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


Diagnosis / Definition:
Pearson et al. (2006):
DESCRIPTION. Type of wall: The wall is layered and perforate, with a smooth or weakly cancellate surface. Test morphology: Planispiral or pseudoplanispiral, laterally compressed, 4-5 rapidly expanding chambers in the final whorl; final chamber, and up to three of the preceding chambers, radially elongate, at least one of these ending in either a terminal nub or cylindrical projection ('proto-tubulospine'); prototubulospines are smooth and distinctly porous (although pore density may be reduced at the distal ends) in contrast to the true tubulospines of H. mexicana and subsequent species, which are usually imperforate; distal chamber ends can be inclined in an anterior, posterior or dorso-ventral direction and pseudo-tubulospines are commonly bent; aperture is a high equatorial arch with a smooth, broad lip; lips of relict apertures are commonly observed along the sutures of the final whorl; sutures are shallow and usually curved in a posterior direction. Size: Maximum diameter of holotype (excluding proto-tubulospines) 0.63 mm.
Discussion / Comments:
Pearson et al. (2006):
ETYMOLOGY.- Named in honor of Dr. Joyce M. Singano, chief micropaleontologist at the Tanzania Petroleum Development Corporation. DISTINGUISHING FEATURES.- Hantkenina singanoae differs from Clavigerinella caucasica by possessing rudimentary terminal constrictions andlor cylindrical extensions to the chamber ends. It differs from H. mexicana in lacking true non-porous tubulospines. DISCUSSION.- The species is erected to include a range of diverse morphologies that appear transitional between Clavigerinella caucasica and H. mexicana. The Clavigerinella caucasica-Hantkenina singanoae interface is not clear-cut because the transition between the two is gradual. However, we favor placing singanoae in Hantkenina rather than Clavigerinella because it possesses proto-tubulospines andlor terminal nubs, structures that are considered homologous to tubulospines. No such structures are present in Clavigerinella. PHYLOGENETIC RELATIONSHIPS.- Hantkenina singanoae evolved from C. caucasica by constriction of the terminal chamber ends. This transitional form evolved into Hantkenina mexicana by further elongation of the protuberance and reduction in pore density to form elongated, nonporous tubulospines of Hantkenina proper. STRATIGRAPHIC RANGE.- Restricted to uppermost lower Eocene Zone E7 and basal E8, overlapping slightly with Hantkenina mexicana. GEOGRAPHIC DISTRIBUTION.- So far only found in Tanzania and Austria. STABLE ISOTOPE PALEOBIOL0GY.- No data available.
Systematics:

35
 Ordo Foraminiferida
  Superfamilia Globigerinaceae
   Familia Hantkeninidae
    Genus Hantkenina
     Species Hantkenina singanoae
Synonym list:
Pearson et al. (2006):
2003 "Clavigerinella" Hantkenina transition Coxall et al.. - Coxall et al. : p.250 pl. 6; fig. 3, 16 [lower middle Eocene, Helvetikum Section, Buntmergelserie, Austria, Gohrbandt (1967) sample 6411-36/4b].
2004 Hantkenina sp. . - Pearson et al. : p.37 pl. 2; fig. 18-21 (transitional Hantkenina sp. Pearson and others, 2004); [Zone E7, TDP Site 2, Tanzania].
2006 Hantkenina n sp. singanoae Pearson & Coxall. - Pearson et al. : p.251 pl. 8.13; fig. 1-17 (Pl. 8.13, Figs. 1-4: SEMs of holotype)
References:

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.; Nicholas,C.J..; Singano,J.M..; Bown,P.R..; Coxali,H.K..; van Dongen,B.E..; Huber,B.T.; Karega,A..; Lees,J.A..; Misaky,E..; Pancost,R.D..; Pearson,M.. and Roberts,A.P.. (2004):
Paleogene and Cretaceous sediment cores from the Kilwa and Lindi areas of coastal Tanzania: Tanzania Drilling Project Sites 1-5 . Journal of African Earth Sciences Vol. 39 p. 25-62

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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