H. nuttalli (one of three H. avagonensis
syntypes selected by Nuttall, 1930) does not clearly
demonstrate the features claimed by Toumarkine's
(198 l) description (i.e. large, in4lated chambers, which
taper more gradually into the terminal spines) because
all the tubulospines have broken off. Therefore,
following Blow (1979) we adopt a broad sense of H.
mexicana to include the spectrum of early stellate hantkeninid morphologies from their origin at the base
of the middle Eocene. However, we do recognize a new
species transitional from Clavigerinella to Hantkenina,
namely H. singanoae n. sp. (see below).
PHYLOGENETIC RELATIONSHIPS.-
Hantkenina
mexicana evolved from H. singanoae by lengthening
of the terminal protrusion into a straight, imperforate
hollow tubulospine. It gave rise to H. liehusi by
reduction in chamber height and a shift in the position
of the tubulospines towards the anterior suture.
STRATIGRAPHIC RANGE.-
Lower middle Eocene. Base of Zone E8 to E9.
GEOGRAPHIC DISTRIBUTION.-
Worldwide,
restricted to low latitudes. Usually rare i i ~op en ocean
sections and, thus, has been an unreliable marker for
the base of planktonic foraminiferal Zone P1 0 (Berggren
and others, 1995). Common in ODP Site 865, Mexico,
US Gulf Coast and coastal Tanzania sections.
STABLE ISOTOPE PALEOBI0LOGY.-
Hantkenina
mexicana has higher òl8O and lower ò13C than all other
co-occurring planktonic species, including the
subbotinids, indicating a cold, deep, possibly subthermocline
habitat (Coxall and others, 2000; Pearson
and others, 2001). A sample analyzed by Boersma and
others (1987) as H. aragonevisis had isotopic ratios
similar to co-occurring subbotinids.
REPOSITORY.-
The holotype of H. mexicana is
missing from the USNM collection. Attempts to resample
the type section and find a new type specimen
in the type material have been unsuccessful. Since the
type illustration is satisfactorily detailed and the species
concept is well established it seems unnecessary to find
a neotype. |
| Systematics: |
35
Ordo Foraminiferida
Superfamilia Globigerinaceae
Familia Hantkeninidae
Genus Hantkenina
Species Hantkenina mexicana
|
| Synonym list: |
Pearson et al. (2006):
1924 Hantkenina mexicana Cushman. - Cushman : p.3 pl. 2; fig. 2 [Eocene,
La Laja, Tierra Colorado, Mexico]
1930 Hantkenina mexicana var. aragonensis Nuttall. - Nuttall : p.284 pl. 24; fig. 2-3 (fig. 3 = holotype H. nuttalli Toumarkine by
subsequent designation); [upper Lower Eocene, Aragon
Fm., La Antigua, Mexico]
1950 Hantkenina (Avagonella) mexicana Cushman. - Brönnimann : p.405 pl. 55; fig. 1-6 [lower and middle Eocene,
figs. 1-2, 5, 6, Friendship Quarry, Trinidad; figs. 3-4,
Sangrande area, Trinidad]
1962 Hantkenina (Aragonella) lehneri Cushman & Jarvis. - Ramsay : p.83 pl. 16; fig. 2, 5, 15 [lower and middle
Eocene, Kilwa Masoko, Tanzania]; [Not Cushman and
Jarvis, 1929]
1968 Hantkenina mexicana Cushman. - Raju : p.290 pl. 1; fig. 1 [middle Eocene Globigerina frontasa zone,
Karaikal, Cauvery Basin, India]
1968 Hantkenina aragonensis Nuttall. - Raju : p.290 pl. 1; fig. 2, 8 [Globigerina frontosa
Zone, Karaikal, Cauvery Basin, India]
1970 Hantkenina mexicana Cushman. - Samanta : p.207 pl. 3; fig. 11-12 [middle Eocene Orbulinoides beckmanni
Zone, Lakhpat, Cutch, India]
1975 Hantkenina aragonensis Nuttall. - Stainforth et al. : p.169 pl. 36; fig. 3-4 [Hantkenina aragonensis Zone, Turkmenia, USSR]
p 1979 Hantkenina (Avagonella) mexicana sensu lato Cushman. - Blow : p.1165 pl. 167, fig. 1-5;
pl. 239, fig. 1-6 [middle Eocene Zone
P1 1, Kilwa area, Tanzania, Sample RS.241
1981 Hantkenina nuttalli Toumarkine. - Toumarkine : p.112 pl. 1; fig. 4 [upper
Lower Eocene, Aragon Fm., La Antigua, Mexico]
1985 Hantkenina nuttalli Toumarkine. - Toumarkine & Luterbacher : p.121 pl. 23; fig. 3-5 [lower middle Eocene Hantkenina nuttalli Zone, Rio
Sambre Section, Font Hill Fm., Jamaica]
2003 Hantkenina nuttalli Toumarkine. - Coxall et al. : p.245 pl. 5; fig. 1, 5 [lower middle Eocene
Zone P10, ODP Hole 865B, equatorial Pacific Ocean]
2006 Hantkenina mexicana Cushman. - Pearson et al. : p.244 pl. 8.10; fig. 1-21 (Pl. 8.10, Fig. 1 : original illustration of the holotype
of Hantkenina mexicana Cushman)
(Pl. 8.10, Figs. 2-3: new SEMs of the holotype of
Hantkenina nuttalli Toumarkine; this specimen is also a syntype of H. mexicana var. aragonensis
Nuttall)
|
| References: |
Cushman,J.A. (1924):
A new genus of Eocene foraminifera . Proceedings of the U.S. National Museum Vol. 66 p. 1-4
Nuttall,W.L.F. (1930):
Eocene foraminifera from Mexico . Journal of Paleontology Vol. 4 p. 271-293
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
Thalmann,H.E. (1942):
Foraminiferal genus Hantkenina and its subgenera . American Journal of Sciences Vol. 240 p. 809-823
Brönnimann,P. (1950):
The Genus Hantkenina Cushman in Trinidad and Barbados, B.W.I. . Journal of Paleontology Vol. 24 p. 397-420
Subbotina,N.N. (1953):
Fossil foraminifera of the USSR. Globigerinidae, Hantkeninidae and Globorotaliidae [in Russian] . Trudy Vsesoyuznogo Neftyanogo Nauchno-Isledovatelskogo Geologo-Razvedochnogo Instituta (VNIGRI), Novaya Seriya Vol. 76 p. 1-296
Bolli,H.M.; Loeblich,A.R. and Tappan,H. (1957):
The Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae, and Globotruncanidae . U.S. National Museum Bull. Vol. 215 p. 3-50
Ramsay,W.R. (1962):
Hantkenininae in the Tertiary rocks of Tanganyika . Contributions from the Cushman Foundation for Foraminiferal Research Vol. 13 p. 79-89
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
Samanta,B.K. (1970):
Middle Eocene Planktonic Foraminifera from Lakhpat, Cutch, Western India . Micropaleontology Vol. 16
Stainforth,R.M.; Lamb,J.L.; Luterbacher,H.P.; Beard,J.H. and Jeffords,R.M. (1975):
Cenozoic planktonic foraminiferal zonation and characteristics of index forms . Paleontological ContributionsArticle 62 p. 425
Blow,W.H. (1979):
The Cainozoic Globigerinida. 3 Vols p. 1413 pp
Toumarkine,M. (1981):
Discussion de la validité de l'espèce Hantkenina aragonensis Nuttall, 1930. Description de Hantkenina nuttalli n.sp. . Cahiers de Micropaleontologie Vol. 4 p. 109-19
Toumarkine,M. and Luterbacher,H.P. (1985):
Paleocene and Eocene Planktic Foraminifera.
In: Plankton Stratigraphy p. 87-154
Coxall,H.K..; Huber,B.T. and Pearson,P.N. (2003):
Origin and morphology of the Eocene planktonic foraminifer Hantkenina . Journal of Foraminiferal Research Vol. 33 p. 237-261
Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006):
Atlas of Eocene Planktonic Foraminifera. p. 1-513
|
This work is licensed under a Creative Commons Attribution 2.5 License.
|
|
Taxon Concept provided by