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Species Globigerinatheka korotkovi Keller 1946


Diagnosis / Definition:
Pearson et al. (2006):
DESCRIPTION. Type of wall: Spinose, cancellate, moderately encrusted with pores about 0.04 mm in diameter. Test morphology: Test shape sac-like consisting of 2-3 whorls arranged in a high trochospire; chambers subglobular with three chambers in the last whorl; sutures distinct, depressed, straight to slightly curved; peripheral outline rather compact; primary aperture a medium-sized subcircular arch at the junction of the sutures of the last three chambers with one subcircular secondary aperture almost identical to the primary one; other much smaller secondary apertures may be present on the spiral side of the previous chambers. Size: Dimensions of the holotype: diameter 0.35 mm; thickness 0.58 mm.
Discussion / Comments:
Pearson et al. (2006):
DISTINGUISHING FEATURES.- This morphotype is characterized by a high trochospire with three chambers in the last whorl, a rather compact peripheral outline and subcircular primary and supplementary apertures. Based on the presence of at least one supplementary aperture, the species korotkovi is included here in the genus Globigerinatheka. Globigerinatheka korotkovi differs from Subbotina's species rubriformis in having a much shorter (not turreted) spire and at least one subcircular supplementary aperture; it differs from G. subconglobata in having a last chamber that is much larger, and subcircular openings much smaller than G. index. DISCUSSION.- Keller (1946), in the original discussion, stated that "the present species differs from the Paleogene Globigerinoides conglobatus Brady from the upper Eocene of the Sotchi region in its much smaller dimensions (0.35-0.37 mm for the Cretaceous form and 0.5-0.6 mm for the Paleogene) and in the single type of structure shown by the representatives of this species". Keller (1946) also emphasized that his species korotkovi is represented only as "regulZrly constructed forms" contrary to the high morphological variations observed in what he called the Paleogene Globigerinoides conglobatus. Subbotina (1 953) reillustrated Keller's specimen and provided the original description, and Bolli (1972) refigured Subbotina's drawings. Both authors, however, did not mention whether they had found G. korotkovi, nor did they discuss the validity of Keller's species. On the other hand, Bolli (1972) regarded G. korotkovi as a subspecies of G. index. Following Subbotina (1953), and partially Bolli (1972), later authors ignored korotkovi and attributed common, high-spired globigerinathekid specimens to the species Globigerinoides rubriformis erected by Subbotina in 1953. However, the illustrations of rubrijbrmis, including the holotype (see Subbotina, 1953, pl. 14: figs. 6-9) do not show supplementary apertures. The exception is the specimen figured on Subbotina's pl. 13, 19a-b, which is here included in G. tropicalis, but the species needs further study to determine its taxonomic validity. DISCUSSION.- Keller (1946), in the original discussion, stated that "the present species differs from the Paleogene Globigerinoides conglobatus Brady from the upper Eocene of the Sotchi region in its much smaller dimensions (0.35-0.37 mm for the Cretaceous form and 0.5-0.6 mm for the Paleogene) and in the single type of structure shown by the representatives of this species". Keller (1946) also emphasized that his species korotkovi is represented only as "regulZrly constructed forms" contrary to the high morphological variations observed in what he called the Paleogene Globigerinoides conglobatus. Subbotina (1 953) reillustrated Keller's specimen and provided the original description, and Bolli (1972) refigured Subbotina's drawings. Both authors, however, did not mention whether they had found G. korotkovi, nor did they discuss the validity of Keller's species. On the other hand, Bolli (1972) regarded G. korotkovi as a subspecies of G. index. Following Subbotina (1953), and partially Bolli (1972), later authors ignored korotkovi and attributed common, high-spired globigerinathekid specimens to the species Globigerinoides rubriformis erected by Subbotina in 1953. However, the illustrations of rubrijbrmis, including the holotype (see Subbotina, 1953, pl. 14: figs. 6-9) do not show supplementary apertures. The exception is the specimen figured on Subbotina's pl. 13, 19a-b, which is here included in G. tropicalis, but the species needs further study to determine its taxonomic validity. The middle to early late Eocene globigerinathekid population contains common morphotypes that exhibit a sac-like test with a medium long spire and one subcircular supplementary aperture almost identical to the primary one. So, despite Keller's poor description, we think that these sac-like, high-spired morphologies are best represented by Keller's species korotkovi. Keller's species shows some similarities in general shape with the paratype of G. index illustrated by Finlay in his fig. 87, but redrawing of the latter by Hornibrook (1958) shows well incised sutures lacking in G. korotkovi. Blow (1979) considered G. korotkovi as taxonomically indistinguishable from G. semiinvoluta (= Porticulasphaera semiinvoluta, Blow, 1979, p. 788), an attribution here rejected. In addition, Blow (1979) considered most of Subbotina's specimens of G. rubriformis, including the holotype, as immature specimens of Porticulapshaera semiinvoluta (p. 8 13), which we also reject here. The specimen in Blow, 1979, pl. 18 1, fig. 3 annotated as a typical G. kugleri, as well as the specimen in Blow, 1979, pl. 174, fig. 3 considered as atypical G. index, seem close to G. korotkovi for their prominent high spire and high subcircular primary aperture, respectively. PHYLOGENETIC RELATIONSHIPS.- Bolli (1972) suggested that G. rubriformis (here G. korotkovi) may be regarded as a high-spired variant of G. index and G. tropicalis, a hypothesis not accepted here as we consider G. korotkovi to be a valid taxon which probably descended from G. subconglobata. G EOGRAPHIC DISTRIBUTION.- Described from the Caucasus, it is commonly found in low and middle latitudes from deep-sea and land sections. STABLE ISOTOPE PALEOBIOL0GY.- No data available.
Systematics:

35
 Ordo Foraminiferida
  Superfamilia Globigerinaceae
   Familia Globigerinidae
    Genus Globigerinatheka
     Species Globigerinatheka korotkovi
Synonym list:
Pearson et al. (2006):
1946 Globigerinatheka korotkovi Keller. - Keller : p.89 pl. 2; fig. 14-16 [Upper Cretaceous, base Senonian, Gueniokh horizon, River Khosta, near Sotchi, western Caucasus] (fide Ellis and Messina)
1953 Globigerinatheka korotkovi Keller. - Subbotina : p.90 pl. 14; fig. 1a, b (redrawn holotype)
1968 Globigerapsis rubriformis Subbotina. - Samuel & Salaj : text-fig. 38 [upper Eocene ?Globigerina officinalis Zone, Magura Flysch, Slovakia]; [Not Subbotina, 1953]
1969 Globigerapsis index Finlay. - Blow : pl. 27; fig. 1-2 [middle Eocene Zone P13, Kilwa area, Tanzania]; [Not Finlay, 1945]
1970 Globigerinoides rubriformis Subbotina. - Samanta : pl. 2; fig. 9-10 [middle Eocene Orbulinoides beckmanni Zone, Lakhpat, Cutch, India]; [Not Subbotina, 1953]
1970 Globigerapsis sp. . - Samanta : p.200 pl. 2; fig .19 [middle Eocene Orbulinoides beckmanni Zone, Lakhpat, Cutch, India]
1972 Globigerinatheka index rubriformis Subbotina. - Bolli : pl. 1; fig. 5, 11-12 [middle Eocene Globigerinatheka subconglobata subconglobata Zone, Possagno Section, northern Italy]
1975 Globigerinatheka index rubriformis Subbotina. - Toumarkine : pl. 4; fig. 8 [middle Eocene Globorotalia lehneri Zone, DSDP Site 313, Mid Pacific Mountains]
1975 Globigerinatheka index Finlay. - Stainforth et al. : fig. 56.8a, b (from Blow, 1969: pl. 27: figs. 1-2)
1975 Globigerinatheka subconglobata subconglobata Shutskaya. - Toumarkine : pl. 4, fig. 2 [middle Eocene Globorotalia lehneri Zone, DSDP Site 3 13, Mid Pacific Mountains]; [Not Shutskaya, 1958]
1978 Globigerinatheka index rubriformis Subbotina. - Toumarkine : pl. 4; fig. 17-20 [middle Eocene G. subconglobata subconglobata to Morozovella lehneri Zone, DSDP Site 363, South Atlantic Ocean]
1978 Globigerinatheka index tropicalis Blow & Banner. - Toumarkine : pl. 4; fig. 16 [upper Eocene Globigerinatheka semiinvoluta Zone, DSDP Site 363, South Atlantic Ocean]; [Not Blow and Banner, 1962]
1979 Globigerapsis kugleri Bolli et al.. - Blow : pl. 181; fig. 3 [middle Eocene Zone P11, DSDP Hole 21A, South Atlantic Ocean]. [Not Bolli, Loeblich and Tappan, 1957]
1983 Globigerinatheka index rubriformis Subbotina. - Toumarkine : pl. 19; fig. 18-19 [middle Eocenc G. subconglobata subconglobata to G. lehneri Zone, DSDP Site 363, South Atlantic Ocean]. [Not Subbotina, 1953]
1991 Globigerinatheka rubriformis Subbotina. - Nocchi et al. : pl. 4; fig. 30 [upper Eocene Zone P15, ODP Hole 702A, South Atlantic Ocean]; [Not Subbotina, 1953]
1992 Globigerinatheka index Finlay. - Berggren : pl. 3; ?fig. 8 [middle Eocene, ODP Hole 748B, Kerguelen Plateau, Indian Ocean]. [Not Finlay, 1945]
2006 Globigerinatheka korotkovi Keller. - Pearson et al. : p.188 pl. 7.6; fig. 1-16 (Pl. 7.6, Figs. 1, 2: reillustration of holotype of Globigerinoides korotkovi Keller)
2006 Globigerinatheka index korotkovi Keller. - Pearson et al. : p.126 text-fig. 61-62 (redrawn holotype)
Specimen:
Collection 2831 - State Institute of Sciences, Moscow, Inventory number: 98
References:

Keller,B.M. (1946):
Foraminifera from the upper Cretaceous deposits of the sotchi region . Byull. Mosk. Obstch. Ispyt. Prir. n.s., 51 (Sect. Geol.) Vol. 23 p. 83-108

Subbotina,N.N. (1953):
Iskopaemye foraminifery SSSR (Globigerinidy, Khantkenininidy i Globorotaliidy) . Trudy Vsesoyznogo Nauchno-Issledovatel'skogo Geologo-razvedochnogo Instituta (VNIGRI) Vol. 76 p. 296

Samuel,O.. and Salaj,J. (1968):
Microbiostratigraphy and Foraminifera of the Slovak Carpathian Paleogene . Geologicky Ustav Dionyza Stura, Bratislava p. 232

Blow,W.H. (1969):
Late middle Eocene to Recent planktonic foraminiferal biostratigraphy.
In: Proceedings of the First International Conference on Planktonic Microfossils, Geneva 1967 Vol. 1 Eds: Bronnimann, P.Renz, H.H. p. 199-422

Samanta,B.K. (1970):
Middle Eocene Planktonic Foraminifera from Lakhpat, Cutch, Western India . Micropaleontology Vol. 16

Bolli,H.M. (1972):
The Genus Globigerinatheka Brönnimann . Journal of Foraminiferal Research Vol. 2 p. 109-136

Toumarkine,M. (1975):
Middle and Late Eocene planktonic foraminifera from the northwestern Pacific, Leg 32 of the Deep Sea Drilling Project.
In: Initial Reports of the Deep Sea Drilling Project Vol. 32 Eds: Larson, R.L.Moberly, R. p. 735-751

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

Toumarkine,M. (1978):
Planktonic Foraminiferal Biostratigraphy of the Paleogene of Sites 360 to 364 and the Neogene of Sites 362A, 363, and 364 Leg 40.
In: Initial Results of the Deep Sea Drilling Project Vol. 40

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

Toumarkine,M. (1983):
Les Foraminiferes planctoniques de l'Eocéne moyen et supérieur des regions tropicales à temperées chaudes.
In: Thése de Doctorat d'Etat ès Sciences Vol. 6(83-05) p. 219

Nocchi,M.; Amici,E. and Premoli Silva,I. (1991):
Planktonic Foraminiferal Biostratigraphy and Paleoenvironmental Interpretation of Paleocene Faunas from the Subantartic Transect, Leg 114.
In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 114 Eds: Ciesielski, P.F.Kristoffersen, Y.Al, E. p. 233-279

Berggren,W.A. (1992):
Paleogene Planktonic Foraminifera Magnetobiostratigraphy of the Southern Kerguelen Plateau (Sites 747-749).
In: Proceedings of the Ocean Drilling Program, Scientific Results Vol. 120

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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