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Species Hantkenina dumblei Weinzierl & Applin 1929 | ||||||
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| Diagnosis / Definition: | ||||||
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Pearson et al. (2006): DESCRIPTION. Type of wall: Smooth, normal perforate and probably nonspinose; tubulospine surface smooth or with fine spiral striations, imperforate or perforated by small sparsely distributed pores. Test morphology: Planispiral, involute, biumbilicate and laterally compressed; 5-7 chambers in the final whorl, expanding and lengthening rapidly as added; chambers subtriangular, closely appressed and in contact with each other along their entire radial length; each chamber of the final whorl extends into a hollow tubulospine; aperture is an elongated equatorial arch, extending about halfway up the apertural face, widening towards the base into weak basal lobes, bordered by an imperforate flaring lip; sutures depressed, straight, becoming sigmoidal with small 'web-like' remnants of relict apertures sometimes present within them; tubulospines short and stout on early chambers, becoming long and slender in later stages, sometimes extremely long, arising sharply from the supporting chamber wall, inclined forward slightly in the direction of coiling (-457, positioned close to or at the anterior chamber suture; anterior chamber shoulder is nonexistent giving weak incisions between chambers, distal ends taper into fine points, unornamented or with very small finger-like projections (coronet structure of Ramsay, 1962), a small terminal aperture opening from the axial canal can sometimes be observed in the adult chanlbers of well preserved specimens. Size: Maximum diameter (excluding tubulospines) 0.40-90 mm. |
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| Discussion / Comments: | ||||||
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Toumarkine & Luterbacher (1985): Hantkenina dumblei has a more compact and more compressed test than H. nuttalli and H. mexicana. The chambers encroach 5 on each other and tend to fuse. The periphery is less lobate than in H. liebusi but more so than in H. alabamensis. Pearson et al. (2006): DISTINGUISHING FEATURES.- Hantkenina dumblei is distinguished from H. liebusi by the larger size, more continuous peripheral outline, greater number of chambers in the adult whorl and by the anterior, near sutural position of the tubulospines. It is differentiated from H. lehneri by the more continuous periphery and broad-based, triangular shape of the final whorl chambers. It is distinguished from H. compressa and H. alabamensis by two principal features. Firstly, the peripheral outline is more rapidly expanding along the radial axis, and second, chambers are usually free of contact with the tubulospine of the previous chamber, whereas in the latter species the tubulospines contact and overlap with the posterior wall of the adjacent younger chamber. In addition, tubulospines in H. dumblei are inclined at a relatively low angle, whereas in H. alabamensis they are strongly inclined with respect to the test periphery. It differs from H. australis in the larger size and having straight tubulospines. DISCUSSION.- Blow (1979), like Brönnimann (1 950), recognized an evolutionary relationship between H. dumblei and the lower middle Eocene hantkeninids, e.g., H. mexicana, but considered it to be unrelated to later species, e.g., H. alabamensis. According to Blow, the early middle and late middle Eocene groups evolved independently from separate Pseudohastigerina ancestors. Morphometric analysis (Coxall, 2000) and stratigraphic evidence from deep-sea cores demonstrate that the H. alabamensis morphology evolved gradually from H. dumblei via the intermediate H. compressa and, thus, as argued by Pearson and others (1993), the hantkeninids are a monophyletic group. In contrast to Blow (1979) therefore, we regard H. dumblei as an intermediate morphospecies within a single continuous evolving lineage, not as the end member of an early hantkeninid radiation. PHYLOGENETIC RELATIONSHIPS.- Hantkenina dumblei evolved from H. liebusi by an increase in the rate of chamber expansion, closer appression of the chambers and forward migration of the tubulospines. It is closely related to H. compressa, which is intermediate between this form and H. alabamensis. STRATIGRAPHIC RANGE.- Middle Eocene, mid Zone E9 to mid E13. GEOGRAPHIC DISTRIBUTION.- This species has a global distribution in mid-low latitudes. It occurs in abundance at ODP Site 865 in Zones E10-E11 in association with Hantkenina lehneri and Morozovelloides lehneri. It has also been found at relatively high northerly latitudes compared to other hantkeninid species, e.g. ODP Site 647 (North Atlantic) in association with H. australis. STABLE ISOTOPE PALEOBIOL0GY.- Hantkenina dumblei has higher ō18O and lower ō13C than Morozovelloides and a similar isotopic signature to Turborotalia frontosa (Pearson and others, 1993,2001; Coxall and others, 2000), suggesting a deep to intermediate depth habitat. This is supported by the boron isotope data of Pearson and Palmer (1 999). There is no ō13C enrichment trend with increasing test size. |
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| Systematics: | ||||||
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15 Classis Foraminifera Genus Hantkenina Species Hantkenina alabamensis 35 Ordo Foraminiferida Superfamilia Globigerinaceae Familia Hantkeninidae Genus Hantkenina Species Hantkenina dumblei |
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| Synonym list: | ||||||
| Toumarkine & Luterbacher (1985): 1929 Hantkenina dumblei Weinzierl & Applin. - Weinzierl & Applin : p.402 pl 43 figs 5a-b (type reference)
1950 Hantkenina dumblei Weinzierl & Applin. - Brönnimann : p.409 (lectotype= specimen figured by Weinzierl & Applin, 1929, pl 43 fig. 5b))
1985 Hantkenina dumblei Weinzierl & Applin. - Toumarkine & Luterbacher : p.123 figs 24,1-5
Pearson et al. (2006): 1929 Hantkenina dumblei Weinzierl & Applin. - Weinzierl & Applin : p.402 pl. 43; fig. 5a-b, lectotype = fig. 5b (designated by Brönnimann, 1950) [middle Eocene, Subsurface Yegua Fm. of the Texas
Gulf Coast]
1939 Hantkenina cf. dumblei Weinzierl & Applin. - Cushman & Siegfus : p.32 pl. 7; fig. 2 [middle Eocene,
Kreyenhagen shale, California]
1942 Hantkenina (Applinella) dumblei Weinzierl & Applin. - Thalmann : p.814 pl. 1; fig. 2a-b (reillustrated Weinzierl and Applin's specimens)
1950 Hantkenina (Applinella) dumblei Weinzierl & Applin. - Brönnimann : p.408 pl. 55; fig. 18, 22-23 [lower and middle
Eocene, Navet Fm., Trinidad]
1968 Hantkenina dumblei Weinzierl & Applin. - Raju : p.290 pl. 1; fig. 5 [middle Eocene
Truncorotaloides topilensis Zone, Karaikal, India].
1979 Hantkenina (Aragonella) dumblei Weinzierl & Applin. - Blow : p.1169 pl. 182; fig. 5-10 [middle Eocene Zone
P l l, DSDP Sample 2 1A-1-4, 148- 150 cm, South Atlantic
Ocean]
1992 Hantkenina dumblei Weinzierl & Applin. - Rajshekar : p.500 pl. 1; fig. 4 [middle Eocene,
Andaman Island, Indian Ocean]
2006 Hantkenina dumblei Weinzierl & Applin. - Pearson et al. : p.239 pl. 8.7; fig. 1-19 (Pl. 8.7, Figs. 1-2: new SEMs of the lectotype of
Hantkenina dumblei Weinzerl and Applin)
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| Was used in synonym list of: | ||||||
| Specimen: | ||||||
| Cushman Collection - Smithsonian Museum of Natural History, Washington, D.C., Inventory number: USNM 12204 |
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| References: | ||||||
Weinzierl,L.L. and Applin,E.R. (1929): Cushman,J.A. and Siegfus,S.S.. (1939): Thalmann,H.E. (1942): Brönnimann,P. (1950): Raju,D.S.N. (1968): Blow,W.H. (1979): Toumarkine,M. and Luterbacher,H.P. (1985): Rajshekar,C.. (1992): Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006): |
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| Anonymous: Unedited TaxonConcept data | ||||||
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