Hantkenina mexicana Cushman 1924 (TaxonConcept

Anonymous: Unedited TaxonConcept data

Notice: This catalogue page may contain unedited data.

Species Hantkenina mexicana Cushman 1924

Alternative name:

Hantkenina (Aragonella) mexicana Cushman 1924

Hantkenina (Avagonella) mexicana Cushman 1924

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]

1939 Hantkenina mexicana var. aragonensis Nuttall. - Rey : p.323 pl. 22; fig. 3 [Lutétien supérior, Nummulitique de Rharb, Morocco]

1942 Hantkenina (Aragonella) aragonensis Nuttall. - Thalmann : p.811 pl. 1; fig. 1 (= pl. 24, fig. 1 of Nuttall, 1930)

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]

1953 Hantkenina aragonensis Nuttall. - Subbotina : p.143 pl. 1; fig. 13 (refigured holotype)

1957 Hantkenina aragonensis Nuttall. - Bolli et al. : pl. 2; fig. 3a-b ( = pl. 24, fig. 3 of Nuttall (1930))

1962 Hantkenina (Avagonella) mexicana Cushman. - Ramsay : p.81 pl. 16; fig. 1-2, 5, 15 [lower and middle Eocene, Kilwa Masoko, Tanzania]

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

1979 Hantkenina (Aragonella) mexicana mexicana Cushman. - Blow : p.1166 pl. 167; fig. 1-5 [middle Eocene, Zone P1 1 , Kilwa area, Tanzania]

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

Anonymous: Unedited TaxonConcept data

This work is licensed under a Creative Commons Attribution 2.5 License.

Back to Search

Taxon relations
pdf
Ranking (experimental)

Taxon Concept provided by
Home \| Search